Gels | April 2023 - Browse Articles

15 pages, 5329 KiB

Open AccessArticle

Facile Enhancement of Electrochemical Performance of Solid-State Supercapacitor via Atmospheric Plasma Treatment on PVA-Based Gel-Polymer Electrolyte

by Dong-Hyun Kim, Suk Jekal, Chan-Gyo Kim, Yeon-Ryong Chu, Jungchul Noh, Min Sang Kim, Neunghi Lee, Woo-Jin Song and Chang-Min Yoon

Gels 2023, 9(4), 351; https://doi.org/10.3390/gels9040351 - 21 Apr 2023

Cited by 8 | Viewed by 3307

Abstract

A facile oxygen (O₂) atmospheric plasma treatment is applied to a polyvinyl alcohol (PVA) matrix to enhance its wettability and hydrophilicity. The optimal plasma treatment conditions are determined by varying the applied plasma power and plasma treatment time. A PVA matrix [...] Read more.

A facile oxygen (O₂) atmospheric plasma treatment is applied to a polyvinyl alcohol (PVA) matrix to enhance its wettability and hydrophilicity. The optimal plasma treatment conditions are determined by varying the applied plasma power and plasma treatment time. A PVA matrix treated with a plasma power of 120 W for 5 s shows the most hydrophilicity owing to successful formation of carbonyl (–CO, >C=O) functional groups without any structural degradation. The plasma-treated PVA matrix is used as the gel-polymer electrolyte of a solid-state supercapacitor (SSC) by immersing solid matrix into various liquid electrolytes, such as sodium sulfate (Na₂SO₄), sulfuric acid (H₂SO₄), and potassium hydroxide (KOH). Compared with the pristine PVA-based device, PVA-120W5/Na₂SO₄-, PVA-120W5/H₂SO₄-, and PVA-120W5/KOH-based SSCs show 2.03, 2.05, and 2.14 times higher specific capacitances, respectively. The plasma-treated PVA matrix shows increased specific capacitance owing to the increased wettability, which in turn increases the ion transportation and reduces the electrical resistance. This study successfully demonstrates that the electrochemical performance of a SSC can be readily enhanced through plasma treatment for a short time (≤5 s). Full article

(This article belongs to the Special Issue Advances in Gel-Based Devices and Flexible Electronics)

► Show Figures

Graphical abstract

12 pages, 4302 KiB

Open AccessArticle

Controlled Lactonization of o-Coumaric Esters Mediated by Supramolecular Gels

by Fabia Cenciarelli, Giuseppe Falini, Demetra Giuri and Claudia Tomasini

Gels 2023, 9(4), 350; https://doi.org/10.3390/gels9040350 - 21 Apr 2023

Cited by 4 | Viewed by 1794

Abstract

Fragrances are volatile organic compounds widely used in our daily life. Unfortunately, the high volatility required to reach human receptors reduces their persistency in the air. To contrast this effect, several strategies may be used. Among them, we present here the combination of [...] Read more.

Fragrances are volatile organic compounds widely used in our daily life. Unfortunately, the high volatility required to reach human receptors reduces their persistency in the air. To contrast this effect, several strategies may be used. Among them, we present here the combination of two techniques: the microencapsulation in supramolecular gels and the use of profragrances. We report a study on the controlled lactonization of four esters derived from o-coumaric acid. The ester lactonization spontaneously occurs after exposure to solar light, releasing coumarin and the corresponding alcohol. To determine the rate of fragrance release, we compared the reaction in solution and in a supramolecular gel and we demonstrated that the lactonization reaction always occurs slower in the gel. We also studied the more suitable gel for this aim, by comparing the properties of two supramolecular gels obtained with the gelator Boc-L-DOPA(Bn)₂-OH in a 1:1 ethanol/water mixture in different gelator concentration (0.2% and 1% w/v). The gel prepared with 1% w/v gelator concentration is stronger and less transparent than the other and was used for the profragrances encapsulation. In any case, we obtained a significative reduction of lactonization reaction in gel, compared with the same reaction in solution. Full article

(This article belongs to the Special Issue Recent Advances in Organogels and Their Applications)

► Show Figures

Graphical abstract

12 pages, 1791 KiB

Open AccessArticle

Bigels as Delivery Systems of Bioactive Fatty Acids Present in Functional Edible Oils: Coconut, Avocado, and Pomegranate

by Manuela Machado, Sérgio Cruz Sousa, Luís Miguel Rodríguez-Alcalá, Manuela Pintado and Ana Maria Gomes

Gels 2023, 9(4), 349; https://doi.org/10.3390/gels9040349 - 21 Apr 2023

Cited by 8 | Viewed by 2170

Abstract

Bioactive fatty acids possess several benefits for human health; however, these molecules show a reduced oxidative stability and consequently reduced bioavailability. This work aimed to develop novel bigels as a strategy to protect bioactive fatty acids present in three different vegetable oils with [...] Read more.

Bioactive fatty acids possess several benefits for human health; however, these molecules show a reduced oxidative stability and consequently reduced bioavailability. This work aimed to develop novel bigels as a strategy to protect bioactive fatty acids present in three different vegetable oils with nutritional attributes (coconut oil, avocado oil, and pomegranate oil) during passage through the gastrointestinal tract (GIT). Bigels were prepared using monoglycerides-vegetable oil oleogel and carboxymethyl cellulose hydrogel. These bigels were analyzed in terms of structure and rheological characteristics. According to the rheological properties, bigels exhibited a solid-like behavior since G’ was higher than G”. The results showed that the proportion of oleogel was essential to the viscosity of the final formulation as an increase in this fraction was responsible for an increase in viscosity. The fatty acids profile was evaluated before and after simulated GIT. The bigels protected the fatty acids against degradation; in the case of coconut oil, the reduction of key fatty acids was 3 times lower; for avocado oil, 2 times lower; and for pomegranate oil, 1.7 times lower. These results suggest that bigels can be used as part of an important strategy for bioactive fatty acid delivery for food applications. Full article

(This article belongs to the Special Issue Recent Progress on Oleogels and Organogels)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Response surfaces for oil-binding capacity (OBC) optimization ((A)-coconut oil, (B)-avocado oil, and (C)-pomegranate oil). Full article ">Figure 2
FTIR spectra of bigel formulation components: (A), coconut oil and corresponding bigel (B), avocado oil and their bigel, and (C), pomegranate oil and corresponding bigel (D). Full article ">Figure 3
Rheological properties of bigels: (A) elastic modulus (G’), (B) viscous modulus (G”), (C) complex viscosity (ƞ*), avocado oil (●), coconut oil (▪), and pomegranate oil (⁺). Full article ">Figure 4
Viscosity curves of bigels vs. shear rate. Full article ">Figure 5
GIT release percentages of the main bioactive fatty acids found in the different vegetable oils: (A) coconut oil, (B) avocado oil, and (C) pomegranate oil. Full article ">Figure 6
Evolution of main bioactive fatty acid release (%) during gastrointestinal digestion. (A) avocado oil and correspondent bigel, (B) coconut oil and coconut oil bigel, and (C) pomegranate oil and correspondent bigel. Full article ">

22 pages, 5851 KiB

Open AccessArticle

Caspofungin-Loaded Formulations for Treating Ocular Infections Caused by Candida spp.

by Noelia Pérez-González, María J. Rodríguez-Lagunas, Ana C. Calpena-Campmany, Nuria Bozal-de Febrer, Lyda Halbaut-Bellowa, Mireia Mallandrich and Beatriz Clares-Naveros

Gels 2023, 9(4), 348; https://doi.org/10.3390/gels9040348 - 20 Apr 2023

Cited by 2 | Viewed by 2065

Abstract

Fungal keratitis causes corneal blindness worldwide. The treatment includes antibiotics, with Natamycin being the most commonly used; however, fungal keratitis is difficult to treat, so alternative therapies are needed. In situ gelling formulations are a promising alternative; this type of formulation has the [...] Read more.

Fungal keratitis causes corneal blindness worldwide. The treatment includes antibiotics, with Natamycin being the most commonly used; however, fungal keratitis is difficult to treat, so alternative therapies are needed. In situ gelling formulations are a promising alternative; this type of formulation has the advantages of eye drops combined with the advantages of ointments. This study was designed to develop and characterize three formulations containing 0.5% CSP: CSP-O1, CSP-O2, and CSP-O3. CSP is an antifungal drug that acts against a diverse variety of fungi, and Poloxamer 407 (P407) is a polymer of synthetic origin that is able to produce biocompatible, biodegradable, highly permeable gels and is known to be thermoreversible. Short-term stability showed that formulations are best stored at 4 °C, and rheological analysis showed that the only formulation able to gel in situ was CSP-O3. In vitro release studies indicated that CSP-O1 releases CSP most rapidly, while in vitro permeation studies showed that CSP-O3 permeated the most. The ocular tolerance study showed that none of the formulations caused eye irritation. However, CSP-O1 decreased the cornea’s transparency. Histological results indicate that the formulations are suitable for use, with the exception of CSP-O3, which induced slight structural changes in the scleral structure. All formulations were shown to have antifungal activity. In view of the results obtained, these formulations could be promising candidates for use in the treatment of fungal keratitis. Full article

(This article belongs to the Special Issue Recent Advances in Gels Engineering for Drug Delivery)

► Show Figures

Graphical abstract

16 pages, 7637 KiB

Open AccessArticle

A Light Scattering Investigation of Enzymatic Gelation in Self-Assembling Peptides

by Stefano Buzzaccaro, Vincenzo Ruzzi, Fabrizio Gelain and Roberto Piazza

Gels 2023, 9(4), 347; https://doi.org/10.3390/gels9040347 - 19 Apr 2023

Cited by 2 | Viewed by 1681

Abstract

Self-assembling peptides (SAPs) have been increasingly studied as hydrogel–former gelators because they can create biocompatible environments. A common strategy to trigger gelation, is to use a pH variation, but most methods result in a change in pH that is too rapid, leading to [...] Read more.

Self-assembling peptides (SAPs) have been increasingly studied as hydrogel–former gelators because they can create biocompatible environments. A common strategy to trigger gelation, is to use a pH variation, but most methods result in a change in pH that is too rapid, leading to gels with hardly reproducible properties. Here, we use the urea–urease reaction to tune gel properties, by a slow and uniform pH increase. We were able to produce very homogeneous and transparent gels at several SAP concentrations, ranging from

c = 1 g / L

to

c = 10 g / L

. In addition, by exploiting such a pH control strategy, and combining photon correlation imaging with dynamic light scattering measurements, we managed to unravel the mechanism by which gelation occurs in solutions of

{(LDLK)}_{3}

-based SAPs. We found that, in diluted and concentrated solutions, gelation follows different pathways. This leads to gels with different microscopic dynamics and capability of trapping nanoparticles. At high concentrations, a strong gel is formed, made of relatively thick and rigid branches that firmly entrap nanoparticles. By contrast, the gel formed in dilute conditions is weaker, characterized by entanglements and crosslinks of very thin and flexible filaments. The gel is still able to entrap nanoparticles, but their motion is not completely arrested. These different gel morphologies can potentially be exploited for controlled multiple drug release. Full article

(This article belongs to the Special Issue Hydrogelated Matrices: Structural, Functional and Applicative Aspects)

► Show Figures

Graphical abstract

12 pages, 3533 KiB

Open AccessArticle

Biomass Chitosan-Based Tubular/Sheet Superhydrophobic Aerogels Enable Efficient Oil/Water Separation

by Wenhui Wang, Jia-Horng Lin, Jiali Guo, Rui Sun, Guangting Han, Fudi Peng, Shan Chi and Ting Dong

Gels 2023, 9(4), 346; https://doi.org/10.3390/gels9040346 - 18 Apr 2023

Cited by 3 | Viewed by 1721

Abstract

Water pollution, which is caused by leakage of oily substances, has been recognized as one of the most serious global environmental pollutions endangering the ecosystem. High-quality porous materials with superwettability, which are typically constructed in the form of aerogels, hold huge potential in [...] Read more.

Water pollution, which is caused by leakage of oily substances, has been recognized as one of the most serious global environmental pollutions endangering the ecosystem. High-quality porous materials with superwettability, which are typically constructed in the form of aerogels, hold huge potential in the field of adsorption and removal of oily substances form water. Herein, we developed a facile strategy to fabricate a novel biomass absorbent with a layered tubular/sheet structure for efficient oil/water separation. The aerogels were fabricated by assembling hollow poplar catkin fiber into chitosan sheets using a directional freeze-drying method. The obtained aerogels were further wrapped with -CH₃-ended siloxane structures using CH₃SiCl₃. This superhydrophobic aerogel (CA ≈ 154 ± 0.4°) could rapidly trap and remove oils from water with a large sorption range of 33.06–73.22 g/g. The aerogel facilitated stable oil recovery (90.07–92.34%) by squeezing after 10 sorption-desorption cycles because of its mechanical robustness (91.76% strain remaining after 50 compress-release cycles). The novel design, low cost, and sustainability of the aerogel provide an efficient and environmentally friendly solution for handling oil spills. Full article

(This article belongs to the Special Issue Gels for Removal and Adsorption)

► Show Figures

Graphical abstract

14 pages, 1598 KiB

Open AccessArticle

Efficient Degradation for Raffinose and Stachyose of a β-D-Fructofuranosidase and Its New Function to Improve Gel Properties of Coagulated Fermented-Soymilk

by Zhou Chen, Yimei Shen and Jiangqi Xu

Gels 2023, 9(4), 345; https://doi.org/10.3390/gels9040345 - 18 Apr 2023

Cited by 4 | Viewed by 1931

Abstract

A novel β-D-fructofuranosidase gene was identified via database mining from Leptothrix cholodnii. The gene was chemically synthesized and expressed in Escherichia coli, resulting in the production of a highly efficient enzyme known as LcFFase1s. The enzyme exhibited optimal activity at pH [...] Read more.

A novel β-D-fructofuranosidase gene was identified via database mining from Leptothrix cholodnii. The gene was chemically synthesized and expressed in Escherichia coli, resulting in the production of a highly efficient enzyme known as LcFFase1s. The enzyme exhibited optimal activity at pH 6.5 and a temperature of 50 °C while maintaining stability at pH 5.5–8.0 and a temperature below 50 °C. Furthermore, LcFFase1s exhibited remarkable resistance to commercial proteases and various metal ions that could interfere with its activity. This study also revealed a new hydrolysis function of LcFFase1s, which could completely hydrolyze 2% raffinose and stachyose within 8 h and 24 h, respectively, effectively reducing the flatulence factor in legumes. This discovery expands the potential applications of LcFFase1s. Additionally, the incorporation of LcFFase1s significantly reduced the particle size of coagulated fermented-soymilk gel, resulting in a smoother texture while maintaining the gel hardness and viscosity formed during fermentation. This represents the first report of β-D-fructofuranosidase enhancing coagulated fermented-soymilk gel properties, highlighting promising possibilities for future applications of LcFFase1s. Overall, the exceptional enzymatic properties and unique functions of LcFFase1s render it a valuable tool for numerous applications. Full article

(This article belongs to the Special Issue Gels Applications on Food Industry)

► Show Figures

Figure 1

Figure 1
Nucleotide and deduced amino acid sequences of the full-length cDNAs and flanking regions of LcFFase1s. Full article ">Figure 2
SDS-PAGE analysis of purified LcFFase1s. Lane M, low molecular weight standard protein markers; lane 1, crude lysate; lane 2, purified LcFFase1s. Full article ">Figure 3
pH and temperature profiles of LcFFase1s. Effect of pH on the activity (a) and stability (b) was performed at 40 °C in 50 mM sodium hydrogen phosphate–citrate buffer. The remaining activities were measured after incubation for 30 min at 40 °C over various pH ranges. Effect of temperature on the activity (c) and thermostability (d) of LcFFase1s was determined at temperatures ranging from 25 °C to 70 °C in 50 mM sodium hydrogen phosphate–citrate buffer (pH 6.5). Full article ">Figure 4
Effect of various metal ions on the β-D-fructofuranosidase of LcFFase1s. Full article ">Figure 5
The ability of β-D-fructofuranosidase LcFFase1s to resist various proteases. Full article ">Figure 6
Hydrolysis of raffinose (a) and stachyose (b) by LcFFase1s. The reaction mixture containing 20 mg/mL of substrates in 50 mM sodium hydrogen phosphate–citrate buffer (pH 6.5) and LcFFase1s (5 U/mL) was incubated at 40 °C. Full article ">Figure 7
Ability of LcFFase1s to catalyze the hydrolysis of soybean (a) and effect of LcFFase1s on the gel properties (b–d) of coagulated fermented-soymilk. Full article ">

11 pages, 1008 KiB

Open AccessArticle

The Impact of Solution Ionic Strength, Hardness, and pH on the Sorption Efficiency of Polychlorinated Biphenyls in Magnetic Nanocomposite Microparticle (MNM) Gels

by Angela M. Gutierrez, Thomas D. Dziubla and J. Zach Hilt

Gels 2023, 9(4), 344; https://doi.org/10.3390/gels9040344 - 18 Apr 2023

Viewed by 1345

Abstract

Environmental conditions of groundwater and surface water greatly vary as a function of location. Factors such as ionic strength, water hardness, and solution pH can change the physical and chemical properties of the nanocomposites used in remediation and the pollutants of interest. In [...] Read more.

Environmental conditions of groundwater and surface water greatly vary as a function of location. Factors such as ionic strength, water hardness, and solution pH can change the physical and chemical properties of the nanocomposites used in remediation and the pollutants of interest. In this work, magnetic nanocomposite microparticle (MNM) gels are used as sorbents for remediation of PCB 126 as model organic contaminant. Three MNM systems are used: curcumin multiacrylate MNMs (CMA MNMs), quercetin multiacrylate MNMs (QMA MNMs), and polyethylene glycol-400-dimethacrylate MNMs (PEG MNMs). The effect of ionic strength, water hardness, and pH were studied on the sorption efficiency of the MNMs for PCB 126 by performing equilibrium binding studies. It is seen that the ionic strength and water hardness have a minimal effect on the MNM gel system sorption of PCB 126. However, a decrease in binding was observed when the pH increased from 6.5 to 8.5, attributed to anion-π interactions between the buffer ions in solution and the PCB molecules as well as with the aromatic rings of the MNM gel systems. Overall, the results indicate that the developed MNM gels can be used as magnetic sorbents for polychlorinated biphenyls in groundwater and surface water remediation, provided that the solution pH is controlled. Full article

► Show Figures

Figure 1

16 pages, 8615 KiB

Open AccessArticle

Effects of Platelet Lysate Gels Derived from Different Blood Sources on Oral Mucosal Wound Healing: An In Vitro Study

by Sook-Luan Ng, Nur Ain Azhar, Siti Balkis Budin, Norliwati Ibrahim, Nur Azurah Abdul Ghani, Norzana Abd Ghafar and Jia-Xian Law

Gels 2023, 9(4), 343; https://doi.org/10.3390/gels9040343 - 17 Apr 2023

Cited by 2 | Viewed by 2214

Abstract

The rapid healing of oral ulcers is important to prevent secondary infection, especially for chronic oral ulcers. Platelet lysate (PL) is rich in growth factors for cell growth and promotes tissue regeneration. Hence, this study was performed to compare the effects of PL [...] Read more.

The rapid healing of oral ulcers is important to prevent secondary infection, especially for chronic oral ulcers. Platelet lysate (PL) is rich in growth factors for cell growth and promotes tissue regeneration. Hence, this study was performed to compare the effects of PL originating from umbilical cord blood (CB) and peripheral blood (PB) on oral mucosal wound healing. The PLs were molded into gel form in the culture insert with the addition of calcium chloride and conditioned medium for sustained release of growth factors. The CB-PL and PB-PL gels were found to degrade slowly in culture and their degradation percentages by weight were 5.28 ± 0.72% and 9.55 ± 1.82% respectively. The results from the scratch assay and Alamar blue assay showed that the CB-PL and PB-PL gels increased the proliferation (148 ± 3% and 149 ± 3%) and wound closure (94.17 ± 1.77% and 92.75 ± 1.80%) of oral mucosal fibroblasts compared to the control with no statistical differences between the two gels, respectively. Quantitative RT-PCR showed that mRNA expressions of collagen-I, collagen-III, fibronectin, and elastin genes in cells treated with CB-PL (11-, 7-, 2-, and 7-fold) and PB-PL (17-, 14-, 3-, and 7-fold) decreased compared with the control, respectively. The concentration of platelet-derived growth factor of PB-PL gel (1303.10 ± 343.96 pg/mL) showed a higher trend than CB-PL gel did (905.48 ± 69.65 pg/mL) from ELISA measurement. In summary, CB-PL gel is as effective as PB-PL gel in supporting oral mucosal wound healing, making it a potential new source of PL for regenerative treatment. Full article

(This article belongs to the Special Issue Gels for Wound Healing)

► Show Figures

Graphical abstract

14 pages, 2684 KiB

Open AccessArticle

Biodegradable Hydrogels Based on Chitosan and Pectin for Cisplatin Delivery

by Regina R. Vildanova, Svetlana F. Petrova, Sergey V. Kolesov and Vitaliy V. Khutoryanskiy

Gels 2023, 9(4), 342; https://doi.org/10.3390/gels9040342 - 17 Apr 2023

Cited by 7 | Viewed by 2447

Abstract

Preparation of stable hydrogels using physically (electrostatically) interacting charge-complementary polyelectrolyte chains seems to be more attractive from a practical point of view than the use of organic crosslinking agents. In this work natural polyelectrolytes—chitosan and pectin—were used, due to their biocompatibility and biodegradability. [...] Read more.

Preparation of stable hydrogels using physically (electrostatically) interacting charge-complementary polyelectrolyte chains seems to be more attractive from a practical point of view than the use of organic crosslinking agents. In this work natural polyelectrolytes—chitosan and pectin—were used, due to their biocompatibility and biodegradability. The biodegradability of hydrogels is confirmed by experiments with hyaluronidase as an enzyme. It has been shown that the use of pectins with different molecular weights makes it possible to prepare hydrogels with different rheological characteristics and swelling kinetics. These polyelectrolyte hydrogels loaded with cytostatic cisplatin as a model drug provide an opportunity for its prolonged release, which is important for therapy. The drug release is regulated to a certain extent by the choice of hydrogel composition. The developed systems can potentially improve the effects of cancer treatment due to the prolonged release of cytostatic cisplatin. Full article

(This article belongs to the Special Issue Physically Cross-Linked Gels and Their Applications)

► Show Figures

Figure 1

15 pages, 3314 KiB

Open AccessArticle

Carbonic Anhydrase Enhanced UV-Crosslinked PEG-DA/PEO Extruded Hydrogel Flexible Filaments and Durable Grids for CO₂ Capture

by Jialong Shen, Sen Zhang, Xiaomeng Fang and Sonja Salmon

Gels 2023, 9(4), 341; https://doi.org/10.3390/gels9040341 - 16 Apr 2023

Cited by 7 | Viewed by 24219

Abstract

In this study, poly (ethylene glycol) diacrylate/poly (ethylene oxide) (PEG-DA/PEO) interpenetrating polymer network hydrogels (IPNH) were extruded into 1D filaments and 2D grids. The suitability of this system for enzyme immobilization and CO₂ capture application was validated. IPNH chemical composition was verified [...] Read more.

In this study, poly (ethylene glycol) diacrylate/poly (ethylene oxide) (PEG-DA/PEO) interpenetrating polymer network hydrogels (IPNH) were extruded into 1D filaments and 2D grids. The suitability of this system for enzyme immobilization and CO₂ capture application was validated. IPNH chemical composition was verified spectroscopically using FTIR. The extruded filament had an average tensile strength of 6.5 MPa and elongation at break of 80%. IPNH filament can be twisted and bent and therefore is suitable for further processing using conventional textile fabrication methods. Initial activity recovery of the entrapped carbonic anhydrase (CA) calculated from esterase activity, showed a decrease with an increase in enzyme dose, while activity retention of high enzyme dose samples was over 87% after 150 days of repeated washing and testing. IPNH 2D grids that were assembled into spiral roll structured packings exhibited increased CO₂ capture efficiency with increasing enzyme dose. Long-term CO₂ capture performance of the CA immobilized IPNH structured packing was tested in a continuous solvent recirculation experiment for 1032 h, where 52% of the initial CO₂ capture performance and 34% of the enzyme contribution were retained. These results demonstrate the feasibility of using rapid UV-crosslinking to form enzyme-immobilized hydrogels by a geometrically-controllable extrusion process that uses analogous linear polymers for both viscosity enhancement and chain entanglement purposes, and achieves high activity retention and performance stability of the immobilized CA. Potential uses for this system extend to 3D printing inks and enzyme immobilization matrices for such diverse applications as biocatalytic reactors and biosensor fabrication. Full article

(This article belongs to the Special Issue Hydrogels, Microgels, and Nanogels: From Fundamentals to Applications)

► Show Figures

Figure 1

Figure 1
Hydrogel filament/grid fabrication system set-up. Full article ">Figure 2
Schematics of the formation of PEG-DA/PEO interpenetrating polymer network hydrogel (IPNH). (Orange stars represent free redicals at the growing chain ends; blue rectangles represent ethylene oxide repeating units). Full article ">Figure 3
FTIR spectra of PEG-DA, PEG-DA after UV-cured, PEO 900K powder, extruded PEG-DA/PEO IPNH, and extruded PEG-DA/PEO IPNH with entrapped NZCA (From top to bottom). Full article ">Figure 4
Properties of extruded PEG-DA/PEO IPNH filament: (a) Effect of curing on a surface or in air on the tensile strength and elongation of filaments extruded at 20 psi, (b) Effect of extrusion pressure on the diameter of filaments cured in air, and (c) Photos demonstrating the flexibility of a filament, which can be bent and twisted (Scale bars = 1 cm). Full article ">Figure 5
Extruded PEG-DA/PEO IPNH grids: (a) No-enzyme control (Scale bar = 1 cm), (b) NZCA-entrapped (Scale bar = 1 cm), (c) Assembled into 2 cm O.D. structured packing, and (d) Assembled packing fitted in a 2 cm I.D. CO2 absorption column. Full article ">Figure 6
Enzyme activity assay on extruded PEG-DA/PEO IPNH grids with different NZCA doses: (a) Samples are cut into circles that fit in the wells of a 24-well plate, (b) Long-term stability of the immobilized NZCA over 150 days in buffer and at room temperature subject to repeated wash and testing, (c) Activity recovery of the immobilized NZCA on Day 0, calculated against the activity of a same amount of dissolved NZCA used in the immobilization, (d) Activity retention on Day 150. Full article ">Figure 7
CO2 gas scrubber test of the assembled PEG-DA/PEO IPNH structured packings: CO2 capture efficiency (a) as a function of NZCA dose and (b) over 1032 h of continuous solvent recirculation. Full article ">

13 pages, 1622 KiB

Open AccessArticle

Bigels as Fat Replacers in Fermented Sausages: Physicochemical, Microbiological, Sensory, and Nutritional Characteristics

by Christina Siachou, Konstantina Zampouni and Eugenios Katsanidis

Gels 2023, 9(4), 340; https://doi.org/10.3390/gels9040340 - 16 Apr 2023

Cited by 11 | Viewed by 2419

Abstract

Olive oil bigels structured with monoglycerides, gelatin, and κ-carrageenan were designed for the partial substitution of pork backfat in fermented sausages. Two different bigels were used: bigel B60 consisted of 60% aqueous and 40% lipid phase; and bigel B80 was formulated with 80% [...] Read more.

Olive oil bigels structured with monoglycerides, gelatin, and κ-carrageenan were designed for the partial substitution of pork backfat in fermented sausages. Two different bigels were used: bigel B60 consisted of 60% aqueous and 40% lipid phase; and bigel B80 was formulated with 80% aqueous and 20% lipid phase. Three different pork sausage treatments were manufactured: control with 18% pork backfat; treatment SB60 with 9% pork backfat and 9% bigel B60; and treatment SB80 with 9% pork backfat and 9% bigel B80. Microbiological and physicochemical analyses were carried out for all three treatments on 0, 1, 3, 6, and 16 days after sausage preparation. Bigel substitution did not affect water activity or the populations of lactic acid bacteria, total viable counts, Micrococcaceae, and Staphylococcacea during the fermentation and ripening period. Treatments SB60 and SB80 presented higher weight loss during fermentation and higher TBARS values only on day 16 of storage. Consumer sensory evaluation did not identify significant differences among the sausage treatments in color, texture, juiciness, flavor, taste, and overall acceptability. The results show that bigels can be utilized for the formulation of healthier meat products with acceptable microbiological, physicochemical, and organoleptic characteristics. Full article

(This article belongs to the Special Issue Functionality of Oleogels and Bigels in Foods: Effective Strategies to Deliver Improved Nutrition and Health (2nd Edition))

► Show Figures

Graphical abstract

15 pages, 2377 KiB

Open AccessArticle

Patient-Specific 3D Printed Soft Models for Liver Surgical Planning and Hands-On Training

by Arnau Valls-Esteve, Aitor Tejo-Otero, Pamela Lustig-Gainza, Irene Buj-Corral, Felip Fenollosa-Artés, Josep Rubio-Palau, Ignasi Barber-Martinez de la Torre, Josep Munuera, Constantino Fondevila and Lucas Krauel

Gels 2023, 9(4), 339; https://doi.org/10.3390/gels9040339 - 16 Apr 2023

Cited by 12 | Viewed by 3413

Abstract

Background: Pre-surgical simulation-based training with three-dimensional (3D) models has been intensively developed in complex surgeries in recent years. This is also the case in liver surgery, although with fewer reported examples. The simulation-based training with 3D models represents an alternative to current [...] Read more.

Background: Pre-surgical simulation-based training with three-dimensional (3D) models has been intensively developed in complex surgeries in recent years. This is also the case in liver surgery, although with fewer reported examples. The simulation-based training with 3D models represents an alternative to current surgical simulation methods based on animal or ex vivo models or virtual reality (VR), showing reported advantages, which makes the development of realistic 3D-printed models an option. This work presents an innovative, low-cost approach for producing patient-specific 3D anatomical models for hands-on simulation and training. Methods: The article reports three paediatric cases presenting complex liver tumours that were transferred to a major paediatric referral centre for treatment: hepatoblastoma, hepatic hamartoma and biliary tract rhabdomyosarcoma. The complete process of the additively manufactured liver tumour simulators is described, and the different steps for the correct development of each case are explained: (1) medical image acquisition; (2) segmentation; (3) 3D printing; (4) quality control/validation; and (5) cost. A digital workflow for liver cancer surgical planning is proposed. Results: Three hepatic surgeries were planned, with 3D simulators built using 3D printing and silicone moulding techniques. The 3D physical models showed highly accurate replications of the actual condition. Additionally, they proved to be more cost-effective in comparison with other models. Conclusions: It is demonstrated that it is possible to manufacture accurate and cost-effective 3D-printed soft surgical planning simulators for treating liver cancer. The 3D models allowed for proper pre-surgical planning and simulation training in the three cases reported, making it a valuable aid for surgeons. Full article

(This article belongs to the Special Issue 3D Printing of Gel-Based Materials)

► Show Figures

Figure 1

Figure 1
Graphical abstract representation of the high-level process followed in cases presented in this research. Full article ">Figure 2
Quantitative analysis of the surgical planning prototype. The real organ 3D model scan was used as the reference point. The surface colour of the phantom model represents the distance error. (A) Case #1. (B) Case #2. (C) Case #3. The distance is measured in mm. (D) Comparison between the prototype of case #2 and the tumour after its removal. Full article ">Figure 3
3D models in CAD file and manufactured final model of the different cases: (A) Case #1. (B) Case #2. (C) Case #3. Full article ">Figure 4
Process flowchart representation of the digital workflow for 3D printing pre-surgical simulation-based training. Full article ">Figure 5
(A) CT image with the different anatomical parts highlighted: (1) Liver is outlined in blue; (2) Portal system is circled in red; (3) Dilated intrahepatic biliary tract (tumour) is outlined in brown; and (4) the rest of the tumour, which originates in the biliary tract, is circled in green. (Left) Coronal or frontal plane. (Right) Axial plane. (B) MRI of the case (Axial plane). The tumour is contoured in red. The liver is contoured in blue. (C) Left: MRI of the case (Frontal plane). Right: MRI of the case (Axial plane). The tumour is contoured in red. The liver is contoured in blue. Full article ">Figure 6
Workflow for the design of the 3D model. (A) Case #1. (B) Case #2. (C) Case #3. Full article ">Figure 7
Surgical planning prototypes. (A) Case #1: Rhabdomyosarcoma (bar corresponds to 3 cm). (B) Case #2: Hepatoblastoma (bar corresponds to 5 cm). (C) Case #3: Mesenchymal Hamartoma (bar corresponds to 3 cm). Full article ">

15 pages, 4263 KiB

Open AccessArticle

Flexible Polymer-Ionic Liquid Films for Supercapacitor Applications

by Christo Novakov, Radostina Kalinova, Svetlana Veleva, Filip Ublekov, Ivaylo Dimitrov and Antonia Stoyanova

Gels 2023, 9(4), 338; https://doi.org/10.3390/gels9040338 - 16 Apr 2023

Cited by 5 | Viewed by 1760

Abstract

Mechanically and thermally stable novel gel polymer electrolytes (GPEs) have been prepared and applied in supercapacitor cells. Quasi-solid and flexible films were prepared by solution casting technique and formulated by immobilization of ionic liquids (ILs) differing in their aggregate state. A crosslinking agent [...] Read more.

Mechanically and thermally stable novel gel polymer electrolytes (GPEs) have been prepared and applied in supercapacitor cells. Quasi-solid and flexible films were prepared by solution casting technique and formulated by immobilization of ionic liquids (ILs) differing in their aggregate state. A crosslinking agent and a radical initiator were added to further stabilize them. The physicochemical characteristics of the obtained crosslinked films show that the realized cross-linked structure contributes to their improved mechanical and thermal stability, as well as an order of magnitude higher conductivity than that of the non-crosslinked ones. The obtained GPEs were electrochemically tested as separator in symmetric and hybrid supercapacitor cells and showed good and stable performance in the investigated systems. The crosslinked film is suitable for use as both separator and electrolyte and is promising for the development of high-temperature solid-state supercapacitors with improved capacitance characteristics. Full article

(This article belongs to the Special Issue Gels for Flexible Electronics and Energy Devices)

► Show Figures

Figure 1

14 pages, 2447 KiB

Open AccessArticle

Fabrication, Characterization, and Antioxidant Potential of Sodium Alginate/Acacia Gum Hydrogel-Based Films Loaded with Cinnamon Essential Oil

by Saurabh Bhatia, Ahmed Al-Harrasi, Yasir Abbas Shah, Halima Waleed Khalifa Altoubi, Sabna Kotta, Priyanka Sharma, Md. Khalid Anwer, Deepa Sreekanth Kaithavalappil, Esra Koca and Levent Yurdaer Aydemir

Gels 2023, 9(4), 337; https://doi.org/10.3390/gels9040337 - 15 Apr 2023

Cited by 15 | Viewed by 3465

Abstract

Several studies have reported the advantages of incorporating essential oils in hydrogel-based films for improving their physiochemical and antioxidant attributes. Cinnamon essential oil (CEO) has great potential in industrial and medicinal applications as an antimicrobial and antioxidant agent. The present study aimed to [...] Read more.

Several studies have reported the advantages of incorporating essential oils in hydrogel-based films for improving their physiochemical and antioxidant attributes. Cinnamon essential oil (CEO) has great potential in industrial and medicinal applications as an antimicrobial and antioxidant agent. The present study aimed to develop sodium alginate (SA) and acacia gum (AG) hydrogel-based films loaded with CEO. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), and texture analysis (TA) were performed to analyze the structural, crystalline, chemical, thermal, and mechanical behaviour of the edible films that were loaded with CEO. Moreover, the transparency, thickness, barrier, thermal, and color parameters of the prepared hydrogel-based films loaded with CEO were also assessed. The study revealed that as the concentration of oil in the films was raised, the thickness and elongation at break (EAB) increased, while transparency, tensile strength (TS), water vapor permeability (WVP), and moisture content (MC) decreased. As the concentration of CEO increased, the hydrogel-based films demonstrated a significant improvement in their antioxidant properties. Incorporating CEO into the SA–AG composite edible films presents a promising strategy for producing hydrogel-based films with the potential to serve as food packaging materials. Full article

(This article belongs to the Special Issue Bioactive Gel Films and Coatings Applied in Active Food Packaging)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Visual assessment of SA–AG-based composite edible films; AC-1/Control, AC-2 contains 15 μL of CEO, AC-3 contains 20 μL of CEO, and AC-4 contains 30 μL of CEO. Full article ">Figure 2
Scanning Electron Microscopy of SA–AG hydrogel-based edible films; AC-1/Control, AC-2 contains 15 μL of CEO, AC-3 contains 20 μL of CEO, and AC-4 contains 30 μL of CEO. Full article ">Figure 3
X-ray diffraction pattern of SA–AG hydrogel-based edible films; AC-1/blank, AC-2 contained 15 μL of CEO, AC-3 contained 20 μL of CEO, and AC-4 contained 30 μL of CEO. Full article ">Figure 4
FTIR spectrum of SA–AG hydrogel-based edible films; AC-1/Control, AC-2 contains 15 μL of CEO, AC-3 contains 20 μL of CEO and AC-4 contains 30 μL of CEO. Full article ">Figure 5
DSC analysis of SA–AG-based composite edible films; AC-1/Control, AC-2 contains 15 μL of CEO, AC-3 contains 20 μL of CEO, and AC-4 contains 30 μL of CEO. Full article ">Figure 6
Antioxidant activity of SA–AG-based composite edible films; AC-1/Control, AC-2 contains 15 μL of CEO, AC-3 contains 20 μL of CEO, and AC-4 contains 30 μL of CEO. Full article ">

15 pages, 6503 KiB

Open AccessEditor’s ChoiceArticle

Dehydrofluorination Process of Poly(vinylidene difluoride) PVdF-Based Gel Polymer Electrolytes and Its Effect on Lithium-Sulfur Batteries

by Julen Castillo, Adrián Robles-Fernandez, Rosalía Cid, José Antonio González-Marcos, Michel Armand, Daniel Carriazo, Heng Zhang and Alexander Santiago

Gels 2023, 9(4), 336; https://doi.org/10.3390/gels9040336 - 14 Apr 2023

Cited by 10 | Viewed by 3613

Abstract

Gel polymer electrolytes (GPEs) are emerging as suitable candidates for high-performing lithium-sulfur batteries (LSBs) due to their excellent performance and improved safety. Within them, poly(vinylidene difluoride) (PVdF) and its derivatives have been widely used as polymer hosts due to their ideal mechanical and [...] Read more.

Gel polymer electrolytes (GPEs) are emerging as suitable candidates for high-performing lithium-sulfur batteries (LSBs) due to their excellent performance and improved safety. Within them, poly(vinylidene difluoride) (PVdF) and its derivatives have been widely used as polymer hosts due to their ideal mechanical and electrochemical properties. However, their poor stability with lithium metal (Li⁰) anode has been identified as their main drawback. Here, the stability of two PVdF-based GPEs with Li⁰ and their application in LSBs is studied. PVdF-based GPEs undergo a dehydrofluorination process upon contact with the Li⁰. This process results in the formation of a LiF-rich solid electrolyte interphase that provides high stability during galvanostatic cycling. Nevertheless, despite their outstanding initial discharge, both GPEs show an unsuitable battery performance characterized by a capacity drop, ascribed to the loss of the lithium polysulfides and their interaction with the dehydrofluorinated polymer host. Through the introduction of an intriguing lithium salt (lithium nitrate) in the electrolyte, a significant improvement is achieved delivering higher capacity retention. Apart from providing a detailed study of the hitherto poorly characterized interaction process between PVdF-based GPEs and the Li⁰, this study demonstrates the need for an anode protection process to use this type of electrolytes in LSBs. Full article

(This article belongs to the Special Issue Gel-Based Electrolytes for Solid-State Electrochemical Devices)

► Show Figures

Figure 1

Figure 1
(a) Aging test of PEGDME_GPE in contact with Li0 anode. (b) ATR-FTIR spectra of the PEGDME_GPE-based electrolyte before and after being in contact with Li0 anode. (c) F 1s and C 1s regions corresponding XPS of the pristine PEGDME_GPE membrane and PEGDME_GPE after contact with Li0 anode. Full article ">Figure 2
(a) Galvanostatic cycling of Li0 symmetric cells using PEGDME-based (black) TEGDME-based (red) electrolytes under different current densities (from 0.05 mA cm−2 to 2 mA cm−2) and with 1h for the half cycle. (b) Galvanostatic cycling of Li0/PEGDME_GPE/Li0 (black) and Li0/TEGDME_GPE/Li0 (red) cells at 0.3 mA cm−2 and 0.3 mAh cm−2. (c) Electrochemical impedance spectroscopy (EIS) over time of Li0/PEGDME_GPE/Li0 (d) EIS over time of Li0/TEGDME_GPE/Li0. (e,f) Optical images and F 1s region corresponding XPS of the Li0 anode after the galvanostatic cycling with PEGDME_GPE and TEGDME_GPE, respectively. Full article ">Figure 3
(a,b) Charge/Discharge profiles for PEGDME_GPE and TEGDME_GPE Li-S cells, respectively. (c) battery performance of developed GPEs. (d) Optical post-mortem images of the analyzed GPEs and their corresponding Li0 anode. Full article ">Figure 4
(a) Schematic illustration of the behavior of the membrane towards the different cell compounds. (b) XPS of F 1s, C 1s, and S 2p of the GPE after the combination of the dehydrofluorination process of the GPE and the presence of LiPS. Full article ">Figure 5
(a) Comparison of the battery performance of PEGDME_GPE with and without LiNO3 additive and (b) their corresponding optical post-mortem analysis of the membranes and Li0 anodes. Full article ">

13 pages, 5587 KiB

Open AccessArticle

Ethyl Vanillin Rapid Crystallization from Carboxymethyl Chitosan Ion-Switchable Hydrogels

by Chenghong Huang, Hong Tang, Xiaorong Huang, Hongjie Chen, Kang Yang, Qi Yin, Lin Zhang, Xia Li, Xue Mou, Shuangkou Chen, Yuchan Zhang and Yan Hu

Gels 2023, 9(4), 335; https://doi.org/10.3390/gels9040335 - 14 Apr 2023

Viewed by 2163

Abstract

Polymer gels are usually used for crystal growth as the recovered crystals have better properties. Fast crystallization under nanoscale confinement holds great benefits, especially in polymer microgels as its tunable microstructures. This study demonstrated that ethyl vanillin can be quickly crystallized from carboxymethyl [...] Read more.

Polymer gels are usually used for crystal growth as the recovered crystals have better properties. Fast crystallization under nanoscale confinement holds great benefits, especially in polymer microgels as its tunable microstructures. This study demonstrated that ethyl vanillin can be quickly crystallized from carboxymethyl chitosan/ethyl vanillin co-mixture gels via classical swift cooling method and supersaturation. It found that EVA appeared with bulk filament crystals accelerated by a large quantity of nanoconfinement microregions resulted from space-formatted hydrogen network between EVA and CMCS when their concentration exceeds 1:1.4 and may occasionally arise when the concentration less than 1:0.8. It was observed that EVA crystal growth has two models involving hang-wall growth at the air-liquid interface at the contact line, as well as extrude-bubble growth at any sites on the liquid surface. Further investigations found that EVA crystals can be recovered from as-prepared ion-switchable CMCS gels by 0.1 M hydrochloric acid or acetic acid without defects. Consequently, the proposed method may offer an available scheme for a large-scale preparation of API analogs. Full article

(This article belongs to the Special Issue Recent Developments in Chitosan Hydrogels)

► Show Figures

Figure 1

Figure 1
EVA crystallization from CMCS gels with different concentration ratio (a1–a5 and b1–b3) in centrifuge tube (five repeats a1–a5) and ampoule bottle (three repeats b1–b3). Full article ">Figure 2
EVA hang-wall growth (a) at air/liquid interface or bulge growth (b,c) on liquid surface, and occasionally acquired linear EVA crystals (d) in CMCS/EVA con-mixture gels. Full article ">Figure 3
EVA crystal growth in CMCS/EVA co-mixture gels with appearances from leaves (a1–a6) to trees ramification (a7–a11). Full article ">Figure 4
EVA in CMCS sol. (a) growth pattern of EVA crystal in CMCS gels, (b) Free spherical growth in sol (blue arrow) or tree growth in CMCS gels (yellow arrow)), (c) Hydrophobic aggregation core of EVA in CMCS sol, (d) spherical aggregation of CMCS/EVA on silicon wafer surface; (e) 2 × 103 molecular weight CMCS forms loose velvet flower in CMCS sol (grey arrow); (f) dried state of velvet flower, (g) 15 × 104 molecular weight CMCS forms CMCS/EVA tree crystals in plate. Full article ">Figure 5
SEM images of dried CMCS/EVA with at 2 × 103 (a), 2 × 104 (b) and (c) 15 × 104 molecular weight, which are stirred in a magnetic mixer at 120 rpm for 15 days; (d) EVA precipitated with symmetrical shapes (e) dried d and (f) regular structure of e. Full article ">Figure 6
Irregular arrangement of CMCS blank gels (a) and regular arrangement of CMCS/EVA co-mixture gels (b) in SEM images. Full article ">Figure 7
EVA crystals were recovered from CMCS/EVA co-mixture gels. (a) EVA growth in CMCS gel, (b) 0.1M HCl hydrolyze CMCS gels, (c) EVA crystals float in CMCS solution and (d) EVA crystals recovered from membrane filtration. Full article ">Figure 8
FT-IR (A) and XRD (B) of LMW CMCS (ⅰ), CMCS (ⅱ), EVA (ⅲ), CMCS/EVA dried gel (ⅳ), EVA crystals (ⅴ, 25 °C obtained) and EVA crystals (ⅵ, 4 ℃ obtained). Detailed descriptions please see the text. Full article ">Scheme 1
Process chart of EVA crystallization from CMCS gels. Full article ">

13 pages, 3606 KiB

Open AccessArticle

Optimization of the Dose Rate Effect in Tetrazolium Gellan Gel Dosimeters

by Kalin I. Penev, Matt Mulligan and Kibret Mequanint

Gels 2023, 9(4), 334; https://doi.org/10.3390/gels9040334 - 14 Apr 2023

Cited by 3 | Viewed by 1483

Abstract

Tetrazolium salts provide an appealing candidate for 3D gel dosimeters as they exhibit a low intrinsic color, no signal diffusion and excellent chemical stability. However, a previously developed commercial product (the ClearView 3D Dosimeter) based on a tetrazolium salt dispersed within a gellan [...] Read more.

Tetrazolium salts provide an appealing candidate for 3D gel dosimeters as they exhibit a low intrinsic color, no signal diffusion and excellent chemical stability. However, a previously developed commercial product (the ClearView 3D Dosimeter) based on a tetrazolium salt dispersed within a gellan gum matrix presented a noticeable dose rate effect. The goal of this study was to find out whether ClearView could be reformulated in order to minimize the dose rate effect by optimizing of the tetrazolium salt and gellan gum concentrations and by the addition a thickening agent, ionic crosslinkers, and radical scavengers. To that goal, a multifactorial design of experiments (DOE) was conducted in small-volume samples (4-mL cuvettes). It showed that the dose rate could be effectively minimized without sacrificing the integrity, chemical stability, or dose sensitivity of the dosimeter. The results from the DOE were used to prepare candidate formulations for larger-scale testing in 1-L samples to allow for fine-tuning the dosimeter formulation and conducting more detailed studies. Finally, an optimized formulation was scaled-up to a clinically relevant volume of 2.7 L and tested against a simulated arc treatment delivery with three spherical targets (diameter 3.0 cm), requiring different doses and dose rates. The results showed excellent geometric and dosimetric registration, with a gamma passing rate (at 10% minimum dose threshold) of 99.3% for dose difference and distance to agreement criteria of 3%/2 mm, compared to 95.7% in the previous formulation. This difference may be of clinical importance, as the new formulation may allow the quality assurance of complex treatment plans, relying on a variety of doses and dose rates; thus, expanding the potential practical application of the dosimeter. Full article

(This article belongs to the Special Issue Gel-Based Drug Delivery Systems for Cancer Treatment)

► Show Figures

Figure 1

Figure 1
Combined effects of the tetrazolium salt (BNC) and gellan gum concentrations on the dosimetric properties of the gels. Panel A: background optical attenuation at 525 ± 5 nm; panel B: dose sensitivity, expressed as the change of attenuation per absorbed dose; panel C: rate of darkening of the gel while stored at room temperature, expressed as the rate of auto-reduction of the tetrazolium salt, measured as the change of the optical attenuation at 525 ± 5 nm vs. time; panel D: dose rate effect, expressed as the percentile difference in dose sensitivity when the gels were irradiated, using 6MV X-ray, at 600 or 100 cGy/min. Full article ">Figure 2
Effects of individual ingredients on the properties of the dosimeter: background optical attenuation, dose sensitivity, rate of auto-reduction and dose rate effect, as defined before, normalized to the control (formulation B1: 0.75% gellan gum and 0.25 mM BNC). Significantly different values (p < 0.05) in each category are shown by different letters from “a” to “d” in order of increasing magnitude. For example, the background attenuation was not significantly affected by the addition of methyl paraben (MP), while the addition of polyacrylamide (PAM), lithium lactate (LiLac) or lithium chloride (LiCl) increased the attenuation in the same order. It should be noted that the dose rate effect, which is a difference of sensitivities, is strongly affected by experimental uncertainties in small-scale samples, hence the large error bars. Full article ">Figure 3
Depth dose curves in 1-L volumes of formulations D1 to D3 using 6MV X-rays (2 × 2 cm2 field) as measured (open symbols) compared to the Monte-Carlo calculations (solid lines). The same y-axis scale was used in all cases to demonstrate the difference in sensitivity. Over the whole dose-depth curve, there was a relatively weak dependence between the measured and calculated results (R2 < 0.79), with a marked over-response in the dose build-up region, possibly due to the effect of dissolved oxygen near the surface of the gel. Below the depth of maximum dose (dmax = 1.6 cm), R2 reached above 0.998 for all cases. Full article ">Figure 4
Line profiles in gels from formulations A1 (original ClearView) and D2 (reformulated ClearView) through three spherical targets (T1–T3) with 30 mm diameter each and a calibration target T4 made from two square parallel-opposed beams of 2 × 2 cm2. The nominal doses and dose rates for each target were: T1: 20 Gy at 600 cGy/min, T2: 15 Gy at 300 cGy/min, T3: 10 Gy at 100 cGy/min, and T4: 20 Gy at 400 cGy/min. Full article ">Figure 5
3D maps of the dose treatment plan in cylindrical volumes (diameter 15 cm, height 12 cm), normalized to 20 Gy for formulations A1 and D2 (top). The nominal doses and dose rates for each target were: T1: 20 Gy at 600 cGy/min, T2: 15 Gy at 300 cGy/min, T3: 10 Gy at 100 cGy/min, and T4: 20 Gy at 400 cGy/min. Compared to isometric maps at γ > 1 (failing points) at percent dose-difference and distance to agreement of 3%/1 mm (middle) and 3%/2 mm (bottom) at 10% minimum dose threshold in the same volumes. Notably, while formulation A1 passes with 95.7% GPR at 3%/2 mm, low dose rate regions failed, including the whole volume T3, as well the build-up regions of T2 and T1; whereas, at the same criteria, formulation D2 passed everywhere except near the periphery of the volume. Full article ">

16 pages, 3908 KiB

Open AccessArticle

Homo- and Copolymer Hydrogels Based on N-Vinylformamide: An Investigation of the Impact of Water Structure on Controlled Release

by Maytinee Yooyod, Sukunya Ross, Premchirakorn Phewchan, Jinjutha Daengmankhong, Thanyaporn Pinthong, Nantaprapa Tuancharoensri, Sararat Mahasaranon, Jarupa Viyoch and Gareth M. Ross

Gels 2023, 9(4), 333; https://doi.org/10.3390/gels9040333 - 14 Apr 2023

Cited by 4 | Viewed by 2237

Abstract

This study investigated the performance of novel hydrogels based on poly (N-vinylformamide) (PNVF), copolymers of NVF with N-hydroxyethyl acrylamide (HEA) (P(NVF-co-HEA)), and 2-carboxyethyl acrylate (CEA) (P(NVF-co-CEA)), which were synthesized by photopolymerization using a UVLED light source. The hydrogels were analyzed for important properties [...] Read more.

This study investigated the performance of novel hydrogels based on poly (N-vinylformamide) (PNVF), copolymers of NVF with N-hydroxyethyl acrylamide (HEA) (P(NVF-co-HEA)), and 2-carboxyethyl acrylate (CEA) (P(NVF-co-CEA)), which were synthesized by photopolymerization using a UVLED light source. The hydrogels were analyzed for important properties such as equilibrium water content (%EWC), contact angle, freezing and non-freezing water, and diffusion-based in vitro release. The results showed that PNVF had an extremely high %EWC of 94.57%, while a decreasing NVF content in the copolymer hydrogels led to a decrease in water content with a linear relationship with HEA or CEA content. Water structuring in the hydrogels showed appreciably more variance, with ratios of free to bound water differing from 16.7:1 (NVF) to 1.3:1 (CEA), corresponding to PNVF having ~67 water molecules per repeat unit. The release studies of different dye molecules followed Higuchi’s model, with the amount of dye released from the hydrogels depending on the amount of free water and the structural interactions between the polymer and the molecule being released. The results suggest that PNVF copolymer hydrogels have potential for controlled drug delivery by altering the polymer composition to govern the amount and ratio of free to bound water contained in the hydrogels. Full article

(This article belongs to the Section Gel Applications)

► Show Figures

Figure 1

12 pages, 5789 KiB

Open AccessArticle

Synthesis and Characterization of a Novel Composite Edible Film Based on Hydroxypropyl Methyl Cellulose Grafted with Gelatin

by Yajuan Wang, Shuting Jiang, Yue Chen, Dan Qiu and Yunxuan Weng

Gels 2023, 9(4), 332; https://doi.org/10.3390/gels9040332 - 14 Apr 2023

Cited by 9 | Viewed by 2581

Abstract

A novel composite edible film was synthesized by grafting gelatin chain onto hydroxypropyl methyl cellulose (HPMC) in the presence of glycerol (used as a plasticizer) using a solution polymerization technique. The reaction was carried out in homogeneous aqueous medium. Thermal properties, chemical structure, [...] Read more.

A novel composite edible film was synthesized by grafting gelatin chain onto hydroxypropyl methyl cellulose (HPMC) in the presence of glycerol (used as a plasticizer) using a solution polymerization technique. The reaction was carried out in homogeneous aqueous medium. Thermal properties, chemical structure, crystallinity, surface morphology, and mechanical and hydrophilic performance changes of HPMC caused by the addition of gelatin were investigated by differential scanning calorimetry, thermogravimetric, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, universal testing machine and water contact angle. The results shows that HPMC and gelatin are miscible and the hydrophobic property of the blending film can be enhanced with the introduction of the gelatin. Moreover, the HPMC/gelatin blend films are flexible, and exhibit excellent compatibility, good mechanical properties and also thermal stability, and could be promising candidates for food packaging materials. Full article

(This article belongs to the Special Issue Food Gels: Structure and Properties)

► Show Figures

Graphical abstract

20 pages, 2506 KiB

Open AccessReview

Nano-Gels: Recent Advancement in Fabrication Methods for Mitigation of Skin Cancer

by Ghallab Alotaibi, Sitah Alharthi, Biswajit Basu, Dipanjana Ash, Swarnali Dutta, Sudarshan Singh, Bhupendra G. Prajapati, Sankha Bhattacharya, Vijay R. Chidrawar and Havagiray Chitme

Gels 2023, 9(4), 331; https://doi.org/10.3390/gels9040331 - 13 Apr 2023

Cited by 11 | Viewed by 3419

Abstract

In the 21st century, melanoma and non-melanoma skin cancers have become an epidemic outbreak worldwide. Therefore, the exploration of all potential preventative and therapeutic measures based on either physical or bio-chemical mechanisms is essential via understanding precise pathophysiological pathways (Mitogen-activated protein kinase, Phosphatidylinositol [...] Read more.

In the 21st century, melanoma and non-melanoma skin cancers have become an epidemic outbreak worldwide. Therefore, the exploration of all potential preventative and therapeutic measures based on either physical or bio-chemical mechanisms is essential via understanding precise pathophysiological pathways (Mitogen-activated protein kinase, Phosphatidylinositol 3-kinase Pathway, and Notch signaling pathway) and other aspects of such skin malignancies. Nano-gel, a three-dimensional polymeric cross-linked porous hydrogel having a diameter of 20–200 nm, possesses dual properties of both hydrogel and nanoparticle. The capacity of high drug entrapment efficiency with greater thermodynamic stability, remarkable solubilization potential, and swelling behavior of nano-gel becomes a promising candidate as a targeted drug delivery system in the treatment of skin cancer. Nano-gel can be either synthetically or architectonically modified for responding to either internal or external stimuli, including radiation, ultrasound, enzyme, magnetic, pH, temperature, and oxidation-reduction to achieve controlled release of pharmaceuticals and several bio-active molecules such as proteins, peptides, genes via amplifying drug aggregation in the active targeted tissue and reducing adverse pharmacological effects. Several drugs, such as anti-neoplastic biomolecules having short biological half-lives and prompt enzyme degradability capacity, must be appropriate for administration employing either chemically bridged or physically constructed nano-gel frameworks. The comprehensive review summarizes the advancement in the preparation and characterization methods of targeted nano-gel with enhanced pharmacological potential and preserved intracellular safety limits for the mitigation of skin malignancies with a special emphasize on skin cancer inducing pathophysiological pathways and prospective research opportunities for skin malignancy targeted nano-gels. Full article

(This article belongs to the Special Issue Engineering Advanced Hydrogels for Biomedical Applications)

► Show Figures

Figure 1

13 pages, 3211 KiB

Open AccessArticle

Nanoarchitectonics of a Skin-Adhesive Hydrogel Based on the Gelatin Resuscitation Fluid Gelatinol^®

by Konstantin Osetrov, Mayya Uspenskaya, Faliya Zaripova and Roman Olekhnovich

Gels 2023, 9(4), 330; https://doi.org/10.3390/gels9040330 - 13 Apr 2023

Cited by 4 | Viewed by 1585

Abstract

Hydrogel materials are one of the most versatile representatives of biomaterials. Their widespread use in medical practice is due to their similarity to native biostructures regarding relevant properties. This article discusses the synthesis of hydrogels based on a plasma-substituting Gelatinol^® solution and [...] Read more.

Hydrogel materials are one of the most versatile representatives of biomaterials. Their widespread use in medical practice is due to their similarity to native biostructures regarding relevant properties. This article discusses the synthesis of hydrogels based on a plasma-substituting Gelatinol^® solution and modified tannin, carried out by direct mixing of the two solutions and brief heating. This approach makes it possible to obtain materials based on precursors that are safe for humans, while having antibacterial activity and high adhesion to human skin. Thanks to the synthesis scheme used, it is possible to obtain hydrogels with a complex shape before use, which is relevant in cases where industrial hydrogels do not fully satisfy the end use regarding their form factor. Using IR spectroscopy and thermal analysis, the distinctive aspects of mesh formation were shown in comparison with the hydrogels based on ordinary gelatin. A number of application properties, such as the physical and mechanical characteristics, permeability to oxygen/moisture, and antibacterial effect, were also considered. The sorption parameters of the material were characterized in a set of physiological buffers (pH 2–9) using Fick’s first law and a pseudo-second order equation. The adhesive shear strength was determined in a model system. The synthesized hydrogels showed potential for the further development of materials based on plasma-substituting solutions. Full article

► Show Figures

Graphical abstract

23 pages, 4137 KiB

Open AccessArticle

Temperature-Responsive Hydrogel for Silver Sulfadiazine Drug Delivery: Optimized Design and In Vitro/In Vivo Evaluation

by Maha Mohammad AL-Rajabi and Yeit Haan Teow

Gels 2023, 9(4), 329; https://doi.org/10.3390/gels9040329 - 13 Apr 2023

Cited by 3 | Viewed by 2210

Abstract

Response surface methodology (RSM) was applied to optimise a temperature-responsive hydrogel formulation synthesised via the direct incorporation of biocellulose, which was extracted from oil palm empty fruit bunches (OPEFB) using the PF127 method. The optimised temperature-responsive hydrogel formulation was found to contain 3.000 [...] Read more.

Response surface methodology (RSM) was applied to optimise a temperature-responsive hydrogel formulation synthesised via the direct incorporation of biocellulose, which was extracted from oil palm empty fruit bunches (OPEFB) using the PF127 method. The optimised temperature-responsive hydrogel formulation was found to contain 3.000 w/v% biocellulose percentage and 19.047 w/v% PF127 percentage. The optimised temperature-responsive hydrogel provided excellent LCST near to the human body surface temperature, with high mechanical strength, drug release duration, and inhibition zone diameter against Staphylococcus aureus. Moreover, in vitro cytotoxicity testing against human epidermal keratinocyte (HaCaT) cells was conducted to evaluate the toxicity of the optimised formula. It was found that silver sulfadiazine (SSD)-loaded temperature-responsive hydrogel can be used as a safe replacement for the commercial SSD cream with no toxic effect on HaCaT cells. Last, but not least, in vivo (animal) dermal testing—both dermal sensitization and animal irritation—were conducted to evaluate the safety and biocompatibility of the optimised formula. No sensitization effects were detected on the skin applied with SSD-loaded temperature-responsive hydrogel indicating no irritant response for topical application. Therefore, the temperature-responsive hydrogel produced from OPEFB is ready for the next stage of commercialisation. Full article

(This article belongs to the Special Issue Hydrogels in Action: Self-Assembly, Responsivity and Sensing)

► Show Figures

Figure 1

21 pages, 5442 KiB

Open AccessArticle

Synthesis and Characterization of Biodegradable Poly(vinyl alcohol)-Chitosan/Cellulose Hydrogel Beads for Efficient Removal of Pb(II), Cd(II), Zn(II), and Co(II) from Water

by Mona A. Aziz Aljar, Suad Rashdan, Abdulla Almutawah and Ahmed Abd El-Fattah

Gels 2023, 9(4), 328; https://doi.org/10.3390/gels9040328 - 13 Apr 2023

Cited by 14 | Viewed by 3090

Abstract

Globally, water contamination by heavy metals is a serious problem that affects the environment and human health. Adsorption is the most efficient way of water treatment for eliminating heavy metals. Various hydrogels have been prepared and used as adsorbents to remove heavy metals. [...] Read more.

Globally, water contamination by heavy metals is a serious problem that affects the environment and human health. Adsorption is the most efficient way of water treatment for eliminating heavy metals. Various hydrogels have been prepared and used as adsorbents to remove heavy metals. By taking advantage of poly(vinyl alcohol) (PVA), chitosan (CS), cellulose (CE), and the process for physical crosslinking, we propose a simple method to prepare a PVA-CS/CE composite hydrogel adsorbent for the removal of Pb(II), Cd(II), Zn(II) and Co(II) from water. Structural analyses of the adsorbent were examined by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis, and X-ray diffraction (XRD). PVA-CS/CE hydrogel beads had a good spherical shape together with a robust structure and suitable functional groups for the adsorption of heavy metals. The effects of adsorption parameters such as pH, contact time, adsorbent dose, initial concentration of metal ions, and temperature on the adsorption capacity of PVA-CS/CE adsorbent were studied. The adsorption characteristics of PVA-CS/CE for heavy metals may be completely explained by pseudo-second-order adsorption and the Langmuir adsorption model. The removal efficiency of PVA-CS/CE adsorbent for Pb(II), Cd(II), Zn(II), and Co(II) was 99, 95, 92, and 84%, respectively, within 60 min. The heavy metal’s hydrated ionic radius may be crucial in determining the adsorption preference. After five consecutive adsorption–desorption cycles, the removal efficiency remained over 80%. As a result, the outstanding adsorption-desorption properties of PVA-CS/CE can potentially be extended to industrial wastewater for heavy metal ion removal. Full article

(This article belongs to the Special Issue Synthesis and Applications of Hydrogels)

► Show Figures

Figure 1

12 pages, 1029 KiB

Open AccessArticle

Application of Unsupervised Learning for the Evaluation of Aerogels’ Efficiency towards Dye Removal—A Principal Component Analysis (PCA) Approach

by Khaled Younes, Yahya Kharboutly, Mayssara Antar, Hamdi Chaouk, Emil Obeid, Omar Mouhtady, Mahmoud Abu-samha, Jalal Halwani and Nimer Murshid

Gels 2023, 9(4), 327; https://doi.org/10.3390/gels9040327 - 12 Apr 2023

Cited by 10 | Viewed by 1868

Abstract

Water scarcity is a growing global issue, particularly in areas with limited freshwater sources, urging for sustainable water management practices to insure equitable access for all people. One way to address this problem is to implement advanced methods for treating existing contaminated water [...] Read more.

Water scarcity is a growing global issue, particularly in areas with limited freshwater sources, urging for sustainable water management practices to insure equitable access for all people. One way to address this problem is to implement advanced methods for treating existing contaminated water to offer more clean water. Adsorption through membranes technology is an important water treatment technique, and nanocellulose (NC)-, chitosan (CS)-, and graphene (G)- based aerogels are considered good adsorbents. To estimate the efficiency of dye removal for the mentioned aerogels, we intend to use an unsupervised machine learning approach known as “Principal Component Analysis”. PCA showed that the chitosan-based ones have the lowest regeneration efficiencies, along with a moderate number of regenerations. NC2, NC9, and G5 are preferred where there is high adsorption energy to the membrane, and high porosities could be tolerated, but this allows lower removal efficiencies of dye contaminants. NC3, NC5, NC6, and NC11 have high removal efficiencies even with low porosities and surface area. In brief, PCA presents a powerful tool to unravel the efficiency of aerogels towards dye removal. Hence, several conditions need to be considered when employing or even manufacturing the investigated aerogels. Full article

(This article belongs to the Section Gel Applications)

► Show Figures

Figure 1

20 pages, 3723 KiB

Open AccessArticle

Injectable Hydrogels Based on Cyclodextrin/Cholesterol Inclusion Complexation and Loaded with 5-Fluorouracil/Methotrexate for Breast Cancer Treatment

by Saud Almawash, Ahmed M. Mohammed, Mohamed A. El Hamd and Shaaban K. Osman

Gels 2023, 9(4), 326; https://doi.org/10.3390/gels9040326 - 12 Apr 2023

Cited by 3 | Viewed by 2047

Abstract

Breast cancer is the second most common cancer in women worldwide. Long-term treatment with conventional chemotherapy may result in severe systemic side effects. Therefore, the localized delivery of chemotherapy helps to overcome such a problem. In this article, self-assembling hydrogels were constructed via [...] Read more.

Breast cancer is the second most common cancer in women worldwide. Long-term treatment with conventional chemotherapy may result in severe systemic side effects. Therefore, the localized delivery of chemotherapy helps to overcome such a problem. In this article, self-assembling hydrogels were constructed via inclusion complexation between host β-cyclodextrin polymers (8armPEG20k-CD and pβ-CD) and the guest polymers 8-armed poly(ethylene glycol) capped either with cholesterol (8armPEG20k-chol) or adamantane (8armPEG20k-Ad) and were loaded with 5-fluorouracil (5-FU) and methotrexate (MTX). The prepared hydrogels were characterized by SEM and rheological behaviors. The in vitro release of 5-FU and MTX was studied. The cytotoxicity of our modified systems was investigated against breast tumor cells (MCF-7) using an MTT assay. Additionally, the histopathological changes in breast tissues were monitored before and after their intratumor injection. The results of rheological characterization indicated the viscoelastic behavior in all cases except for 8armPEG-Ad. In vitro release results showed a variable range of release profiles from 6 to 21 days, depending on the hydrogel composition. MTT findings indicated the inhibition ability of our systems against the viability of cancer cells depending on the kind and concentration of the hydrogel and the incubation period. Moreover, the results of histopathology showed the improvement of cancer manifestation (swelling and inflammation) after intratumor injection of loaded hydrogel systems. In conclusion, the obtained results indicated the applicability of the modified hydrogels as injectable vehicles for both loading and controlled release of anticancer therapies. Full article

(This article belongs to the Special Issue Cancer Cell Biology in Biological Hydrogel)

► Show Figures

Figure 1

12 pages, 455 KiB

Open AccessArticle

The Effect of Hyaluronic Acid Gel on Periodontal Parameters, Pro-Inflammatory Cytokines and Biochemical Markers in Periodontitis Patients

by Chenar Anwar Mohammad, Barzan Abdulwahab Mirza, Zainab Salim Mahmood and Faraedon Mostafa Zardawi

Gels 2023, 9(4), 325; https://doi.org/10.3390/gels9040325 - 12 Apr 2023

Cited by 6 | Viewed by 3465

Abstract

Hyaluronic acid in its various forms shows bacteriostatic, fungistatic, anti-inflammatory, anti-edematous, osteoinductive, and pro-angiogenetic properties. This study aimed to evaluate the effect of subgingival delivery of 0.8% hyaluronic acid (HA) gel on clinical periodontal parameters, pro-inflammatory cytokines (IL-1 beta and TNF-alpha) and biochemical [...] Read more.

Hyaluronic acid in its various forms shows bacteriostatic, fungistatic, anti-inflammatory, anti-edematous, osteoinductive, and pro-angiogenetic properties. This study aimed to evaluate the effect of subgingival delivery of 0.8% hyaluronic acid (HA) gel on clinical periodontal parameters, pro-inflammatory cytokines (IL-1 beta and TNF-alpha) and biochemical markers of inflammation (C-reactive protein (CRP) and alkaline phosphatase (ALP) enzymes) in patients with periodontitis. Seventy-five patients with chronic periodontitis were divided randomly into three groups (25 in each group): group I received scaling and surface root debridement (SRD) + HA gel; group II received SRD + chlorhexidine gel; and group III received surface root debridement alone. Clinical periodontal parameter measurements and blood samples were collected to estimate pro-inflammatory and biochemical parameters at the baseline before therapy and after two months of therapy. The results show that HA gel has a significant effect on the reduction in clinical periodontal parameters (PI, GI, BOP, PPD, and CAL), IL-1 beta, TNF-alpha, CRP, and ALP after 2 months of therapy as compared to the baseline (p < 0.05) with nonsignificant differences from the CHX group (p > 0.05), except GI (p < 0.05), and significant differences from the SRD group (p < 0.05). Moreover, significant differences were found between the three groups regarding the mean improvements of GI, BOP, PPD, IL-1β, CRP, and ALP. It can be concluded that HA gel has a positive effect on clinical periodontal parameters and improvements in inflammatory mediators similar to chlorhexidine. Therefore, HA gel can be used as an adjuvant to SRD in the treatment of periodontitis. Full article

(This article belongs to the Special Issue Advanced Gels for Drug Delivery Systems Based on Sustainable Development Goals (SDGs))

► Show Figures

Figure 1

12 pages, 3341 KiB

Open AccessArticle

Spatial-Temporal Heterogeneity in Large Three-Dimensional Nanofibrillar Cellulose Hydrogel for Human Pluripotent Stem Cell Culture

by Jin Hao, Ying Chen, Mingjian Zhu, Yingqing Zhao, Kai Zhang and Xia Xu

Gels 2023, 9(4), 324; https://doi.org/10.3390/gels9040324 - 12 Apr 2023

Cited by 1 | Viewed by 1840

Abstract

One approach to cell expansion is to use large hydrogel for growing a large number of cells. Nanofibrillar cellulose (NFC) hydrogel has been used for human induced pluripotent stem cell (hiPSCs) expansion. However, little is known about the status of hiPSCs at the [...] Read more.

One approach to cell expansion is to use large hydrogel for growing a large number of cells. Nanofibrillar cellulose (NFC) hydrogel has been used for human induced pluripotent stem cell (hiPSCs) expansion. However, little is known about the status of hiPSCs at the single cell level inside large NFC hydrogel during culture. To understand the effect of NFC hydrogel property on temporal–spatial heterogeneity, hiPSCs were cultured in 0.8 wt% NFC hydrogel with different thicknesses with the top surface exposed to the culture medium. The prepared hydrogel exhibits less restriction in mass transfer due to the presence of macropores and micropores interconnecting the macropores. More than 85% of cells at different depths survive after 5 days of culture inside 3.5 mm thick hydrogel. Biological compositions at different zones inside the NFC gel were examined over time at a single-cell level. A dramatic concentration gradient of growth factors estimated in the simulation along 3.5 mm NFC hydrogel could be a reason for the spatial–temporal heterogeneity in protein secondary structure and protein glycosylation and pluripotency loss at the bottom zone. pH change caused by the lactic acid accumulation over time leads to changes in cellulose charge and growth factor potential, probably another reason for the heterogeneity in biochemical compositions. This study may help to develop optimal conditions for producing high-quality hiPSCs in large nanofibrillar cellulose hydrogel at scale. Full article

► Show Figures

Figure 1

Figure 1
Characterization (a) XRD of Nanofibrillar cellulose (b) SEM images of NFC hydrogel (0.8 wt%) at different magnifications. Full article ">Figure 2
Cell morphology and viability after 5 days of culture. (a) Scheme for construction of NFC hydrogel embedded with hiPSCs. (b) Typical images for cell morphology on days 1, 3, and 5. (c) Typical images for cell viability at different zones at the end of 5 days of culture. (d) Cell viability at different zones on day 5. Error bars denote the means ± SEM. Full article ">Figure 3
Average second derivative spectra and principal component analysis for cells during culture. (a) Average second derivative spectra of the cells at different zone on days 1, 3, and 5. (b) The representative score plots of the PCA of hPSCs at different zones in 3D hydrogel during culture on days 1, 3, and 5. (c) The loading plots of the PCA for hPSCs cultured on days 1, 3, and 5. Full article ">Figure 4
Human iPSC stemness at different locations on day 5 cultured in 3D hydrogel. Error bars denote the means ± SEM. Statistical analyses were performed by unpaired Student’s t-test (* p < 0.05). Full article ">Figure 5
Solute distribution inside 3D hydrogel at different times and locations. Full article ">

15 pages, 6139 KiB

Open AccessArticle

A Nanoclay-Enhanced Hydrogel for Self-Adhesive Wearable Electrophysiology Electrodes with High Sensitivity and Stability

by Fushuai Wang, Lang Yang, Ye Sun, Yiming Cai, Xin Xu, Zhenzhong Liu, Qijie Liu, Hongliang Zhao, Chunxin Ma and Jun Liu

Gels 2023, 9(4), 323; https://doi.org/10.3390/gels9040323 - 11 Apr 2023

Cited by 8 | Viewed by 2646

Abstract

Hydrogel-based wet electrodes are the most important biosensors for electromyography (EMG), electrocardiogram (ECG), and electroencephalography (EEG); but, are limited by poor strength and weak adhesion. Herein, a new nanoclay-enhanced hydrogel (NEH) has been reported, which can be fabricated simply by dispersing nanoclay sheets [...] Read more.

Hydrogel-based wet electrodes are the most important biosensors for electromyography (EMG), electrocardiogram (ECG), and electroencephalography (EEG); but, are limited by poor strength and weak adhesion. Herein, a new nanoclay-enhanced hydrogel (NEH) has been reported, which can be fabricated simply by dispersing nanoclay sheets (Laponite XLS) into the precursor solution (containing acrylamide, N, N′-Methylenebisacrylamide, ammonium persulfate, sodium chloride, glycerin) and then thermo-polymerizing at 40 °C for 2 h. This NEH, with a double-crosslinked network, has nanoclay-enhanced strength and self-adhesion for wet electrodes with excellent long-term stability of electrophysiology signals. First of all, among existing hydrogels for biological electrodes, this NEH has outstanding mechanical performance (93 kPa of tensile strength and 1326% of breaking elongation) and adhesion (14 kPa of adhesive force), owing to the double-crosslinked network of the NEH and the composited nanoclay, respectively. Furthermore, this NEH can still maintain a good water-retaining property (it can remain at 65.4% of its weight after 24 h at 40 °C and 10% humidity) for excellent long-term stability of signals, on account of the glycerin in the NEH. In the stability test of skin–electrode impedance at the forearm, the impedance of the NEH electrode can be stably kept at about 100 kΩ for more than 6 h. As a result, this hydrogel-based electrode can be applied for a wearable self-adhesive monitor to highly sensitively and stably acquire EEG/ECG electrophysiology signals of the human body over a relatively long time. This work provides a promising wearable self-adhesive hydrogel-based electrode for electrophysiology sensing; which, will also inspire the development of new strategies to improve electrophysiological sensors. Full article

(This article belongs to the Special Issue Bio-Inspired Polymeric Gels and Their Applications)

► Show Figures

Figure 1

22 pages, 5096 KiB

Open AccessArticle

Formulation Development, Optimization by Box–Behnken Design, and In Vitro and Ex Vivo Characterization of Hexatriacontane-Loaded Transethosomal Gel for Antimicrobial Treatment for Skin Infections

by Alhussain H. Aodah, Sana Hashmi, Naseem Akhtar, Zabih Ullah, Ameeduzzafar Zafar, Randa Mohammed Zaki, Shamshir Khan, Mohammad Javed Ansari, Talha Jawaid, Aftab Alam and Md Sajid Ali

Gels 2023, 9(4), 322; https://doi.org/10.3390/gels9040322 - 11 Apr 2023

Cited by 17 | Viewed by 3204

Abstract

There are many different infections and factors that can lead to skin illnesses, but bacteria and fungi are the most frequent. The goal of this study was to develop a hexatriacontane-loaded transethosome (HTC-TES) for treating skin conditions caused by microbes. The HTC-TES was [...] Read more.

There are many different infections and factors that can lead to skin illnesses, but bacteria and fungi are the most frequent. The goal of this study was to develop a hexatriacontane-loaded transethosome (HTC-TES) for treating skin conditions caused by microbes. The HTC-TES was developed utilizing the rotary evaporator technique, and Box–Behnken design (BBD) was utilized to improve it. The responses chosen were particle size (nm) (Y1), polydispersity index (PDI) (Y2), and entrapment efficiency (Y3), while the independent variables chosen were lipoid (mg) (A), ethanol (%) (B), and sodium cholate (mg) (C). The optimized TES formulation with code F1, which contains lipoid (mg) (A) 90, ethanol (%) (B) 25, and sodium cholate (mg) (C) 10, was chosen. Furthermore, the generated HTC-TES was used for research on confocal laser scanning microscopy (CLSM), dermatokinetics, and in vitro HTC release. The results of the study reveal that the ideal formulation of the HTC-loaded TES had the following characteristics: 183.9 nm, 0.262 mV, −26.61 mV, and 87.79% particle size, PDI, and entrapment efficiency, respectively. An in vitro study on HTC release found that the rates of HTC release for HTC-TES and conventional HTC suspension were 74.67 ± 0.22 and 38.75 ± 0.23, respectively. The release of hexatriacontane from TES fit the Higuchi model the best, and the Korsmeyer–Peppas model indicates the release of HTC followed a non-Fickian diffusion. By having a higher negative value for cohesiveness, the produced gel formulation demonstrated its stiffness, whereas good spreadability indicated better gel application to the surface. In a dermatokinetics study, it was discovered that TES gel considerably increased HTC transport in the epidermal layers (p < 0.05) when compared to HTC conventional formulation gel (HTC-CFG). The CLSM of rat skin treated with the rhodamine B-loaded TES formulation demonstrated a deeper penetration of 30.0 µm in comparison to the hydroalcoholic rhodamine B solution (0.15 µm). The HTC-loaded transethosome was determined to be an effective inhibitor of pathogenic bacterial growth (S. aureus and E. coli) at a concentration of 10 mg/mL. It was discovered that both pathogenic strains were susceptible to free HTC. According to the findings, HTC-TES gel can be employed to enhance therapeutic outcomes through antimicrobial activity. Full article

(This article belongs to the Special Issue Designing Gels for Antibacterial Agents)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Gels, Volume 9, Issue 4 (April 2023) – 89 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI