Search Results (464)

Alzheimer’s disease (AD) is a highly prevalent neurodegenerative disease hallmarked by amyloid plaques and neurofibrillary tangles. Amyloid plaques are formed by the amyloid β (Aβ) aggregation, so substances that inhibit this aggregation are useful for preventing and treating AD. Mushrooms are widely used medicinal fungi with high edible and nutritional value. Mushrooms have a variety of biologically active ingredients, and studies have shown that they have certain effects in anti-bacterial, anti-oxidation, anti-inflammatory, anti-tumor, and immune regulation. Previously, we developed a microliter-scale high-throughput screening (MSHTS) system using quantum dot (QD) nanoprobes to screen Aβ aggregation inhibitors. In this study, we appraised the Aβ aggregation inhibitory activity of 210 natural mushrooms from Hokkaido (Japan) and found 11 samples with high activity. We then selected Elfvingia applanata and Fuscoporia obliqua for extraction and purification as these samples were able to suppress Aβ-induced neurocytotoxicity and were readily available in large quantities. We found that the ethyl acetate (EtOAc) extract of E. applanata has high Aβ aggregation inhibitory activity, so we performed silica gel column chromatography fractionation and found that fraction 5 (f5) of the EtOAc extract displayed the highest Aβ aggregation inhibitory activity among all mushroom samples. The half-maximal effective concentration (EC₅₀) value was 2.30 µg/mL, higher than the EC₅₀ of 10.7 µg/mL for rosmarinic acid, a well-known Aβ aggregation inhibitor. This inhibitory activity decreased with further purification, suggesting that some compounds act synergistically. The f5 fraction also inhibited the deposition of Aβ aggregates on the cell surface of human neuroblastoma SH-SY5Y cells. Our expectation is that f5, with additional tests, may eventually prove to be an inhibitor for the prevention of AD. Full article

In this study, three stainless steel materials (17-4PH, 316L, and 304) were experimentally simulated using metal injection molding (MIM) technology to explore the size shrinkage behavior and defect formation mechanism of materials with different particle sizes during sintering. The sintering environment was linearly heated to 1250 °C at a rate of 5 °C/min and kept warm for 90 min. Multi-physics field coupling analysis was performed using ANSYS Workbench software. Two different regions were selected to simulate the total deformation trend of the material during sintering. The simulation results were compared with data from SEM and EDS analyses to elucidate the influence of particle size on shrinkage behavior and defect distribution. The findings indicate that the gaps between particles far away from the gate position became larger, the degree of densification decreased, the porosity was higher, and the number of white dot inclusions increased. Among the three materials, 17-4PH, which had the smallest particle size, had a greater sintering driving force, a better degree of densification, a smaller predicted total deformation, and a higher shrinkage rate, which is consistent with the hardness test data and the actual density data. In addition, the densification advantage of small particle size powder is not only related to surface energy but is also closely linked to the uniformity of its microstructure. The analysis in this study further promotes the performance optimization of stainless steel materials, indicates a scientific basis for future process improvements and high-precision parts manufacturing in MIM technology, and points to the development direction for high-performance materials. Full article

Developing new nanomaterials and performing functionalization to increase their photocatalytic capacity are essential in developing low-cost, eco-friendly, and multipurpose-capacity catalysts. In this research, SnO₂/Se-doped quantum dots (QDs) covered with glycerol (SnO₂/Se-GLY) were synthesized using microwave irradiation. Then, their cover was replaced with glutaraldehyde through a ligand exchange procedure (SnO₂/Se-GLUT). The XRD analyses confirmed a tetragonal rutile structure of SnO₂. The HR-TEM analysis confirmed the generation of QDs with a size around 8 nm, and the optical analysis evidenced low bandgap energies of 3.25 and 3.26 eV for the SnO₂/Se-GLY and SnO₂/Se-GLUT QDs, respectively. Zeta-sizer analysis showed that the hydrodynamic sizes for both nanoparticles were around 230 nm (50 mg/L), and the zeta potential confirmed that SnO₂/Se-GLUT QDs were more stable than SnO₂/Se-GLY QDs. The cover-modified QDs (SnO₂/Se-GLUT) showed a higher and faster adsorption capacity, followed by a slower photocatalytic process than the original QDs (SnO₂/Se-GLY). The QTOF-LC-MS analysis confirmed MB degradation through the identification of intermediates such as azure A, azure B, azure C, and phenothiazine. Adsorption isotherm analysis indicated Langmuir model compliance, supporting the high monolayer adsorption capacity and efficiency of these QDs as adsorbent/photocatalytic agents for organic pollutant removal. This dual capability for adsorption and photodegradation, along with the demonstrated reusability, highlights the potential of SnO₂/Se QDs in wastewater treatment and environmental remediation. Full article

Background: Ocular predominant mucous membrane pemphigoid (oMMP) is a severe subtype of autoimmune blistering disease (AIBD), which can result in scarring and vision loss. The diagnosis of oMMP is challenging as patients often have undetectable levels of circulating autoantibodies by conventional assays. Likewise, the principal autoantigen in oMMP has been an area of debate. Methods: In this preliminary experiment, we performed Phage Immunoprecipitation Sequencing (PhIP-seq) on sera from patients with oMMP, as well as non-ocular MMP, bullous pemphigoid, and mucocutaneous-type pemphigus vulgaris. Results: We identified several autoantigens unique to oMMP relative to other AIBDs. We then cross-referenced these antigens against previously published single-nuclei datasets, as well as the International Mouse Phenotyping Consortium Database. Several protein hits identified in our study demonstrated enriched expression on the anterior surface epithelia, including TNKS1BP1, SEC16B, FNBP4, CASZ1, GOLGB1, DOT1L, PRDM 15, LARP4B, and RPL6. Likewise, a previous study of mouse knockout models of murine analogs CASZ1, HIP1, and ELOA2 reported that these mice showed abnormalities in terms of the ocular surface and development in the eyes. Notably, PhIP-seq failed to identify the canonical markers of AIBDs such as BP180, BP230, desmogleins 1 and 3, or integrin β4, indicating that the patient autoantibodies react with conformational epitopes rather than linear epitopes. Conclusions: oMMP patients demonstrate a unique autoantibody repertoire relative to the other AIBDs. Further validation of the identified autoantibodies will shed light on their potentially pathogenic role. Full article

The issue of the qualitative and quantitative analysis of the concentration of oxidising species in aquatic environments is crucial for a wide range of biological and environmental tasks. In particular, reactive chlorine species, specifically hypochlorite (ClO⁻), play a significant biochemical role in the operation of the immune system. There is also the challenge of determining the presence of ClO⁻ in purified drinking water that is supplied by water treatment systems. Traditional chemical analytical methods often lack the required selectivity and sensitivity to detect oxidising compounds, and chemiluminescence-based techniques offer an alternative solution. In this study, we propose a simple and selective approach for the chemiluminescent detection of hypochlorite in aqueous media under neutral conditions. The technique is based on measuring a chemiluminescent signal generated in the presence of hypochlorite by a combined probe comprising commercially available WS₂ quantum dots and luminol. The oxidation of WS₂ with hypochlorite followed by a reaction with luminol results in an intense luminescent signal that enables the selective determination of hypochlorite under neutral conditions. The greatest sensitivity with this method was achieved when combining WS₂ quantum dots with L-012, a highly sensitive analogue of luminol. Additionally, the use of L-012 improved the detection limit for hypochlorite to 2 × 10⁻⁶ M. Due to its selectivity in determining hypochlorite in the presence of reactive oxygen species (hydrogen peroxide) under neutral conditions with high sensitivity and with a wide linear range, the proposed approach provides an attractive analytical tool for the analysis of water samples and biological liquids. Full article

Novel photocatalysts were synthesized through the association of carbon quantum dots (CQDs) with commercial (P25) titanium dioxide (TiO₂) by sonication. The resulting TiO₂/CQDs composite was then incorporated into the polyamide 66 (PA66) biopolymer nanofibers using the electrospinning technique, considering a composite nanoparticles-to-polymer ratio of 1:2 in the electrospinning precursor solution. The produced nanofibers presented suitable morphology and were tested for the photocatalytic degradation under simulated solar radiation of 10 mg L⁻¹ of amoxicillin (AMX) and sulfadiazine (SDZ), in phosphate buffer solution (pH 8.06) and river water, using 1.5 g L⁻¹ of photocatalyst. The presence of the photocatalyst increased the removal of AMX in phosphate buffer solution by 30 times, reducing the AMX degradation half-life time from 62 ± 1 h (without catalyst) to 1.98 ± 0.06 h. Moreover, SDZ degradation half-life time in phosphate buffer solution was reduced from 5.4 ± 0.1 h (without catalyst) to 1.87 ± 0.05 h in the presence of the photocatalyst. Furthermore, the PA66/TiO₂/CQDs were also efficient in river water samples and maintained their performance in at least three cycles of SDZ photodegradation in river water. The presented results evidence that the produced photocatalyst can be a promising and sustainable solution for antibiotics’ efficient removal from water. Full article

This study introduces a novel approach to addressing environmental issues by developing fish-scale carbon nanoparticles (FSCNPs) with a wide range of colors from discarded fish scales. The process involves hydrothermally synthesizing raw tamban (Sardinella) fish scales sourced from Universal Canning, Inc. in Zamboanga City, Philippines. The optimization of the synthesis was achieved using the response surface methodology with a Box–Behnken design. The resulting FSCNPs exhibited unique structural and chemical properties akin to carbonized polymer dots, enhancing their versatility. The solid-state fluorescence of these nanoparticles can be modulated by varying their concentration in a polyvinylpyrrolidone matrix, yielding colors such as blue, green, yellow, and red-orange with Commission Internationale de l’Eclairage coordinates of (0.23, 0.38), (0.32, 0.43), (0.37, 0.43), and (0.46, 0.48), respectively. An analysis of the luminescence mechanism highlights cross-linking emissions, aggregation-induced emissions, and non-covalent interactions, which contribute to concentration-dependent fluorescence and tunable emission colors. These optical characteristics suggest that FSCNPs have significant potential for diverse applications, particularly in opto-electronic devices. Full article

A fluorescent probe based on ternary AgFeS₂ quantum dots has been prepared for the design of ternary chalcogenides. The nanoparticles are synthesized with oleylamine as a stabilizer at a low temperature (particle size in the range of 2 to 3 nm) and they exhibit an intense blue emission in aqueous media. As for their internal structure, each nanoparticle’s relative stoichiometric ratio (AgFe_1.01S_1.91) is very close to the theoretical value of 1:1:2. Their magnetic properties have been studied with a vibrating sample magnetometer and they have ferromagnetism between 4 K and 298 K (applied magnetic field ranging between −10,000 and 10,000 Oe). In the presence of iodide ions, the emission at 458 nm derived from AgFeS₂ QDs has been observed to give rise to fluorescence quenching. The detection system is based on a static quenching process and morphological change between iodide ions and AgFeS₂, which has a good linear range from 0 to 37.5 μmol/L, with a limit of detection of 0.99 μM. The nanoprobe responds within 30 s for the efficient detection of iodide. Such functional quantum dots will provide a powerful indicator in environmental and bio-sensing applications. Full article

Foam drainage agents enhance gas production by removing wellbore liquids. However, due to the ultra-high salinity environments of the Hechuan gas field (salinity up to 32.5 × 10⁴ mg/L), no foam drainage agent is suitable for this gas field. To address this challenge, we developed a novel nanocomposite foam drainage system composed of quaternary ammonium and two types of nanoparticles. This work describes the design and synthesis of a quaternary ammonium foam drainage agent and nano-engineered stabilizers. Nonylphenol polyoxyethylene ether sulfosuccinate quaternary ammonium foam drainage agent was synthesized using maleic anhydride, sodium chloroacetate, N,N-dimethylpropylenediamine, etc., as precursors. We employed the Stöber method to create hydrophobic silica nanoparticles. Carbon quantum dots were then prepared and functionalized with dodecylamine. Finally, carbon quantum dots were incorporated into the mesopores of silica nanoparticles to enhance stability. Through optimization, the best performance was achieved with a (quaternary ammonium foam drainage agents)–(carbon quantum dots/silica nanoparticles) ratio of 5:1 and a total dosage of 1.1%. Under harsh conditions (salinity 35 × 10⁴ mg/L, condensate oil 250 cm³/m³, temperature 80 °C), the system exhibited excellent stability with an initial foam height of 160 mm, remaining at 110 mm after 5 min. Additionally, it displayed good liquid-carrying capacity (160 mL), low surface tension (27.91 mN/m), and a long half-life (659 s). These results suggest the effectiveness of nanoparticle-enhanced foam drainage systems in overcoming high-salinity challenges. Previous foam drainage agents typically exhibited a salinity resistance of no more than 25 × 10⁴ mg/L. In contrast, this innovative system demonstrates a superior salinity tolerance of up to 35 × 10⁴ mg/L, addressing a significant gap in available agents for high-salinity gas fields. This paves the way for future development of advanced foam systems for gas well applications with high salinity. Full article

The detection of lipopolysaccharide (LPS) has important value for the monitoring of diseases such as sepsis and the impurity control of drugs. In this work, we prepared guanidinylated carbon dots (GQ-CDs) and used them to adsorb 5-carboxyfluorescein (FAM)-labeled single-stranded DNA (ssDNA) to become GQ-CDs/FAM-DNA, resulting in quenched FAM. The quenching efficiency of the FAM-DNA by GQ-CDs in the GQ-CDs/FAM-DNA system was 91.95%, and this quenching was stable over the long term. Upon the addition of LPS, the quenched FAM-DNA in the GQ-CDs/FAM-DNA system regained fluorescence at 520 nm. The mechanism studies found that the addition of LPS promoted the dissociation of FAM-DNA adsorbed on GQ-CDs, thereby restoring fluorescence. The degree of fluorescence recovery was closely related to the content of LPS. Under optimized conditions, the fluorescence recovery was linearly related to LPS concentrations ranging from 5 to 90 μg/mL, with a detection limit of 0.75 μg/mL. The application of this method to plasma samples and trastuzumab injections demonstrated good spiked recoveries and reproducibility. This platform, based on GQ-CDs for the adsorption and quenching of FAM-DNA, enables the detection of LPS through relatively simple mixing operations, showing excellent competitiveness for the determination of actual samples under various conditions. Full article

Fluorescent materials for sensing have gained attention for the visual detection of different substances as metals and pesticides for environmental monitoring. This work presents fluorescent nanocomposites in solution, film, and paper obtained without capping and stabilizing agents, coming from quantum dots of cadmium sulfide (CdS QDs) and anionic–cationic polymer matrices. Fluorescent films were formed by casting and fluorescent paper by impregnation from the solutions. The optical properties of CdS QDs in solution showed absorption between 418 and 430 nm and a maximum emission at 460 nm. TEM analysis evidenced particle size between 3 and 6 nm and diffraction patterns characteristic of CdS nanocrystals. Infrared spectra evidenced changes in the wavenumber in the fluorescent films. The band gap values (2.95–2.82 eV) suggested an application for visible transmitting film. Fluorescent solutions by UV-vis and fluorescence evidenced a chemical interaction with glyphosate standard between 1 and 100 µg/mL concentrations. The analysis of red, green, and blue color codes (RGB) evidenced a color response of the fluorescent paper at 10 and 100 µg/mL, but the fluorescent films did not show change. Nanocomposites of chitosan and pectin, in solution and on paper, exhibited a behavior “turn-on” sensor, while carboxymethylcellulose had a “turn-off” sensor. This methodology presents three fluorescent materials with potential applications in visual sensing. Full article

A large number of the thin-film organic structures (polyimides, 2-cyclooctylarnino-5-nitropyridine, N-(4-nitrophenyl)-(L)-prolinol, 2-(n-Prolinol)-5-nitropyridine) sensitized with the different types of the nano-objects (fullerenes, carbon nanotubes, quantum dots, shungites, reduced graphene oxides) are presented, which are studied using the holographic technique under the Raman–Nath diffraction conditions. Pulsed laser irradiation testing of these materials predicts a dramatic increase of the laser-induced refractive index, which is in several orders of the magnitude greater compared to pure materials. The estimated nonlinear refraction coefficients and the cubic nonlinearities for the materials studied are close to or larger than those known for volumetric inorganic crystals. The role of the intermolecular charge transfer complex formation is considered as the essential in the refractivity increase in nano-objects-doped organics. As a new idea, the shift of charge from the intramolecular donor fragment to the intermolecular acceptors can be proposed as the development of Janus particles. The energy losses via diffraction are considered as an additional mechanism to explain the nonlinear attenuation of the laser beam. Full article

In this paper, we developed a paper-based fluorescent sensor using functional composite materials composed of graphene quantum dots (GQDs) coated with molecularly imprinted polymers (MIPs) for the selective detection of tetracycline (TC) in water. GQDs, as eco-friendly fluorophores, were chemically grafted onto the surface of paper fibers. MIPs, serving as the recognition element, were then wrapped around the GQDs via precipitation polymerization using 3-aminopropyltriethoxysilane (APTES) as the functional monomer. Optimal parameters such as quantum dot concentration, grafting time, and elution time were examined to assess the sensor’s detection performance. The results revealed that the sensor exhibited a linear response to TC concentrations in the range of 1 to 40 µmol/L, with a limit of detection (LOD) of 0.87 µmol/L. When applied to spiked detection in actual water samples, recoveries ranged from 103.3% to 109.4%. Overall, this paper-based fluorescent sensor (MIPs@GQDs@PAD) shows great potential for portable, multi-channel, and rapid detection of TC in water samples in the future. Full article

Grapes are susceptible to mold and decay during postharvest storage, and developing new technologies to extend their storage period has important application value. Photodynamic technology (PDT) in concurrence with carbon dots (CDs) proposes an innovative and eco-friendly preservation strategy. We examined the effects of carbon dots combined with photodynamic treatment on postharvest senescence and antioxidant system of table grape. The compounding of photodynamic technology with a 0.06 g L⁻¹ CDs solution could possibly extend the postharvest storage period of grape berries. Through this strategy, we achieved a decreased rate of fruit rotting and weight loss alongside the delayed deterioration of fruit firmness, soluble solids, and titratable acid. As paired with photodynamic technology, CDs considerably decreased the postharvest storage loss of phenols, flavonoids, and reducing sugars as compared to the control group. Concurrently, it remarkably postponed the build-up of hydrogen peroxide (H₂O₂), superoxide anion (O₂^∙−), and malondialdehyde (MDA); elevated the levels of reduced ascorbic acid (AsA) and reduced glutathione (GSH); lowered the levels of dehydroascorbic acid (DHA) and oxidized glutathione (GSSG); raised the ratios of AsA/DHA and GSSH/GSSG; encouraged the activities of superoxide dismutase (SOD) and phenylalanine ammonia-lyase (PAL); and inhibited the activities of polyphenol oxidase (PPO) and lipoxygenase (LOX). Furthermore, it enhanced the iron reduction antioxidant capacity (FRAP) and DPPH radical scavenging capacity of grape berries. CDs combined with photodynamic treatment could efficiently lessen postharvest senescence and decay of grape berry while extending the storage time. Full article