KR101765557B1 - Bioresorbable Electronic Stent - Google Patents

Abstract

The present invention relates to a bioabsorbable electronic stent. More particularly, the present invention relates to a bioabsorbable nonvolatile resistance memory element; A bioabsorbable flow rate sensor; A bioabsorbable temperature sensor; A biodegradable first polymer layer containing cerium oxide nanoparticles; And a biodegradable second polymer containing a drug release nanostructure comprising a core made of metal nanoparticles that generates heat by irradiation of near infrared rays to provide power for drug release and a mesoporous silica shell in which a drug is loaded and released, 0.0 > bioadhesive < / RTI > electronic stent.

Description

Bioresorbable Electronic Stent < RTI ID = 0.0 >

The present invention relates to a bioabsorbable electronic stent. More particularly, the present invention relates to a bioabsorbable nonvolatile resistance memory element; A bioabsorbable flow rate sensor; A bioabsorbable temperature sensor; A biodegradable first polymer layer containing cerium oxide nanoparticles; And a biodegradable second polymer containing a drug release nanostructure comprising a core made of metal nanoparticles that generates heat by irradiation of near infrared rays to provide power for drug release and a mesoporous silica shell in which a drug is loaded and released, 0.0 > bioadhesive < / RTI > electronic stent.

Balloon angioplasty and stent placement procedures help patient care across a wide range of cardiovascular, neurovascular, and peripheral vascular diseases.

Approximately six million patients each year receive percutaneous coronary intervention (PCI) for the treatment of arterial occlusion and endothelial injury. Although PCI using bare metal restores blood flow, there is an important limitation that neointimal hyperplasia and smooth muscle cells can accumulate around the stent. This limitation is believed to occur due to the complex interactions of the turbulent blood flow and inflammatory reaction around the stent.

Stent restenosis (ISR), which includes bioresorbable stent and drug-eluting stent, each of which is physically absent or delivers drugs to overcome the drawbacks of metal stents, ) Have been reported.

Although these conventional endovascular implants minimize health risks and are very useful, there is no onboard sensor, data storage, and therapeutic actuation, so that the hemodynamics associated with local delivery of advanced therapeutic agents And diagnostic feedback on the active control state.

A bioabsorbable electronic stent that complexly senses blood flow and temperature through an integrated electronic device associated with a data storage module represents a fundamentally new onboard functional or inactive bioabsorbable implant.

A high performance, flexible, bioabsorbable electronic device provides a unique solution for integrating active electronics onto an expandable, bioabsorbable stent. In addition, advanced therapeutics through functionalized nanoparticles enable further enhancement of PCI through controlled drug release and inhibition of prolonged inflammation.

Inorganic nanoparticles have been studied as therapeutic platforms due to their high surface-to-volume ratio, the elimination of reactive oxygen species (ROS), and their photoactivating properties.

The present inventors have found that bioabsorbable / bioerodible nanomaterial designs and their use in conjunction with nanomembrane-based flexible flow / temperature sensors and memory storage devices, anti-inflammatory nanoparticles, and drug- And a bioresorbable electronic stent (BES) with a nanosphere.

It is an object of the present invention to provide a bioabsorbable nonvolatile resistance memory element; A bioabsorbable flow rate sensor; A bioabsorbable temperature sensor; A biodegradable first polymer layer containing cerium oxide nanoparticles; And a biodegradable second polymer containing a drug release nanostructure comprising a core made of metal nanoparticles that generates heat by irradiation of near infrared rays to provide power for drug release and a mesoporous silica shell in which a drug is loaded and released, Wherein the drug delivery layer comprises a drug delivery layer comprised of at least one layer of a bioabsorbable polymer.

An object of the present invention described above is to provide a bioabsorbable nonvolatile resistance memory element; A bioabsorbable flow rate sensor; A bioabsorbable temperature sensor; A biodegradable first polymer layer containing cerium oxide nanoparticles; And a biodegradable second polymer containing a drug release nanostructure comprising a core made of metal nanoparticles that generates heat by irradiation of near infrared rays to provide power for drug release and a mesoporous silica shell in which a drug is loaded and released, Absorbent < / RTI > electronic stent, comprising a drug-delivery layer consisting of a layer of biocompatible polymeric material.

In one embodiment of the present invention, a bioabsorbable flow rate sensor is formed adjacent to the inner surface of the bioabsorbable electronic stent, and a first drug delivery layer may be formed adjacent to the bioabsorbable flow rate sensor. In addition, a bioabsorbable nonvolatile resistance memory element is formed adjacent to the outer surface of the bioabsorbable electronic stent, a biosorbent temperature sensor is formed adjacent to the resistance memory element, and a second drug delivery layer And a biodegradable first polymer layer containing cerium oxide nanoparticles adjacent to the second drug-transporting layer may be formed.

The bioabsorbable nonvolatile resistance memory element included in the bioabsorbable electronic stent of the present invention includes biocompatible electrodes that can be hydrolyzed into a bioabsorbable material and a resistor capable of being hydrolyzed with the bioabsorbable material located between the electrode layers Layer.

In the bioabsorbable nonvolatile resistive element, the electrode may be magnesium or zinc, and the thickness of the electrode layer is preferably 10 nm to 500 nm.

In one embodiment of the present invention, the electrode may be made of magnesium. In this case, the magnesium is decomposed by the following hydrolysis reaction and absorbed in vivo.

Mg + 2H ₂ O - > Mg (OH) ₂ + H ₂

In another embodiment of the present invention, the electrode may be made of zinc. In this case, the zinc is decomposed by the following hydrolysis reaction and absorbed in vivo.

Zn + 2H ₂ O? Zn (OH) ₂ + H ₂

Further, in the above-described bioabsorbable nonvolatile resistive element, the resistance layer may be selected from magnesium oxide, zinc oxide or molybdenum oxide, and the thickness of the resistance layer is preferably 5 nm to 500 nm.

In one embodiment of the present invention, the resistive layer can be made of magnesium oxide, and the magnesium oxide becomes a material which can be absorbed in vivo by the following hydrolysis reaction.

_{MgO + H 2 O → Mg (} OH) 2

The bioabsorbable flow rate sensor or the bioabsorbable temperature sensor included in the bioabsorbable electronic stent of the present invention includes biocompatible metal oxide layers that can be hydrolyzed into a bioabsorbable material and biocompatible metal oxide layers that are disposed between the metal oxide layers To < RTI ID = 0.0 > a < / RTI >

The metal oxide used for the bioabsorbable flow rate sensor or the bioabsorbable temperature sensor may be selected from magnesium oxide, zinc oxide or molybdenum oxide. Moreover, the thickness of the metal oxide layer may be between 10 nm and 1 mm.

In one embodiment of the present invention, the metal oxide layer can be made of magnesium oxide, and the magnesium oxide becomes a material which can be absorbed in vivo by the following hydrolysis reaction.

_{MgO + H 2 O → Mg (} OH) 2

The metal layer used for the bioabsorbable flux sensor or the bioabsorbable temperature sensor may be magnesium (Mg), zinc (Zn), or iron (Fe). The thickness of the metal layer may be between 10 nm and 1 mm.

In one embodiment of the present invention, the electrode can be made of magnesium, zinc or iron. In this case, the magnesium is decomposed by the following hydrolysis reaction and absorbed in vivo.

Mg + 2H ₂ O - > Mg (OH) ₂ + H ₂

In the biodegradable first polymer layer containing the cerium oxide nanoparticles, the size of the ceria nanoparticles may be 1 nm to 100 nm. The ceria nanoparticles can remove reactive oxygen species (ROS) in the living body.

The first polymer material may be a synthetic polymer such as biodegradable polyesters such as polylactic acid (PLA), polyglycolic acid (PGA), polyglycerol sebacate (PGS) and copolymers thereof, or synthetic polymers such as silk, chitosan Chitosan, starch, hyaluronic acid, gelatin, cellulose, and the like. The thickness of the polymer material layer may be 100 nm to 1 mm.

In the drug delivery layer, the metal nanoparticles may be gold or silver. The size of the metal nanoparticles may be 3 nm to 100 nm.

In the drug delivery layer, the diameter of the mesoporous silica shell may be 50 nm to 150 nm.

In the drug delivery layer, the drug loaded on the nanostructure may be a smooth muscle cell proliferation inhibitor. In particular, the drug loaded on the nanostructure may be rapamycin or paclitaxel.

In addition, in the drug delivery layer, the pore diameter of the silica shell may be 2 nm to 6 nm.

In the drug delivery layer, the bioabsorbable polymer material may be a biodegradable polyester such as polylactic acid (PLA), polyglycolic acid (PGA), polyglycerol sebacate (PGS), or a synthetic polymer such as a copolymer thereof It may be a natural polymer such as silk, chitosan, starch, hyaluronic acid, gelatin, and cellulose. The thickness of the polymer material layer may be 100 nm to 1 mm.

The bioabsorbable electronic stent of the present invention can be used for advanced treatment of drug release based on catalytic ROS removal and hyperthermia. First, ceria nanoparticles are used to remove ROS produced in reperfusion during PCI procedures and to reduce inflammation causing intra-stent thrombosis. Second, a drug-filled gold nanorod core / mesoporous silica nanoparticle shell (AuNR @ MSN) is activated photothermally by a near-infrared (NIR) laser and feedback from an embedded temperature sensor . Hyperthermia not only controls localized drug delivery but also provides thermal therapy. These sensors and actuators provide mechanical, photothermal, diagnostic and therapeutic functionality to the bioabsorbable stent substrate.

1A is a schematic view (left side), a top view (upper right), and layer information (lower right) of a bioabsorbable electronic stent (BES) of the present invention, FIG. 1C is a photograph of the BES taken in the left carotid artery (right side) and the posterior (right side) of the Poongsan catheter. 1D is a photograph of a BES placed in dogs of the common carotid artery and FIG. 1E is a volumetric CT photograph of a BES placed in dogs of the common carotid artery.
FIG. 2A shows a developed view (left side) of the stent of the present invention and the hydrolysis reaction thereof (right side), and FIG. 2B shows the results of 8 weeks old BALB / c mice (n = 3, 5 mg Au / kg (ionic concentration in blood plasma time) of ceria nanoparticles, AuNR @ MSN, and AuNR injected into a mouse weight or 2.5 mg Ce / kg mouse weight, and FIG. 2c shows the results of 8-week old BALB / c mice Barium distribution profile of ceria nanoparticles, AuNR @ MSN, and AuNR, injected into n = 6, 0.00625 mg Ce / mouse or 0.125 mg Au / mouse for a particle group.
FIG. 3A is a current-voltage (IV) characteristic of the bipolar resistance memory of the Mg / MgO / Mg structure, FIG. 3B is a TEM image (transmission electron microscope) photograph of the Mg / MgO / Mg memory cell, FIG. 3E is retention characteristics of the memory, and FIG. 3E is a graph of cumulative probability as a function of the set / reset resistance. FIG. 3f is the endurance characteristic of the memory measured at +0.2 V, FIG. 3g is the finite element modeling (FEM) result of the strain distribution in the active layer (MgO) of the memory, FIG. 3h is the in- Fig. 3i is a plot of the percent resistance change versus flow rate of the flow sensor at three different currents of the flow sensor, and Fig. 3j is a plot of BES within the aortic flow velocity sensor (measured at a constant current of 50 mA) Percent Resistance It is plotted (upper part) of the screen (this is the measured flow rate is stored in the memory cell through the multi-level cell (multi-level cell (MLC)) operation after it is converted to a digital signal).
4A is a TEM image of a ceria nanoparticle (the inset is an enlarged photograph by a high-resolution TEM), Fig. 4B is a schematic view of a mechanism of removing ROS by ceria nanoparticles, Fig. 4C is a schematic view of ceria Fig. 4D is a plot of the ROS removal activity of the nanoparticle-containing PLA film. Fig. 4D is a plot of the ROS removal activity of the nanoparticle-containing PLA film in a human umbilical vein endothelial cell (HUVEC) under 50 μM ROS 4f is the cell survival rate under 50 [mu] M ROS of HUVEC with various ceria nanoparticle concentrations and Fig. 4f is the fluorescence spectra of 50 [mu] M (left) FIG. 4g is the fluorescence image of mouse myocardial cell (HL-1) under ROS, FIG. 4g is the cell viability of HL-1 by various ceria nanoparticle concentrations under 50 μM ROS, Immunolabeling photographs of the MAC387 (macrophages) of the medium and the subcutaneous layer (left), the subcutaneous layer and the inner membrane (right) near the graft site containing the noparticles, and Fig. 4i is an immunolabeling image of the celiac nano In vivo immunolabeling photographs of the MAC387 (macrophages) of the medium and the subcutaneous layer (left), the subcutaneous layer and the inner membrane (right) near the graft site of the non-particle-containing stent.
FIG. 5A is a conceptual diagram showing localized and controlled drug release by the hyperthermia effect of AuNR @ MSN associated with near infrared (NIR) laser irradiation, FIG. 5B is a conceptual view showing AuNR (core) containing an anti-stenotic drug (rapamycin) (TEM) photograph of a mesoporous silica (shell), FIG. 5C shows a simulated drug release experiment using a fluorene dye loaded in AuNR @ MSN under near-infrared irradiation, and FIG. 5D shows a simulated drug release experiment in vivo FIG. 5E is a fluorescence image showing the Nile red dye diffused from the stent into the inside of the total carotid artery. FIG. 5E is a fluorescence image showing the presence of AuNR @ MSN under intermittent near-infrared irradiation (left side, experimental group) FIG. 5f shows the results of thermal finite element modeling for temperature distribution near the stent / endocardial interface at a blood flow rate of 2 mm / s, FIG. The temperature distribution of the vascular tissue near the heated stent (endocardium and subdermal layer) was measured at the tissue depth (0 mm / s) with or without blood flow (2 mm / s) 5h is a HUVEC photograph of a PLA film containing AuNR @ MSN (dotted boxes are exposed to a near-infrared laser at 17 mW output in vitro). The green and red regions are the living and dead cells, respectively, (Photo-bleaching of the green dye is observed), Figure 5i is a photograph of HUVEC under a near-infrared laser with increased power (29 mW) (killing cells (red) due to the hyperthermia effect) , Fig. 5J is a photograph of HUVEC under a near-infrared laser with a power of 40 mW (all cells exposed to near infrared are killed due to the hyperthermia effect of AuNR @ MSN), and Fig. 5k is cell survival data measured from Figs. 4h to 4j .
FIG. 6A is an optical diagram of a stent strut being fabricated from a Mg alloy ingot, FIG. 6B is an exemplary diagram of a process for fabricating a bioabsorbable RRAM on a stent, FIG. 6C is a cross- FIG. 6D is an enlarged view of the bioabsorbable electronic stent (BES) fabricated. FIG.
Figure 7a shows the percent resistance change of the Mg gypsum line (100 nm) in phosphate buffered saline (PBS) using different encapsulation materials (blue: no encapsulation, red: MgO 300 nm, black: MgO 300 nm / PLA 120 nm) As a function of time, and Figure 7b is an optical micrograph of a twisted shape Mg (50 nm) metal interconnect in PBS every 10 minutes.
Figure 8 shows that the excess of bioactive nanoparticles are injected through the tail vein into an auxiliary lymph node (Figure 8a), brachial lymph node (Figure 8b), inguinal lymph node (Figure 8c), heart (H & E) staining histology for the kidney (FIG. 8D) and kidney (FIG. 8E).
Figure 9 shows that hematoxylin and eosin (H & E) for the liver (Figure 9a), lung (Figure 9b), pancreas (Figure 9c) ) Staining histology.
FIG. 10A shows the elongated interconnection at various strains ranging from 0% to 100%, FIG. 10B shows the currents of the RRAM performed in both the initial (red) and strained (blue) conditions on the balloon catheter - Show voltage characteristics.
11A is a TEM image for AuNR @ MSN with small pore size (left) and large pore size (right), and FIG. 11B is TEM image for adsorbed and desorbed isotherm measurements at 77 K versus adsorbed N ₂ volume versus relative N ₂ (The inset shows the pore distribution of AuNR @ MSN using the Barrett-Joyner-Halenda method), and FIG. 11C is the normalized adsorption spectrum of AuNR @ MSN.
12A is a diagram showing a region (18% of the total area of the temperature sensor) exposed to a near-infrared laser spot, FIG. 12B is a diagram showing a plot (percentage resistance change versus temperature change, 12C is a photograph of a near infrared ray laser setting, and FIG. 12D is a graph showing a percentage resistance (blue) to a percent resistance change (blue) under a near-infrared laser irradiation of 29 mW output for 80 seconds (Red) and the estimated temperature as a function of time, and Figure 12E plots the temperature change as a function of the near-infrared laser irradiation time under various near-infrared laser power in the range of 17 mW to 160 mW.

Hereinafter, the present invention will be described in more detail with reference to the following examples or drawings. It is to be understood, however, that the following description of the embodiments or drawings is intended to illustrate specific embodiments of the invention and is not intended to be exhaustive or to limit the scope of the invention to the precise forms disclosed.

Example  One. Celia  Synthesis of nanoparticles

Cerium acetate (0.4 g, 98%, Sigma Aldrich, USA) and oleylamine (70%, 3.2 g, Acros, USA) were added to 15 mL of xylene (98.5%, Sigma Aldrich, USA). The solution was stirred at room temperature for 2 hours and then heated to 90 [deg.] C (2 [deg.] C / min). At 90 DEG C, 1 mL of deionized water was added while vigorously stirring the solution. The solution then turned off-white, which means that the reaction was initiated. The mixture was stored at 90 占 폚 for 3 hours and then turned into a light-yellow colloidal solution, which was cooled to room temperature. Acetone was added to precipitate the ceria nanoparticles, and the ceria nanoparticles were dispersed in chloroform. To prepare bioactive ceria nanoparticles, organic-dispersed ceria nanoparticles were coated with PEG-phospholipid. 50 mg of mPEG-2000 PE (Avanti, USA) dissolved in 5 mL of CHCl ₃ was added to 5 mL of ceria nanoparticle solution (10 mg / mL in CHCl ₃ ). The solvent was evaporated by rotary evaporator and the product was aged in a vacuum oven at < RTI ID = 0.0 > 80 C < / RTI > for an additional hour. Then, 5 mL of solvent (deionized water or CHCl ₃ ) was added to the product and the excess PEG-phospholipid was removed by ultracentrifugation.

Example  2. Gold Of the gold nanorod  synthesis

(CTAB, 99 +%, Acros, USA) was added to 7.5 mL of 100 mM cetyltrimethylammonium bromide solution (CTAB, 99%, Acros, USA) in an aqueous solution of 0.25 mL of 10 mM HAuCl ₄ .3H ₂ O (gold seed particle). It was added to 10 mM NaBH ₄ solution was cooled in 0.6 mL of ice, and was prepared (pale-brown) of the seed cloudy brown solution was stirred for 2 hours. A gold nanorod (AuNR) growth solution was prepared by mixing 160 mL of 100 mM CTAB, 6.8 mL of 10 mM HAuCl ₄ .3H ₂ O and 1 mL of 10 mM AgNO ₃ (99%, Sigma Aldrich, USA). Then, 1.08 mL of 100 mM L-ascorbic acid (99%, Sigma Aldrich, USA) was added, thereby changing the color of the solution from yellowish brown to colorless. To initiate the growth of nanorods, 1.68 mL of seed solution was added to the growth solution and allowed to stand for 3 hours. To prepare a pegylated gold nano rod (PEGylated AuNR) for in vivo experiments, AuNR was centrifuged twice and dispersed in 10 mL of water. Then, 100 mg of mPEG-SH 5000 (Sulfhydryl terminated, Sunbio, Korea) was added and stirred for 12 hours. Excess mPEG-SH was removed by centrifugation, and AuNR was filtered and redispersed in water.

Example  3. Gold Nanorod  core/ Siege  Synthesis of silica nanoparticles (AuNR @ MSN)

The AuNR solution prepared in Example 2 was centrifuged, washed and redispersed in 40 mL of water. CATB (0.08 g, > 99%, Acros, USA) and 0.24 mL NaOH solution (2 M) were added to the solution. The solution was then heated to 70 ° C. and then treated with 1.2 mL of mesitylene (99%, Sigma Aldrich, USA), 0.4 mL of tetraethylorthosilicate (TEOS, 98%, Acros, USA) Of ethyl acetate were added successively. After stirring for 3 hours, the obtained AuNR @ MSN was collected by centrifugation and washed with a large amount of water and ethanol. The pore-generating template, CATB, was then removed by stirring in an acidic ethanol solution. For surface functionalization, AuNR @ MSN was redispersed in ethanol. 0.1 mL of 3-aminopropyltriethoxysilane (APTES, 99%, Sigma Aldrich, USA) was added and the solution was refluxed for 3 hours. AuNR @ MSN (AuNR @ MSN-NH ₂ ) functionalized with amine groups was centrifuged and redispersed in 5 mL of anhydrous ethanol. To introduce PEG onto the AuNR @ MSN surface, 100 mg of mPEG-SG 5000 (Succinimidyl glutarate terminated, Sunbio, Korea) was added and stirred for 12 hours. After the reaction, it was removed by the excess of mPEG-SG centrifugation, followed by dispersion of the product in CHCl _3. The final concentration of gold measured by ICP-AES was 2.878 mg / mL.

Example  4. Mg  alloy Stent  On Mg / MgO / Mg  Manufacture of memory

To fabricate the Mg alloy stent, the ZM21 Mg alloy ingot was laser-cut and polished first. AZ4620 photoresist (Clariant, USA) was spin coated on both sides of the ZM21 Mg alloy substrate (~ 200 μm) at 3000 rpm (30 seconds). The Mg alloy substrate was then patterned using a wet etching process using photolithography and an Mg etchant (70% ethylene glycol, 20% deionized water, 10% nitric acid). After the etching process, the Mg alloy mesh was immersed in boiling acetone to remove the AZ4620 photoresist. Thereafter, an insulated MgO layer (~50 nm) was deposited on the stent by an electron beam evaporation method. Subsequently, the lower electrode (Mg, 60 nm) was formed by thermal evaporation of Mg. A switching layer (MgO, 12 nm) was deposited by a sputtering process (base pressure of 5 × 10 ^-6 Torr, Ar 20 sccm, 5 mTorr, 150 W RF power). Next, an upper electrode (Mg, ~ 60 nm) was deposited on the MgO film through another thermal evaporation process step. Another MgO encapsulation layer (~ 80 nm) was added to the upper surface of the Mg / MgO / Mg (RRAM) structure using the electron beam evaporation method. Finally, a full-RRAM above the stent, dip-coating (dip-coating) PLA (M w ~ 160,000 , which contains a (3 wt% in chloroform) of ceria nanoparticles and AuNR @ MSN through technology, M _w / M _n ~ 1.5, Sigma Aldrich, USA).

Example  5. Mg  alloy Stent  Fabrication of temperature / flow sensors on

The Mg temperature and flow sensor consists of an adhesion layer, a long filament Mg resistor, and an outer encapsulation layer (MgO and PLA). First, the adhesion layer (~ 60 nm thick ZnO) was sputtered on a PLA film of about 15 μm thickness (base pressure of 5 × 10 ^-6 Torr, Ar 20 sccm, 5 mTorr, 150 W RF power). The metal wiring (Mg, ~ 100 nm) was thermally evaporated through a shadow mask. For encapsulation, an electron beam evaporation method was used to grow about 400 nm thick MgO. An additional two PLA layers (~ 15 μm) were laminated on top by a solvent-vapor-annealing process. Finally, the sensor film was transferred and printed on the stent by a solvent-vapor-annealing process.

Example  6. In vitro ROS  Removal experiment

Mouse heart muscle cells (HL-1) were cultured in DMEM supplemented with 10% fetal bovine serum (Wisent, Canada), 1% penicillin / streptomycin (Gibco, USA), 0.1 mM norepinephrine (Sigma Aldrich, (Claycomb medium; Sigma Aldrich, USA) supplemented with L-glutamine (Gibco, USA). Separately, HUVECs were incubated in EGMTM-2 BulletKit ^™ (Lonza, Switzerland) at 37 ° C under 5% CO ₂ and 95% air. For in vitro ROS removal experiments, HL-1 cells and HUVEC were placed in 24-well plates and incubated again for 3 days. After removal of the cell medium, a PLA film (1 cm x 1 cm, ~ 0.16 g) containing ceria nanoparticles was placed in the well plate. Reactive oxygen species (50 μM H ₂ O ₂ , Sigma Aldrich, USA) was added to the well plates and stored for 5, 10, 15, and 30 minutes to observe the oxidative stress effect. Cells were washed with Dulbecco's phosphate buffered saline (DPBS) and cell viability was measured using the Live / Dead Cell viability / cytotoxicity kit (Invitrogen, USA). Fluorescence images were obtained using a fluorescence microscope (Nikon Eclipse Ti, Japan) and quantitative estimates of living and dead cells were obtained by Image-Pro plus software (MediaCybernetics, USA) kit.

Example  7. In vitro  Thermal Therapy Experiment

To monitor cellular damage caused by hyperthermia, photothermal thermal therapy was performed on HUVECs cultured in 24-well plates with AuNR @ MSN-PLA film (5 mm x 5 mm) for 3 days. Cell viability / cytotoxicity kit solutions were added to the media to visualize live and dead cells. An 80 nm-pulsed laser (Mai Tai eHP deepsee, Spectra-Physics, USA) was irradiated at different power for 10 minutes for the photothermal thermal treatment. After near-infrared irradiation, photographs of cells were obtained using a confocal microscope (LSM-780, Carl Zeiss, Germany).

result

Figures 1a and 1b illustrate the use of ceria nanoparticles (catalytic ROS removal), AuNR @ MSN (thermal therapy), drugs (e.g., rapamycin), flow rate / temperature sensors (physiological signal detection) (BES) including a magnesium alloy stent having an integrated bioabsorbable stent. These components consist of bioabsorbable and bio-inert materials (see FIG. 2). The manufacturing method, materials, geometrical information and photographs for the BES are shown in FIG. Figure 1B shows the BES (contraction state) ready to be mounted on the gross carotid arteries by access through the artery. Bottom inset is an enlargement of BES coated with nanoscale remedy, showing RRAM and temperature sensor. Figure 1c shows an X-ray picture of the contraction (left) and inflated (right) balloon catheters used for mounting the BES. The expanded BES mechanically supports the artery. An optical photograph (FIG. 1d) and a volume-rendered CT (computed tomography) photograph (FIG. 1e) show an expanded BES mounted within the target artery.

Figure 2a shows an example of bioabsorbable and bioactive inactive stacks of active electronic devices and therapeutic nanoparticles on a Mg-Zn-Mn alloy (ZM21; Mg 97%, Zn 2%, Mn 1%) struts to be. These electronic components were composed of bioabsorbable (Mg, MgO, Zn, ZnO and polylactic acid (PLA)) and biologically inert (Mn) materials. Therapeutic nanoparticles (ceria nanoparticles and AuNR @ MSN) and drug were included in the PLA layer of a stent coated with a dissolution rate controllable oxide / polymer (Fig. 7A). All nanoparticles used were either bioabsorbable (SiO ₂ ) or bioactive (CeO ₂ , Au). The rate of degradation of the active agent (by immersion in body fluids) is illustrated in Figure 7b, which can be achieved by adjusting the geometry and materials of the coating oxides (e.g., MgO) and polymers (e.g., PLA, Lt; / RTI >

In addition to bioabsorbability, a key criterion for effective clinical treatment is the suitability of in vivo models and bioactive nanomaterials. Excess (> 1,000-fold) biologically inactive nanoparticles were injected through the tail vein of normal mice to evaluate the effect on internal organs. In vivo pharmacokinetic studies in mice, ceria nanoparticles, AuNR @ MSN and gold nanoparticles have been shown to have a half-life similar to that reported in the past (Fig. 2b). These results show that ceria nanoparticles, AuNR @ MSN and gold nanoparticles are very stable in the bloodstream, minimizing unwanted interactions with proteins and minimizing plaque formation that shortens half-life.

Studies on biodistribution have shown that bioactive inactive nanoparticles have accumulated in the reticuloendothelial system, such as the kidneys, liver, and lymph nodes, rather than the lungs and other organs, as is commonly observed (Figure 2c). Histological analysis (Figures 8 and 9) shows the biocompatibility of the nanoparticles. These results show that the effect of the bioactive nanoparticles on the in vivo system is minimal.

Figure 3 shows the sensing and data storage results of the active electronics from the BES. The bipolar IV curve for the bioabsorbable Mg / MgO / Mg nanomembrane resistance memory device shows how the device switches bidirectionally between the low resistance state (LRS) and the high resistance state (HRS) 3a). The resistive switching was done by applying a positive voltage (reset of 0.7 V) or a negative voltage (a set of -0.8 V). Low-power operation of the memory was enabled by a low reset and set voltage. The inset of FIG. 3A shows the switching order. FIG. 3B shows a transmission electron microscope (TEM) photograph of the memory module, showing in detail the interface to the MgO nanomembrane switch layer (~ 12 nm) and the Mg electrode. The current values independent of the area of the LRS and HRS suggest that the conduction mechanism is by filamentary connection (FIG. 3C). FIG. 3D shows uniform resistance switching in the RRAM array, where both HRS and LRS are stable. The retention properties of these devices can be extrapolated to several years by a switching cycle (Fig. 3F) in excess of 1,000 cycles (Fig. 3E). The mechanical robustness during the expansion of the BES is confirmed using finite element modeling (FEM) analysis. We assume that the strain (Figure 2g) of the switching layer (MgO nanomembrane) of the BES is smaller than the fracture strain of MgO (~ 8%). Nanometer-thick active layers and serpentine designs (Figure 10a) included in the BES minimize the effects of induced strain on the devices and enable stable IV characteristics under strain. (Fig. 10B).

A bioabsorbable RRAM was combined with the sensor module on the BES to store sensing data. Figure 3h shows an endovascular flow / perfusion model in vitro. Three aorta (Fig. 3h) were excised and the BES was inserted into the path of the simulated blood flow. The fluid velocity sensor of the stent is activated by measuring the resistance change, and then correlates with the change in fluid velocity (Fig. 3i). The RRAM module stores these flow rate data based on a four-level data group corresponding to the flow rate change. These rate changes were saved via MLC operation (Figure 3j). Each fluid velocity was stored in different cells of the memory in real time using Lab-view software. Although the connection of the device is wired, the power and stored data can be wirelessly transmitted by integrating the wireless devices.

To deliver the therapeutic agent, ceria nanoparticles (Fig. 4A and its insert) were included in the outermost encapsulation layer of the BES (left side of Figs. 1A and 4B). Typically, ROS near the graft site promotes endothelial cell apoptosis and ROS-induced inflammatory response, which is one of the main reasons for restenosis. In addition, ROS results in the death of cardiac muscle cells. The oxygen vacancy on the surface of the ceria nanoparticles allows ROS to bind to ceria nanoparticles. Continuous catalytic removal of intravascular ROS is possible by a self-regenerating acidic redox cycle between Ce ^{3 +} and Ce ^{4 +} oxidation states (Fig. 4b right), inhibiting ROS-induced inflammation. Superoxide and hydrogen peroxide were used to simulate increased ROS in cardiovascular system during angioplasty. The ceria nanoparticles encapsulated in the PLA film showed ROS removal activity in a dose-dependent manner (Figure 4c).

In vitro antioxidative effects of ceria nanoparticles were evaluated by exposing human umbilical vein endothelial cells (HUVEC) to oxidative stress (Fig. 4d). When the medium containing ROS was added to the HUVEC, the cell viability decreased sharply (in the absence of ceria nanoparticles) (Fig. 4D left curve and Fig. 4e black curve). In contrast, the addition of ceria nanoparticles encapsulated in a PLA film improves cell viability under oxidative stress, which means that endothelial cells are protected from ROS by ceria nanoparticles. Exposure of the cardiac cell line, HL-1, with ceria nanoparticles decreased oxidative stress, as in the case of HUVEC. The protective effect of ceria nanoparticles in animal models was investigated by evaluating in vivo anti-inflammatory properties. Immunohistochemical analysis after transplantation of BES into the common carotid arteries showed that the presence of ceria nanoparticles inhibited the inflammatory reaction and macrophage migration, whereas in the absence of ceria nanoparticles, Microphage recruitment was observed (Fig. 4I).

In addition to protection against ROS and inflammation, multifunctional therapeutic nanoparticles that respond to external optical stimuli are also included in the BES to enable controlled drug release and photothermal treatment (FIG. 5A). For this type of BES actuation, near infrared-reactive gold nanoparticle cores (about 20 nm long and about 10 nm thick) and drug-fillable mesoporous silica shells (AuNR @ MSN, about 100 nm diameter) And synthesized (FIG. 5B). The larger surface area-to-volume ratio of AuNR @ MSN allows loading of larger drugs (Rapamycin, LC Laboratories), which can help suppress SMC proliferation and restenosis. To make the molecules sufficiently adsorb large drugs, the size of the mesopores was increased by adding a swelling agent (mesitylene, Aldrich, USA) (FIG. 11A). N ₂ adsorption / desorption isotherm analysis shows that AuNR @ MSN has well-developed mesopores. The corresponding Barrett-Joyner-Halenda (BJH) pore size distribution shows an effective pore diameter of about 3.9 nm (FIG. 11B). The UV-Vis adsorption spectrum shows that AuNR @ MSN has an adsorption peak at about 761 nm (FIG. 11C). AuNR @ MSN can be used for minimal or noninvasive photothermal operation of AuNR @ MSN since it reacts to a near-infrared laser (about 800 nm) with a high penetration depth to the soft tissue. Figure 5c highlights in vitro experiments on drug release from AuNR @ MSN in PLA when near infrared laser (about 800 nm) is not irradiated or irradiated. Near-infrared absorbing gold nanoparticles generate heat and transfer heat to the drug-filled-mesoporous silica shell, which in turn helps desorb and spread the charged drug. By controlling the output of the near-infrared laser, the amount of drug released from the BES was controlled (FIG. 5C). Drug delivery from the stent to the intima was assessed in vivo animal experiments (Fig. 5d).

Thermal mapping at the vascular site is important to ensure precise drug release and prevent heat-induced cell necrosis. Since the areal coverage of the near-infrared laser spot on the temperature sensor is small (about 18% of the total area of the temperature sensor, Fig. 12a), a modified linear correlation (about 0.014 ≪ 0 > C) (the original correlation is Fig. 12b). The light heat experiment setting is shown in Fig. 12C. To demonstrate the effectiveness of the AuNR @ MSN-based thermal therapy, the temperature was monitored in comparison with control group experiments (temperature sensor on BES without AuNR @ MSN). Experimental results show that the temperature rise by about 10 times by including AuNR @ MSN (FIG. 5E). Time-dependent and near-infrared intensity-dependent temperature changes (monitored by an integrated temperature sensor) are shown in Figures 12d and 12e, respectively.

The temperature distribution near and near the BES should be precisely controlled to prevent heat-induced clotting and endothelial cell death. The numerical thermal analysis (Fig. 5F) shows the heat focus area generated by the near-infrared laser at the occlusion (blood flow velocity = 0 mm / s) and reperfusion (blood flow velocity = 2 mm / s, Fig. 47 ° C). Heating (maximum temperature of about 47 ° C) was significantly reduced by blood flow (Figures 12c and 12d) so that the blood temperature around the BES remained below about 43 ° C. The temperature of the inner membrane and the subcutaneous layer in direct contact with the stent decreases non-linearly with respect to depth. A blood flow of 2 mm / s helped to slightly reduce the temperature of the tissue (Figure 5g). Considering the thickness of the inner membrane (approximately 600 [mu] m), thermal conduction to cardiac tissue was tolerated, but not localized, significantly localized to the inner membrane.

Figures 5h-5j show fluorescence photographs of HUVEC after exposure to near-infrared laser radiation with a discontinuous laser power and associated temperature change (Figure 12d). The HUVECs were stained with a LIVE / DEAD survival / cytotoxicity kit (Life technologies, USA) consisting of calcein-AM (green, staining live cells) and ethidium homodimer-1 (red, dead cell stain) . HUVEC survived (Figure 5h) with a slight detectable light mark on green staining by laser when a 17 mW near-infrared laser power was applied for 10 minutes. However, apoptosis (red region) occurred in response to a near-infrared laser output of 29 mW (Fig. 5i). When the near-infrared laser power was further increased to 40 mW, apoptosis was extended to the surrounding area (FIG. 5j). And shown in the quantitative analysis do 5k for cell viability as a function of laser power, which is the conventional report (Brinton. MR et al., Thermal sensitivity of endothelial cells on synthetic vascular graft material, Int. J. Hyperthermia 28, 163- 174 (2012)). The availability of temperature sensors implanted in the BES can help to reduce cell damage and death during diagnosis and treatment. In addition, the controlled hyperthermia treatment potentially prevents the rupture of vulnerable plaques, which can lead to sudden risks such as heart attack and stroke.

Claims (23)

A bioabsorbable flow rate sensor formed adjacent the inner side;
A bioabsorbable nonvolatile resistance memory element formed adjacent to the outer surface;
A bioabsorbable temperature sensor formed adjacent to said bioabsorbable nonvolatile resistance memory element;
A core made of metal nanoparticles which is formed adjacent to the bioabsorbable temperature sensor and generates heat by irradiation with near infrared rays to provide power for drug release, and a drug release nano-particle including a mesoporous silica shell in which a drug is loaded and released A drug delivery layer comprising a biodegradable second polymer layer containing a structure; And
And a biodegradable first polymer layer formed adjacent to the drug delivery layer and containing ceria nanoparticles. The bioabsorbable nonvolatile resistive memory device of claim 1, wherein the bioabsorbable nonvolatile resistive memory element comprises biocompatible electrodes that can be hydrolyzed into a bioabsorbable material and a resistive layer that is hydrolyzable with a bioabsorbable material located between the electrode layers Wherein the bioabsorbable stent is made from a bioabsorbable material. The bioabsorbable electronic stent according to claim 2, wherein the electrode is magnesium or zinc. The bioabsorbable electronic stent according to claim 2, wherein the resistance layer is selected from the group consisting of magnesium oxide, zinc oxide and molybdenum oxide. The bioabsorbable electronic stent according to claim 2, wherein the thickness of the resistive layer is 5 nm to 500 nm. The bioabsorbable electronic stent according to claim 2, wherein the electrode layer has a thickness of 10 nm to 500 nm. The bioabsorbable flow rate sensor of claim 1, wherein the bioabsorbable flow rate sensor comprises biocompatible metal oxide layers that can be hydrolyzed with a bioabsorbable material and a metal layer that is hydrolyzable with a bioabsorbable material located between the metal oxide layers Wherein the bioabsorbable stent is made from a bioabsorbable material. The bioabsorbable electronic stent according to claim 7, wherein the metal oxide of the metal oxide layer is selected from the group consisting of magnesium oxide, zinc oxide and molybdenum oxide. The bioabsorbable electronic stent according to claim 7, wherein the metal of the metal layer is selected from the group consisting of magnesium, iron and zinc. The bioabsorbable electronic stent according to claim 7, wherein the metal oxide layer has a thickness of 5 nm to 500 nm. The bioabsorbable electronic stent according to claim 7, wherein the metal layer has a thickness of 10 nm to 1 mm. The bioabsorbable electronic stent according to claim 1, wherein the ceria nanoparticles have a size of 1 nm to 100 nm. The bioabsorbable electronic stent according to claim 1, wherein the biodegradable first polymer layer is selected from the group consisting of polylactic acid, polyglycolic acid, polyglycerol sebacate, and copolymers thereof. The bioabsorbable electronic stent according to claim 1, wherein the biodegradable first polymer layer is selected from the group consisting of silk, chitosan, starch, hyaluronic acid, gelatin and cellulose. The bioabsorbable electronic stent according to claim 1, wherein the biodegradable first polymer layer has a thickness of 100 nm to 1 mm. The bioabsorbable electronic stent according to claim 1, wherein the metal nanoparticles are gold or silver. The bioabsorbable electronic stent according to claim 1, wherein the metal nanoparticles have a size of 3 nm to 100 nm. The bioabsorbable electronic stent according to claim 1, wherein the mesoporous silica shell has a diameter of 50 nm to 150 nm. The bioabsorbable electronic stent according to claim 1, wherein the drug loaded on the nanostructure is a smooth muscle cell proliferation inhibitor. The bioabsorbable electronic stent according to claim 1, wherein the drug loaded on the nanostructure is rapamycin or paclitaxel. The bioabsorbable electronic stent according to claim 1, wherein the silica shell has a pore diameter of 2 nm to 6 nm. The bioabsorbable electronic stent according to claim 1, wherein the biodegradable second polymer layer is selected from the group consisting of polylactic acid, polyglycolic acid, polyglycerol sebacate, and copolymers thereof. The bioabsorbable electronic stent according to claim 1, wherein the biodegradable second polymer layer is selected from the group consisting of silk, chitosan, starch, hyaluronic acid, gelatin, and cellulose.

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