Wireless remote electrical stimulator and use thereof

Abstract

The present application relates to a kind of wireless remote electric stimulators and its application, by 3D printing full flexible and bioabsorbable stimulator TENG-ST, modulation endogenous electric field, by wireless remote electrotherapy, promote tissue repair, need not additional electronic equipment, with similar to the mechanical properties of soft tissue.

Description

Technical Field

[0001] This invention belongs to the field of functional materials, and specifically relates to a wireless remote electrical stimulator and its application. Background Technology

[0002] Tissue injury is a common physiological phenomenon. Therefore, tissue or organ transplantation is crucial for restoring normal physiological function after severe tissue damage. However, in many cases of injury or disease, stimulating endogenous tissue repair may be an attractive option because it is less invasive and less expensive than tissue or organ transplantation. Furthermore, the endogenous electric field, as the basis for bioelectrical signal transduction, plays a vital role in wound healing, tissue regeneration, and embryonic development. The United States Food and Drug Administration (FDA) has approved electrotherapy, a clinical electrical stimulation (ES) method that mimics the endogenous electric field for tissue repair, improving the tissue growth microenvironment by applying an electric field to modulate the bioelectrical state. However, the scale and complexity of electrotherapy equipment, the potential need for hospitalization for patients, and the requirement for specialized training for physicians pose significant challenges to clinical application.

[0003] Self-powered and portable electrostimulation (ES) devices, such as piezoelectric, triboelectric nanogenerators, electret devices, and radiofrequency devices, have been extensively studied for tissue repair, ensuring greater patient access to electrical stimulation therapy. These studies have made some progress in tissue repair. However, they generally face the following limitations: 1) The device must be adjacent to or in contact with the injured tissue occupying the wound space, thus becoming a physical barrier to tissue repair. Therefore, combining electrotherapy with other clinical treatments can be difficult; 2) The devices are composed of rigid metals, plastics, and inorganic conductors. Rigid devices are incompatible with tissue mechanics, and implantation can easily cause damage to surrounding tissues; 3) Additional encapsulation, wiring, electrodes, or external devices are required to ensure proper functioning of the device, increasing the burden on patients. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a wireless remote electrical stimulator and its application.

[0005] The present invention discloses a triboelectric nanogenerator, wherein the triboelectric nanogenerator is obtained by 3D printing using raw materials containing PGS prepolymer and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate PEDOT:PSS.

[0006] The present invention provides a method for preparing a triboelectric nanogenerator, comprising:

[0007] (1) Mix PGS prepolymer, PEDOT:PSS and NaCl dispersion, stir to obtain 3D printing ink;

[0008] (2) 3D print the ink from step (1), dry, cure, soak, and freeze dry.

[0009] The preferred embodiment of the above preparation method is as follows:

[0010] In step (1), the PGS prepolymer is a mixture of sebacic acid and glycerol, which is stirred and reacted at 130-150℃ for 24-30h under protective gas conditions, and then dehydrated at 135-150℃ for 6-12h to obtain the PGS prepolymer.

[0011] The molar ratio of sebacic acid to glycerol is 1:0.8-1.2.

[0012] In step (1), the PEDOT:PSS dispersion is specifically prepared by stirring, filtering, freeze-drying the PEDOT:PSS aqueous solution, and then dispersing it in a solvent to obtain the PEDOT:PSS dispersion.

[0013] The filtration is performed by filtering the PEDOT:PSS aqueous solution with a 0.22-0.45 micrometer needle filter; the solvent is a mixed solution of deionized water and dimethyl sulfoxide (DMSO).

[0014] In step (1), the mass percentage concentration of the PEDOT:PSS dispersion is 8-12%.

[0015] In step (1), the mass ratio of PGS prepolymer to NaCl particles is 1g:2.0-2.5g; the mass ratio of PGS prepolymer to PEDOT:PSS dispersion is 1g:0.1-1g.

[0016] The specific 3D printing process parameters in step (2) are as follows: rotation angle adjusted to 30-60°, filling distance adjusted to 1.0-1.2 mm, nozzle diameter to 0.5-0.7 mm, and extrusion speed to 0.005-0.008 mm / s. -1 The deposition rate is 4-6 mm / s. -1 The drying process involves drying in a vacuum oven at 90-100℃ for 12-24 hours; the curing process involves curing at 135-150℃ for 24-36 hours.

[0017] The present invention provides a wireless remote electrical stimulator, wherein the wireless remote electrical stimulator includes the triboelectric nanogenerator.

[0018] The present invention relates to the application of the wireless remote electrostimulator in the preparation of tissue repair electrotherapy devices, such as skin repair electrotherapy devices and muscle repair electrotherapy devices.

[0019] This invention presents the feasibility of a fully flexible, bioabsorbable triboelectric nanogenerator (TENG-ST) for wireless remote electrotherapy. 1) Wireless remote electrotherapy can free up wound space and is easily integrated with other clinical treatments. Human tissue contains many ions, and the movement of these ions is the basis of the endogenous extracellular electric field. A general tissue repair strategy is proposed, utilizing the movement of ions in the body to achieve wireless remote electrotherapy, which can prevent possible secondary damage to injured tissue. 2) This invention fabricates a fully flexible, bioabsorbable TENG-ST. Poly(glycerol sebacate) (PGS) is a biodegradable elastomer with a biomimetic modulus similar to soft tissue and resistance to cyclic deformation under dynamic mechanical environments in the body, and was selected as the matrix of TENG-ST. The entire TENG-ST has a modulus that matches that of human soft tissue. 3) Electrotherapy can be performed using an integrated TENG-ST, which is designed to use natural tissue as electronic components, eliminating the need for external power supplies and equipment, additional encapsulation, wires, or electrodes. Furthermore, the TENG-ST can generate an electric field based on the body's spontaneous activity without requiring any electronic components. This study applied the integrated TENG-ST to two animal models: skin defects and muscle injuries, to demonstrate the efficacy of non-proximity electrotherapy. Compared to the control group, the ES treatment group showed significant improvements in tissue repair, indicating that integrating native tissue as part of the device is an effective technique that may inspire next-generation electrotherapy approaches.

[0020] Beneficial effects

[0021] This invention utilizes a stimulator (TENG-ST) based on a 3D-printed, fully flexible, and bioabsorbable triboelectric nanogenerator to modulate an endogenous electric field, promoting tissue repair through wireless remote (approximately 44 mm) electrotherapy. This requires no additional electronic equipment and exhibits mechanical properties similar to soft tissue. Furthermore, the feasibility of using this stimulator to construct wireless remote electrotherapy tissues was demonstrated using skin and muscle injury models. Compared to the control group, the treatment group showed significant improvement in tissue repair. In conclusion, we have developed a promising electrostimulation therapy strategy that may inspire next-generation electrotherapy methods for tissue repair. Attached Figure Description

[0022] Figure 1Schematic diagram of tissue repair, fabrication and microstructure of TENG-STs; (A) Schematic diagram of integrated TENG-STs for tissue repair; (B) Schematic diagram of comprehensive preparation of TENG-STs, including 3D printing, cross-linking, desalting and optical photographs of the prepared TENG-STs; The microstructure of TENG-STs is characterized by scanning electron microscopy, surface (C), cross section (D) and longitudinal section (E), including multi-layer three-dimensional framework, patterned fiber units and interconnected micropores;

[0023] Figure 2 The working principle and performance of TENG-STs; (A) Schematic diagram of the power generation principle of the interaction between a single pore and the tissue; (B) and (C) output performance of TENG-STs containing 1 wt%, 5 wt%, and 10 wt% PPGS were tested under cyclic compressive strain of 40%; (D) Durability test of TENG-STs: output voltage monitored for 1000 cycles (1 Hz) at a compressive strain of 40%; (E) Typical stress-strain curves of TENG-STs prepared with 1 wt%, 5 wt%, and 10 wt% PPGS after 20 cycles at 40% compressive strain, showing good elasticity; (F) Comparison of the modulus of TENG-STs prepared with PPGS with soft tissue, indicating that TENG-STs have a biomimetic modulus similar to that of soft tissue; Yellow pentagram: modulus of TENG-STs; (G) Enzymatic degradation (2000 U / mL lipase), 9 After h, the mass loss of the entire TENG-ST was approximately 95%; (h) Optical images (H) and scanning electron microscope images (I) of TENG-ST during enzymatic degradation, showing good morphology retention ability; (J) Electron output performance of TENG-STs during enzymatic degradation.

[0024] Figure 3To assess the biocompatibility and long-term biosafety of TENG-STs; (A) Cytotoxicity of C2C12 cells by live / dead fluorescent staining: Representative images were labeled with calcein-AM and propidium iodide after 24 h of different treatments, with live and dead cells stained green and red, respectively; (B) Cell counting kit-8 (CCK-8) results of C2C12 cells cultured for 3 days with PGS and samples prepared with 1 wt%, 5 wt%, and 10 wt% PPGS (**p<0.01, ***p<0.001); (C) Local inflammatory response: Hematoxylin and eosin (H&E) staining results of tissues surrounding subcutaneous implants in rats at 7 and 28 days post-surgery, with black arrows indicating inflammatory cells and yellow stars indicating implanted material; (D) Control group (healthy rats) and subcutaneous implanted 5 wt% H&E staining images of major organs (heart, liver, spleen, lung and kidney) of SD rats in PPGS samples at 7 days;

[0025] Figure 4 Application of TENG-STs in a rabbit rectus femoris rupture model; (A) Schematic diagram of TENG-ST applied to a rabbit muscle repair model; Histological examination of rabbit rectus femoris at 4 weeks (B) and 8 weeks (C) (H&E and Masson's trichrome staining); Representative H&E staining images show no inflammatory changes in the regenerated rectus femoris tissue of the control group, PGS group, and ES group; Representative Masson's trichrome staining images show the regenerated muscle fibers (red) and collagen matrix (blue) of the control group (untreated), PGS group, and ES group, n=4; (D) Quantitative analysis of muscle fiber area stained by Masson's trichrome staining after 8 weeks of treatment in the control group, PGS group, and ES group (**p<0.01, ***p<0.001), n ​​= 4; (E) Immunofluorescence staining of wound, typical immunofluorescence staining of myosin H-expressing muscle cells (red) and CD31-expressing endothelial cells (green) at 8 weeks, quantitative myosin H-expressing wound staining after 8 weeks of treatment. H density (F) and quantitative CD31 density (G) (**p<0.01, ***p<0.001);

[0026] Figure 5The application of TENG-STs in a rat full-thickness skin defect model; (A) Schematic diagram of the integrated TENG-STs applied to a rat full-thickness wound; (B) Macroscopic photographs of the proximal wound, distal wound, and control group (untreated) incisions at different time points; (C) Remaining wound area after 0, 3, 7, 10, and 14 days of treatment (*p<0.05, **p<0.01, ***p<0.001). n=4; (D) Compared with the control group, the repair efficiency was improved on day 3, with the proximal wound group showing an 885% higher repair efficiency than the control group, and the distal wound group showing a 336% higher repair efficiency than the control group; (E) This work compares the repair efficiency of the current work with previously reported electrotherapy work on skin wound healing, demonstrating higher repair efficiency; (F) Histological examination of the wound area at 7 and 14 days after treatment, with representative Masson trichrome staining images showing regenerated collagen matrix in the proximal wound, distal wound, and control group. Black arrows: blood vessels; blue dashed lines: the boundary between the wound area and normal tissue; (G) Quantitative analysis of Masson staining collagen area in the proximal wound group, distal wound group, and control group 14 days after treatment (**p<0.01, ***p<0.001). n=4; (H) Immunofluorescence staining of wound, typical immunofluorescence staining of CD31-expressing endothelial cells (red) and α-SMA-expressing pericytes (green) on day 14; quantitative CD31 density (I) and quantitative α-SMA density (J) after 14 days of treatment (**p<0.01, ***p<0.001). Detailed Implementation

[0027] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0028] Sebacic acid: 99%, Aladdin;

[0029] Glycerin: 99.5%, Sigma-Aldrich;

[0030] PEDOT:PSS aqueous solution: Clevios™ PH1000, Heraeus Electronic Materials.

[0031] Example 1

[0032] (1) Preparation of PGS prepolymer:

[0033] An equimolar mixture of sebacic acid and glycerol was heated at 150°C under a nitrogen atmosphere for 3 hours with stirring at 1000 rpm to obtain a homogeneous mixture. After 24 hours, vacuum treatment was performed to remove water from the mixture. Finally, stirring was stopped at 300 rpm to obtain the PGS prepolymer.

[0034] (2) Preparation of 3D printing ink:

[0035] The PEDOT:PSS aqueous solution was first stirred for 12 h and then filtered using a 0.45 μm syringe filter. The resulting PEDOT:PSS solution was then frozen in liquid nitrogen. The cryogenically frozen PEDOT:PSS solution was then freeze-dried for 48 h to obtain solid PEDOT:PSS. The solid PEDOT:PSS was then redissolved in deionized water / dimethyl sulfoxide (DMSO) (Adamas) (85 / 15, v / v) to obtain a 10% PEDOT:PSS dispersion. NaCl particles were obtained from Sigma-Aldrich. The PGS prepolymer was mixed with NaCl particles at a ratio of 1:2.5, and then added to the PEDOT:PSS dispersion to obtain mixtures with PEDOT:PSS comprising 1%, 5%, and 10% of the PGS mass fraction. After stirring, 3D printing inks (i.e., 1 wt%, 5 wt%, and 10 wt% PPGS inks, respectively) were obtained.

[0036] (3) 3D printing process and micromorphological characterization

[0037] 3D printing was performed using a commercial pressure-controlled ink direct-write 3D printing system (BS4.2, GESIM). The shape was then designed using C4D and GeSim Robotics. The rotation angle was adjusted to 45°, and the infill distance to 1.2 mm. The nozzle diameter was 0.7 mm, and the extrusion speed was 0.005 mm / s. -1 The deposition rate was 4 mm / s. -1 Gesim Robotics fully controlled the printing process. The printed parts were then placed in a vacuum oven at 90°C (0.5 bar) for 12 hours and cured at 135°C (1 bar) for 24 hours. The samples were then immersed in deionized water for 24 hours, with the water changed every 6 hours to completely remove NaCl particles. Finally, they were freeze-dried to obtain complete TENG-STs.

[0038] Furthermore, the microstructure of the integrated TENG-STs was investigated using a scanning electron microscope (HITACHI SU8010) equipped with an EDS detector. Additionally, thermogravimetric analysis (TGA) of the integrated TENG-STs was performed using Discovery TGA (TA, USA) at a temperature range of 30–400°C and a heating rate of 10°C / min. -1 Under a nitrogen atmosphere.

[0039] Mechanical properties of TENG-STs

[0040] The mechanical properties of the integrated TENG-STs were evaluated using a universal testing machine equipped with a 100-N sensor (MTS Exceed E42, USA). The length, width, and thickness of the TENG-STs were measured and input into the software (TestSuite TW). Uniaxial and cyclic compression tests were performed at 30 mm min. -1 At a cross velocity, the compressive strain was set to 40% of the TENG-STs thickness. Finally, the number of cycles in the cyclic compression test was set to 20. The mechanical properties of TENG-STs prepared with different printing inks were characterized using an Instron 5969 universal testing machine equipped with a 5000-N sensor.

[0041] Electrical properties of TENG-STs

[0042] Electrical output performance was measured using a Keithley 6514 instrument. First, complete TENG-STs were fabricated, all identical in size, measuring 14 mm × 14 mm × 5 mm (length × width × height). Then, the TENG-STs were fixed to one end, with a polyimide film coated on the other end. During voltage and current output measurements, the TENG-STs were impacted at a frequency of 1 Hz with 40% strain. Finally, a durability test was performed on the TENG-STs under the same conditions for 1000 s.

[0043] Degradation performance of TENG-STs

[0044] The degradability of TENG-STs was investigated using enzymatic degradation experiments. First, 0.2 g of 20000 U / g lipase (AdamasLife) was added to 2 mL of phosphate-buffered saline (PBS) to prepare a 2000 U / mL lipase solution. TENG-STs measuring 10 mm × 10 mm × 3 mm (length × width × height) were weighed (M0) and placed in the lipase solution at 37℃, n = 3. After the predetermined time, the TENG-STs were removed, and the remaining lipase was washed with PBS. After freeze-drying, the mass of the TENG-STs (Mt) was weighed using an electronic balance. Finally, the degradation rate of the sample was determined according to the following formula:

[0045] Degradation rate (%) = (M0 – M) t ) / M0 × 100

[0046] TENG-ST's cytotoxicity

[0047] In short, samples prepared from PGS and 1 wt%, 5 wt%, and 10 wt% PPGS were sterilized and placed in 6-well plates at a solid-liquid ratio of 0.1 g / mL. Then, the samples were plated at 1 × 10⁻⁶. 6 C2C12 cells (ATCC CCL-1) were seeded at 37°C and incubated in 5% CO2 medium. The culture medium was prepared as 90% Dulbecco's modified Eagle's medium (DMEM, Gibco) and 10% fetal bovine serum (FBS, Gibco), with 100 units / mL penicillin G and 100 µG / mL streptomycin (Gibco) added. After 24 h, the medium was discarded, and TENG-STs were removed. The remaining cells in the 6-well plates were stained according to the live / dead cell cytotoxicity assay kit (Beyotime, China). Live and dead cells were then labeled with calcein-AM and propidium iodide, visible as green and red fluorescent images, respectively, and recorded under a microscope. Finally, the ratio of live to dead cells was analyzed based on fluorescence intensity.

[0048] Effects of TENG-STs on cell viability

[0049] Cell proliferation activity was evaluated according to the instructions of the 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay kit (Beyotime, China). In short, after 3 days of co-culturing, MTT solution (1:10) was added to the culture medium and incubated for 4 hours, then the supernatant was discarded. 100 µL of formazan solution was added and mixed until the blue-violet crystals were completely dissolved. The optical density (OD) value of this solution was measured at 570 nm using a microplate spectrophotometer (Thermo Scientific).

[0050] TENG-ST's in vivo biosafety

[0051] Animal experiments in this study were conducted according to the standard protocol approved by the Animal Ethics and Use Committee of the Stomatological Hospital Affiliated to Fudan University. Experimental animals were provided by Shanghai JSJ Laboratory Animal Co., Ltd. Male SD rats (8-9 weeks old, weighing 160-220 g) were anesthetized and intraperitoneally injected with 1% sodium pentobarbital (30 mg / kg), with 3 rats per group. A 10 mm incision was made in the skin at the midline of the rat's back, and a subcutaneous pouch was formed by blunt dissection. A 10 mm × 10 mm × 5 mm (length × width × height) integrated TENG-STs was implanted, and the wound was sutured. Rats were euthanized and dissected on days 7 and 14, respectively. Materials, surrounding skin, and vital organs such as the heart, liver, spleen, lungs, and kidneys were collected. Material degradation was recorded, and H&E staining of tissue sections was used to analyze the inflammatory infiltration around the materials and the toxicity to vital organs.

[0052] The role of wireless remote electrical stimulation in muscle repair

[0053] Twelve adult New Zealand white rabbits (weighing 2.0–2.5 kg, male and female) were selected to observe the in vivo muscle repair-accelerating effect of TENG-STs prepared with 5 wt% PPGS. They were divided into three groups: an ES group, a PGS group, and a control group (n=4 per group). The integrated TENG-STs in the ES group were prepared using 5 wt% PPGS, while the materials in the PGS group were prepared using PGS with the same structure as the ES group. However, the control group only received surgical treatment. In short, anesthesia was administered via intravenous injection of 3% sodium pentobarbital (30 mg / kg) into the rabbit's ear. The surgical site was disinfected, and an incision was made on the lateral aspect of the femur under aseptic conditions. The fascia was dissected layer by layer, exposing the quadriceps femoris muscle to the rectus femoris, vastus lateralis, and vastus medialis muscles. The rectus femoris was transversely cut 15 mm above the patella. The rectus femoris was then sutured in layers, ensuring a smooth anastomosis without exposing the muscle bundles. An arched, integrated TENG-ST measuring 15 mm × 10 mm × 2.5 mm (length × width × thickness) was applied to the wound, and the wound was tightly sutured. Post-surgery, the rabbit was given antibiotics (Aladdin, China) and kept in a cage to prevent infection.

[0054] New Zealand rabbits were euthanized at 4 and 8 weeks of age, respectively. First, the rabbits were photographed. Then, tissue samples from the proximal and distal ends of the implanted TENG-STs were cut and fixed in paraformaldehyde solution (Servicebio, China) to prepare tissue sections. Hematologic and Escherichia coli (H&E) staining was used to evaluate wound inflammation. Masson staining was used to evaluate myofibrous repair in the wound tissue.

[0055] The role of wireless remote electrical stimulation in skin repair

[0056] Eighteen male SD rats (8-9 weeks old, 160-220 g) were selected to observe the effect of TENG-STs prepared with 5 wt% PPGS on promoting skin wound healing. All rats were divided into three groups of six each: untreated wounds (control group), wounds distal to TENG-STs (distal wound group), and wounds proximal to TENG-STs (proximal wound group). Anesthesia was administered via intraperitoneal injection of 1% sodium pentobarbital (30 mg / kg). The surgical area was disinfected. Under aseptic conditions, two circular full-thickness skin wounds, each 12 mm in diameter, were created along the midline of the rat's dorsal spine using tissue scissors. The distance between the two wounds was 30 mm. An arched TENG-ST measuring 34 mm × 10 mm × 3 mm (length × width × thickness) was fixed above the wound, 2 mm from the incision edge, and an integrated TENG-STs were fixed with a sterile wound dressing. Postoperatively, antibiotics (Aladdin, China) were administered to prevent wound infection. Observe and photograph the changes in skin wounds on days 0, 3, 7, 10, and 14. ImageJ software was used to analyze the wound area, and the following formula was used to evaluate the effect of ES on wound healing. Within each group, the best and worst performing groups were removed, and the remaining groups were analyzed.

[0057] Repair efficiency = (1 - Wound area on day N / Original wound area) × 100%

[0058] Rats were euthanized at 3, 7, 10, and 14 days, and skin tissue samples were collected around the wounds. These samples were fixed in 10% neutral formalin (Servicebio, China) and sectioned in paraffin. After dewaxing, the paraffin sections were stained with H&E and Masson staining according to the instructions of a commercial kit (Beyotime, China). The remaining sections were immunohistochemically stained with angiogenesis marker CD31 and α-SMA (Proteintech, China). In summary, antigen retrieval was performed on the sections using a modified citrate antigen retrieval solution (Beyotime, China), followed by light blocking for 1 h with immunostaining wash solution (Beyotime, China) and 10% goat serum antibody (Servicebio, China), and then diluent for the primary antibody was added. After incubation overnight at 4°C, the sections were treated with the nuclear dye DAPI, washed with PBS for 15 minutes, wiped dry, and sealed. The wound inflammation, collagen deposition, and angiogenesis were observed under a microscope. ImageJ software was used to measure the number of collagen fibers in the wound and analyze the fluorescence intensity of immunomarkers to evaluate the wound healing effect.

[0059] like Figure 1As shown in Figure B, TENG-STs were fabricated using 3D printing ink, comprising poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), a PGS matrix (PPGS), and NaCl particles. The microstructure of the TENG-STs was characterized using scanning electron microscopy. The PEDOT:PSS portion was exposed, with the remainder embedded in the PGS matrix. Furthermore, from the surface ( Figure 1 C) Cross-section ( Figure 1 D) and longitudinal section ( Figure 1 E) The layered structure of TENG-STs (5 wt% PPGS) is clearly visible. The patterned arrangement of the primary multilayer structures (such as arches and hollow cylinders) and secondary fiber units was customized using 3D printing models. Furthermore, the tertiary structure consists of interconnected micropores within filaments formed by leaching NaCl particles, which is fundamental to ensuring the overall proper functioning of TENG-STs.

[0060] like Figure 2 As shown in Figure A, the working principle of TENG-STs is achieved through compression deformation, which causes the PGS and PEDOT:PSS to separate upon contact. When the micropores are compressed, the exposed PEDOT:PSS contacts the PGS matrix and becomes positively charged due to its weaker ability to trap electrons. Similarly, the PGS matrix becomes negatively charged. Furthermore, due to the good elasticity of the micropores, they gradually return to their original shape after the force is removed. PEDOT:PSS still carries a positive charge when in contact with the tissue, which leads to the accumulation of anions in the tissue to balance the potential. Simultaneously, cations in the tissue migrate distally, forming an electrical double layer. When the micropores return to their original shape, the separation distance between the PGS matrix and PEDOT:PSS reaches its maximum, and the charge reaches equilibrium. However, when the micropores are recompressed, a transient current in the opposite direction is generated to balance the potential.

[0061] Therefore, to evaluate the effect of different PEDOT:PSS mass fractions on the performance of TENG-STs, inks with 1 wt%, 5 wt%, and 10 wt% PPGS were prepared, and TENG-STs with dimensions of 14 mm × 14 mm × 5 mm (length × width × height) were fabricated. The electrical output of TENG-STs with different PEDOT:PSS ratios is shown below. Figure 2 As shown in B and 2C. The results show that the integrated TENG-STs with 5 wt% PPGS have the best electrical output performance, with peak open-circuit voltage and peak short-circuit current of 2.5 V and 178 nA, respectively. The poor electrical performance of the TENG-STs prepared with 1 wt% PPGS can be attributed to their non-conductivity, which prevents them from acquiring electrical signals. Furthermore, as... Figure 2As shown in Figure D, taking TENG-STs prepared with 5 wt% PPGS as an example, TENG-STs exhibit good long-term electrical output stability. Furthermore, the voltage increases slightly due to the accumulation of triboelectric charge.

[0062] It is worth noting that the mechanical properties of TENG-STs play an important role in tissue repair. In cyclic compression experiments, TENG-STs exhibited excellent elasticity and negligible hysteresis after 20 cycles at a compressive strain of 40%, which is the basis for long-term stable electrical output. When the compressive strain is 40%, the compressive strength and modulus of TENG-STs increase slightly with the increase of PEDOT:PSS content, which may be due to the toughening effect of PEDOT:PSS in the PGS matrix. Figure 2 F compared the modulus of integrated TENG-STs with that of soft tissue. The elastic moduli of TENG-STs prepared with PGS, 1 wt%, 5 wt%, and 10 wt% PPGS were 77.2 ± 5.1 kPa, 82.8 ± 7.8 kPa, 173 ± 33 kPa, and 242 ± 22 kPa, respectively. Furthermore, these values ​​are similar to the modulus of human soft tissues such as skin (420–750 kPa) and muscle tissue (approximately 170 kPa), which can help avoid damage to surrounding tissues after implantation.

[0063] The degradability of the implanted device is crucial to avoiding secondary surgical resection and patient trauma. Therefore, a very high concentration of enzyme solution (2000 U / mL lipase solution) was used to significantly accelerate the degradation process, mimicking the degradation capacity of TENG-STs. The degradation curve of TENG-STs prepared with 5 wt% PPGS is shown below. Figure 2 As shown in G. Under the action of lipase, the mass loss reached 94.99±1.56% after 9 h. Photos of TENG-STs during the degradation process are shown below. Figure 2 As shown in H, TENG-STs exhibited good morphology retention during degradation. Figure 2 I). Electrical output performance during enzyme degradation, such as Figure 2 As shown in Figure J, the output voltage of TENG-ST steadily decreases with mass loss. Even when the mass loss reaches approximately 60%, TENG-ST still maintains a peak voltage of 0.45V. Previous studies have shown that ES values ​​of 100-150 mV / mm can effectively promote protein expression and accelerate wound healing. Overall, TENG-ST effectively generates ES to promote tissue repair for most of the degradation period.

[0064] Before conducting in vivo wireless remote electrotherapy for tissue repair, the biocompatibility and long-term safety of TENG-STs must be considered. Therefore, cell compatibility was evaluated by observing cell morphology and proliferation after co-culturing TENG-STs with C2C12 cells. Interestingly, PPGS with a PEDOT:PSS mass fraction of ≤5 wt% exhibited good biocompatibility and had minimal impact on the survival and proliferation of C2C12 cells, while cells prepared with 10 wt% PPGS showed poorer cell compatibility. Figure 3 A). The results of the cell counting kit-8 (CCK-8) viability assay were similar to those of cell live / dead staining. PGS, 1 wt% and 5 wt% PPGS had no significant effect on cell viability, but 10 wt% PPGS inhibited cell growth and reduced cell viability. Figure 3 B).

[0065] In addition, a rat subcutaneous implantation model was established to detect local inflammation and systemic immune response of TENG-STs. Notably, the PGS group was completely absorbed, while the other three groups showed material degradation and volume reduction 28 days after implantation. Figure 3 C). Furthermore, hematoxylin and eosin (H&E) staining of the surrounding tissue at 7 and 28 days showed that the pathological inflammatory response in the tissue surrounding TENG-STs prepared with 5 wt% PPGS was less. Therefore, considering the mechanical properties, electrical output, and biocompatibility of the material, TENG-STs prepared with 5 wt% PPGS were selected for tissue repair.

[0066] In addition, to further evaluate the biocompatibility of the integrated TENG-STs prepared with 5 wt% PPGS, H&E staining was performed on the major organs (heart, liver, spleen, kidney, and lung) of rats 7 days after subcutaneous implantation of the 5 wt% PPGS material. Figure 3 D). H&E staining showed no signs of systemic immunity, including abnormal lymphocytes or organic lesions invading vital organs. Overall, TENG-STs prepared with 5 wt% PPGS exhibited good biocompatibility and biosafety, making them suitable for in vitro and in vivo experiments with ES devices.

[0067] To verify the electrotherapy strategy of TENG-STs regulating tissue ion flow, a rabbit rectus femoris muscle repair model was established. Figure 4 A). At 4 and 8 weeks, the muscle defect area was stained with H&E and Masson's trichrome stain. (e.g.) Figure 4As shown in Figure B, the material was not completely degraded in the early stage of muscle repair (4 weeks), and no obvious inflammatory response or fibrous capsule encapsulation was observed around the implanted material. In contrast, the material was completely absorbed after 8 weeks. Compared with the PGS group and the control group, the muscle fibers in the ES group were densely and regularly distributed; while the muscle fibers in the control group were broken and irregularly distributed. Figure 4 C). Quantitative analysis of Masson staining in the muscle rupture area during the late repair phase (8 weeks) showed that the proportion of muscle fiber area in the ES group (72.13±7.73%) was significantly higher than that in the PGS group (33.12±6.65%) and the control group (9.53±5.04%). Figure 4 D).

[0068] It is worth noting that myofibril formation plays a crucial role in muscle repair. Therefore, to further evaluate the effect of integrated TENG-STs on the repair of rectus femoris rupture in rabbits, immunofluorescence analysis of myosin skeletal heavy chain (Myosin H) and vascularization marker CD31 was performed on the injured tissue. Figure 4 E). In the ES group, the expression of Myosin H and CD31 in new tissues was higher than in other groups. Figure 4 (F and 4G) indicates that wireless remote electrotherapy can accelerate early angiogenesis, myofibril formation and remodeling, and improve muscle repair efficiency.

[0069] A rat model of full-thickness defect was established to further validate the wireless remote electrotherapy strategy. Figure 5 As shown in Figure A, proximal wound (close to TENG-STs, approximately 2 mm) and distal wound (far from TENG-STs, approximately 44 mm) groups were set up based on the distance between the TENG-STs and the wound. Conversely, the control group (untreated) was placed on the back of another rat. Figure 5 B represents the wound healing process. As expected, wounds treated with TENG-STs healed better than the control group at all times. Furthermore, significant differences existed among the three groups. Quantitative analysis of wound area showed that after 3 days, the proximal wound significantly shrank to 51.30±3.14% of its initial size, while the distal wound and control group showed reductions of 22.71±7.87% and 5.21±3.81%, respectively. Figure 5 C). Furthermore, the repair efficiency of the proximal wound group (885%) and the distal wound group (336%) on day 3 was significantly higher than that of the control group (100%). Figure 5 D). Here, repair efficiency refers to the percentage increase in repair efficiency between the experimental groups (proximal and distal wound groups) and the control group. However, the repair efficiency of this study on the skin defect model on day 3 was significantly higher than previously reported electrotherapy studies ( Figure 5 E).

[0070] During tissue repair, normal skin tissue structures (skin appendages and subcutaneous muscle) extend towards the wound center. Furthermore, connective tissue in the wound area is remodeled and re-epithelialized. Masson staining was used to evaluate the number of new blood vessels and collagen regeneration at the wound site. The number of new blood vessels near the proximal end of the wound was significantly higher than in other groups, and collagen levels were one of the main markers of wound healing. Figure 5 F). The collagen content in the distal wound (29.53±6.13%) and proximal wound (47.35±3.18%) was significantly higher than that in the control group (13.91±2.81%). Figure 5 G). Therefore, the above results indicate that wireless remote electrotherapy can promote wound healing and accelerate collagen deposition.

[0071] Angiogenesis, reepithelialization, and collagen synthesis play crucial roles in skin wound healing. Therefore, immunofluorescence characterization using the vascularization marker CD31 and α-smooth muscle actin (α-SMA) was employed to further monitor neovascularization during wound healing. Furthermore, histochemical fluorescent labeling was used to detect new blood vessels around the wound to further evaluate the effect of combined TENG-STs electrotherapy on wound healing. Figure 5 H). Furthermore, compared to other groups, the expression of α-SMA and CD31 was increased in neoplastic tissue of the proximal wound group (H). Figure 5 I and 5J) indicate that ES can accelerate wound closure by promoting angiogenesis.

[0072] This invention promotes tissue repair by modulating an endogenous electric field. Wireless remote electrotherapy is achieved using the completely soft, bioabsorbable elastic TENG-ST, eliminating the need for additional electronic attachments. Interestingly, this strategy frees up wound space, prevents potential secondary damage, and makes treatment of injured tissue more convenient. Furthermore, in the future, wireless remote electrotherapy may be used in conjunction with other local treatment systems for damaged tissue repair. Therefore, integrating native tissue as part of the device can pave the way for new treatment devices and inspire new implantation strategies.

Claims

1. A wireless remote electrical stimulator, characterized in that, The wireless remote electrical stimulator includes a triboelectric nanogenerator, wherein the triboelectric nanogenerator is obtained by 3D printing from a raw material containing PGS prepolymer and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate PEDOT:PSS, wherein PEDOT:PSS accounts for 5% of the mass fraction of PGS; The method for preparing the triboelectric nanogenerator includes: (1) Mix PGS prepolymer, NaCl, and PEDOT:PSS dispersion, stir, and obtain 3D printing ink; (2) 3D print the ink from step (1), dry, cure, soak, and freeze-dry; the specific process parameters for 3D printing are: rotation angle adjusted to 30-60°, filling distance adjusted to 1.0-1.2 mm, nozzle diameter to 0.5-0.7 mm, and extrusion speed to 0.005-0.008 mm / s. -1 The deposition rate is 4-6 mm / s. -1 .

2. The wireless remote electrical stimulator according to claim 1, characterized in that, In step (1), the PGS prepolymer is a mixture of sebacic acid and glycerol, reacted under a protective gas at 135-150℃ for 24-30 hours with stirring to remove water, thus obtaining the PGS prepolymer.

3. The wireless remote electrical stimulator according to claim 1, characterized in that, In step (1), the PEDOT:PSS dispersion is specifically prepared by stirring, filtering, freeze-drying the PEDOT:PSS aqueous solution, and then dispersing it in a solvent to obtain the PEDOT:PSS dispersion.

4. The wireless remote electrical stimulator according to claim 3, characterized in that, The filtration process involves filtering the PEDOT:PSS aqueous solution using a 0.22-0.45 micrometer needle filter; the solvent is a mixed solution of dimethyl sulfoxide (DMSO) and water.

5. The wireless remote electrical stimulator according to claim 1, characterized in that, In step (1), the mass percentage concentration of the PEDOT:PSS dispersion is 8-12%.

6. The wireless remote electrical stimulator according to claim 1, characterized in that, In step (1), the mass ratio of PGS prepolymer to NaCl is 1:2.0-2.

5.

7. The wireless remote electrical stimulator according to claim 1, characterized in that, In step (2), drying is performed in a vacuum oven at 90-100℃ for 12-24 hours; curing is performed at 135-150℃ for 24-36 hours.

8. The application of the wireless remote electrical stimulator of claim 1 in the preparation of a tissue repair electrotherapy device.

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