Zinc-doped bismuth telluride nanorod as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of nano bismuth telluride, and relates to a zinc-doped bismuth telluride nanorod as well as a preparation method and application thereof. In the zinc-doped bismuth telluride nanorod, the molar ratio of Bi elements to Zn elements to Te elements is (0.85 to 0.95) to (0.05 to 0.15) to 1.5. The zinc-doped bismuth telluride nanorod is synthesized, the capability of promoting generation of reactive oxygen species (ROS) is better, and H2O2 generated by the zinc-doped bismuth telluride nanorod is as high as 12.0 mu M after cold exposure for 30 min. Meanwhile, the activity of the methicillin-resistant staphylococcus aureus is reduced by 92.76% through the zinc-doped bismuth telluride nanorod, the spherical structure of the methicillin-resistant staphylococcus aureus is damaged, and the bacterial form and cell membrane are not complete any more.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanometer bismuth telluride, and relates to zinc-doped bismuth telluride nanorods as well as a preparation method and application thereof. BACKGROUND

[0002] Chronic wound healing remains a major clinical challenge, mainly due to bacterial infection and persistent inflammatory response. These factors not only disrupt the natural healing process, but can also lead to serious complications such as systemic infection or organ dysfunction. Traditional wound treatment relies on antibiotics and non-interacting dressings. These methods often fail to address the dynamic microenvironment of the wound, especially in drug-resistant infections such as methicillin-resistant Staphylococcus aureus (MRSA). With the increasing threat of antibiotic resistance, there is an urgent need to develop non-antibiotic-dependent wound care methods. Although photothermal, photodynamic, and sonodynamic therapies show therapeutic potential, they cannot simultaneously address inflammation control, pain relief, and tissue regeneration issues. These limitations often require additional treatments such as anti-inflammatory drugs or growth factors.

[0003] The prior art CN119101259A discloses a preparation method of a near-infrared responsive thermoelectric temperature-sensitive supramolecular injectable hydrogel: bismuth nitrate pentahydrate and thioacetamide are dissolved in deionized water to obtain Bi2S3 nanoparticles, and the Bi2S3 nanoparticles are put into a tannic acid TA aqueous solution to obtain Bi2S3@TA nanoparticles; NIPAM, VI, disulfiram and azobisisobutyronitrile are added to the mixed solution obtained after dissolving in an organic solvent and heated to obtain a supramolecular temperature-sensitive polymer PNV; SA, TA, PNV and Bi2S3@TA are dissolved in physiological saline, the obtained mixed solution is injected into a mold, and a metal salt solution is sprayed to obtain a thermoelectric temperature-sensitive supramolecular injectable hydrogel. The injectable hydrogel completes active contraction and thermal-electric stimulation under the input of single near-infrared energy, can be used as a photothermal platform to reduce bacterial load, and promotes the repair of infected wounds. However, the prior art generates photothermal effect by near-infrared light to induce the thermoelectric effect of Bi2S3 to achieve therapeutic effect. Excessive photothermal effect will cause thermal damage to normal tissues, and the organic compounds and organic solvents used are unsafe materials for the human body, which poses a safety hazard.

[0004] The prior art proposes a treatment strategy of "low-temperature medicine", that is, to achieve biomedical applications by using precisely controlled low temperature. Low-temperature medicine takes advantage of the specific biological effects of low temperature, such as metabolic inhibition, to reduce oxygen demand and cell protection, and achieves pain relief by selectively inhibiting nerve conduction velocity. However, current cryotherapy methods rely on manual temperature control, resulting in poor precision and efficacy.

[0005] The prior art CN 115956583 A relates to a copper-bismuth telluride nanorod antibacterial active material, which is a bismuth telluride nanorod material doped with a copper lattice, and the length of the nanorod is less than or equal to 250 nm. The invention also includes the preparation and application of the material. The material described in the invention has good temperature difference stimulation sensing ability and can effectively promote ROS release, and has good antibacterial performance. However, excessive copper in the prior art can be toxic to cells and the human body. SUMMARY

[0006] The purpose of the present application is to provide a zinc-doped bismuth telluride nanorod and its preparation method and its application in thermoelectric therapy.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0008] A zinc-doped bismuth telluride nanorod, wherein the molar ratio of Bi, Zn and Te elements is 0.85-0.95:0.05-0.15:1.5.

[0009] The ratio of Zn 0.05 corresponds to the zinc doping amount in BZT-1 (0.106 mol%), and the ratio of Zn 0.15 corresponds to the zinc doping amount in BZT-3 (0.302 mol%).

[0010] The present application forms BZT-x nanorods by doping with zinc (Zn), which realizes the dual improvement of antibacterial property and ROS generation ability. The introduction of Zn enhances the ROS generation ability and improves the antibacterial property, and effective treatment can be achieved at a low dose. There is an electronic structure regulation effect between Zn and the bismuth telluride matrix, which enhances the temperature catalytic or electrocatalytic activity, thereby improving the generation efficiency of therapeutic ROS.

[0011] Since the radius of Zn ion is different from that of Bi, the doping amount will significantly affect the performance of the material. Too little doping will result in insufficient ROS generation ability and antibacterial performance; excessive doping will cause lattice distortion or phase separation, change the energy band structure of bismuth telluride, and affect the ROS generation ability and material stability.

[0012] According to the embodiments of the present application, the present application can be further optimized, and the following is the technical solution formed after optimization:

[0013] In one preferred embodiment, the molar ratio of Bi, Zn and Te elements is 0.88-0.92:0.08-0.12:1.5.

[0014] Based on the same inventive concept, the present application also claims the preparation method of the zinc-doped bismuth telluride nanorod, which comprises the following steps:

[0015] The tellurium source, alkali, surfactant, solvent and reducing agent are subjected to a first-stage reaction at 150-155°C; then the bismuth source is added to perform a second-stage reaction at 150-155°C; then the reducing agent and zinc source are added to perform a third-stage reaction at 150-155°C, and precipitation is performed to obtain the zinc-doped bismuth telluride nanorods.

[0016] The molar ratio of Te in the tellurium source, Bi in the bismuth source and Zn in the zinc source is 0.85-0.95:0.05-0.15:1.5.

[0017] In one preferred embodiment, the tellurium source is one or more of tellurium oxoacid salts, metallic tellurium or tellurides; preferably at least one of sodium tellurite, tellurium powder or sodium telluride.

[0018] In one preferred embodiment, the alkali is at least one of sodium hydroxide and potassium hydroxide.

[0019] In one preferred embodiment, the surfactant is at least one of polyvinylpyrrolidone and polyethylene glycol.

[0020] In one preferred embodiment, the solvent is at least one of ethylene glycol and glycerol.

[0021] In one preferred embodiment, the reducing agent is one of hydrazine hydrate, ascorbic acid or sodium borohydride.

[0022] In one preferred embodiment, the weight ratio of the tellurium source, alkali, reducing agent and surfactant is 1:1.2-3:8-15:0.7-1.2.

[0023] The amount of the tellurium source, alkali and reducing agent will significantly affect the reduction degree, morphology, crystallinity and impurity content of the bismuth telluride nanorods. Too much or too little will cause the generation of by-products, incomplete reaction or morphology out of control, and the target product cannot be obtained. The role of the tellurium source is to provide Te 6+ and participate in the reduction to form Bi2T3. Too much tellurium source will cause the Te 6+ concentration in the system to be too high, and non-target phases such as TeO2 or Te nanoparticles may be generated. Too little tellurium source will not form complete Bi-Te compounds, and by-products such as Bi nanoparticles or BiOCl may be generated.

[0024] Too much alkali will cause the system to be too basic, which may cause Bi 3+ to hydrolyze to form Bi(OH)3 or Bi2O3 precipitates, affecting the reaction efficiency, the stability of the tellurium source and the stability of the surfactant, and causing the particle size distribution to be wide. Too little alkali will not be enough to promote the reduction reaction, causing incomplete reaction.

[0025] Too much reducing agent will reduce Bi3+ reduced to metallic Bi, or Te 6+ reduced to elemental Te, resulting in metallic impurities in the product, affecting electrical properties and morphology. Too little reducing agent, Bi or Te in oxidized state remains, forming impure phases such as BiOCl, TeO2, affecting product purity; poor crystallinity, uneven particle size, affecting performance.

[0026] Likewise, too much or too little surfactant affects product morphology and purity.

[0027] In one preferred embodiment, the first reaction is carried out for 0.5-1.5 h.

[0028] In one preferred embodiment, the bismuth source is a bismuth salt, preferably at least one of a nitrate or a chloride.

[0029] In one preferred embodiment, the second reaction is carried out for 0.5-1.5 h.

[0030] In one preferred embodiment, the zinc source is a zinc salt, preferably at least one of a nitrate or a chloride.

[0031] In one preferred embodiment, the third reaction is carried out for 0.5-1.5 h.

[0032] In one preferred embodiment, the solvent used for precipitation is one or more of acetone, ethanol, tetrahydrofuran, and methanol.

[0033] Based on the same inventive concept, the present application also claims the use of the zinc-doped bismuth telluride nanorods in the preparation of a drug gel.

[0034] Based on the same inventive concept, the present application also claims the use of the zinc-doped bismuth telluride nanorods in the preparation of an agent for promoting repair of infected wounds.

[0035] In one preferred embodiment, the infected wound is a diabetic ulcer or a burn-induced infected wound.

[0036] Based on the same inventive concept, the present application also claims the use of the zinc-doped bismuth telluride nanorods in the preparation of an antibacterial agent.

[0037] In one preferred embodiment, the bacteria is methicillin-resistant Staphylococcus aureus.

[0038] Based on the same inventive concept, the present application also claims a drug hydrogel, the raw materials of which include 1-10 parts of the zinc-doped bismuth telluride nanorod, 5-50 parts of phenyl(2,4,6-trimethylbenzoyl) lithium phosphate salt, 100-750 parts of gelatin methacrylate and 1000-7500 parts of methacryl sulfobetaine by weight.

[0039] In the present application, the hydrogel can confine the zinc-doped bismuth telluride nanorod in the gel network, avoiding the diffusion loss of the zinc-doped bismuth telluride nanorod. The hydrogel endows the patch with softness and adhesion, improving the skin fit and use comfort, while the moisturizing property and biocompatibility of the gel help the healing of the wound.

[0040] Based on the same inventive concept, the present application also claims a preparation method of the drug hydrogel, comprising the following steps:

[0041] The gelatin methacrylate, methacryl sulfobetaine and phenyl(2,4,6-trimethylbenzoyl) lithium phosphate salt are dissolved in water, the zinc-doped bismuth telluride nanorod is added, and ultraviolet light is irradiated for 10-15 s to obtain the drug hydrogel.

[0042] In one preferred embodiment, the wavelength of the ultraviolet light is 405 nm, and the power is 5-15 W.

[0043] Based on the same inventive concept, the present application also claims the use of the drug hydrogel in preparing an agent for promoting the repair of infected wounds.

[0044] Based on the same inventive concept, the present application also claims the use of the drug hydrogel in preparing an antibacterial agent.

[0045] Based on the same inventive concept, the present application also claims the use of the drug hydrogel in preparing a thermoelectric patch for promoting the repair of wounds.

[0046] Compared with the prior art, the present application has the beneficial effects that:

[0047] 1、The present application synthesizes a zinc-doped bismuth telluride nanorod, which produces ROS through a thermoelectric catalytic mechanism, and the amount of ROS produced is adjusted by controlling the temperature. Compared with the group without zinc doping (BZT-0), the conductivity of the zinc-doped bismuth telluride nanorod at room temperature is increased from ~70 S m -1 to ~111 S m -1 , and the ability to promote the generation of reactive oxygen species (ROS) is better. Compared with the BZT-0 without zinc doping, the zinc-doped bismuth telluride nanorod has a higher superoxide free radical (•O2 -) The yield was increased by 3 times. Similarly, the generated H2O2 of zinc-doped bismuth telluride nanorods was as high as 12.0 μM after 30 min of cold exposure, which was significantly higher than that of BZT-0 under the same conditions. At the same time, the zinc-doped bismuth telluride nanorods exhibited excellent antibacterial performance, and compared with the BZT-0 without zinc doping, the zinc-doped bismuth telluride nanorods reduced the viability of methicillin-resistant Staphylococcus aureus by 92.76%, and the spherical structure of methicillin-resistant Staphylococcus aureus was destroyed, and the bacterial morphology and cell membrane were no longer complete.

[0048] 2、The drug hydrogel prepared by the present application exhibits excellent mechanical properties and tissue adhesion, including excellent tensile properties (300% strain) and skin adhesion (15.8 N adhesion), and can be stably attached to the human skin even during dynamic movement of the finger joints. At the same time, the drug hydrogel of the present application has a lamellar structure and a honeycomb pore structure, and the regular and ordered pore structure and uniform pore size are beneficial to the thermoelectric catalysis of zinc-doped bismuth telluride nanorods.

[0049] 3、The drug hydrogel prepared by the present application has better anti-inflammatory performance, can induce macrophages to polarize to M2 anti-inflammatory phenotype, and the polarization rate (44.35%) of M2 macrophages induced at low temperature is significantly higher than that (18.18%) of M2 macrophages induced by interleukin 4 (IL-4) under the same conditions, and significantly reduces the secretion of IL-6 and TNF-α (pro-inflammatory factors) and increases the secretion of anti-inflammatory cytokine IL-10.

[0050] 4、The drug hydrogel prepared by the present application has excellent pro-angiogenic ability, especially under cold conditions, which can enhance the secretion of key angiogenic factors (VEGF, CD31 and CD309) at the wound site, which is 1.4 times higher than the blank group. At the same time, the drug hydrogel prepared by the present application can significantly promote the regeneration of collagen and epithelium. Within 7 days, the wound area treated by the drug hydrogel is reduced by about 80% compared with the initial wound area, and the bacterial colony of the mouse wound is reduced by more than 90%.

[0051] 5、Compared with the traditional treatment method, the BZT / SG intelligent closed-loop thermoelectric patch prepared in the present application can reduce the pain during treatment, has good biocompatibility, and has no obvious toxicity. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is a TEM image of BZT-x (x=0 / 1 / 2 / 3) nanorods, and the scale = 200 nm.

[0053] Figure 2 is an EDS spectrum of BZT-x nanorods; wherein (1) represents BZT-0, (2) represents BZT-1, (3) represents BZT-2, and (4) represents BZT-3.

[0054] Figure 3 is the diameter distribution histogram of BZT-x nanorods tested by DLS; Grouped: (1) BZT-0; (2) BZT-1; (3) BZT-2; (4) BZT-3.

[0055] Figure 4 is the X-ray diffraction pattern of BZT-x nanorods; Grouped: (1) BZT-0; (2) BZT-1; (3) BZT-2; (4) BZT-3.

[0056] Figure 5 is the X-ray photoelectron spectroscopy (XPS) characterization results of the constituent elements of BZT-x nanorods, wherein, Figure 5 A is the XPS fine spectrum of Te 3d, Figure 5 B is the XPS fine spectrum of Bi 4f, Figure 5 C is the XPS fine spectrum of Zn 2p; Grouped: (1) BZT-0; (2) BZT-1; (3) BZT-2; (4) BZT-3.

[0057] Figure 6 is the conductivity step graph of BZT-x nanorods; Grouped: (1) BZT-0; (2) BZT-1; (3) BZT-2; (4) BZT-3.

[0058] Figure 7 is the I-t and E-t curve of BZT-2 at 1.5 V / 10µA with temperature change.

[0059] Figure 8 is the electron spin resonance (ESR) spectrogram of BZT-x.

[0060] Figure 9 is the detection result graph of Amplex Red probe for BZT-x.

[0061] Figure 10 is the Mott-Schottky graph of BZT-x nanorods

[0062] Figure 11 is the ultraviolet-visible diffuse reflectance spectrum and Tauc graph of BZT-x nanorods; wherein Figure 11 A is the ultraviolet-visible diffuse reflectance spectrum of BZT-0 and BZT-2; Figure 11 B is the Tauc graph (n = 2) of BZT-0 and BZT-2 for determining the band gap; Figure 11 C is the ultraviolet-visible diffuse reflectance spectrum of BZT-1 and BZT-3; Figure 11D is the Tauc plot (n = 2) for band gap determination for BZT-1 and BZT-3.

[0063] Figure 12 A is the XPS valence band spectra of BZT-0 and BZT-2. Figure 12 A is the XPS valence band spectra of BZT-0 and BZT-2. Figure 12 B is the XPS valence band spectra of BZT-1 and BZT-3.

[0064] Figure 13 B is the comsol simulation plot of BZT-x nanorods.

[0065] Figure 14 B is the ROS production capacity of BZT-x nanorods under cold conditions; Figure 14 A is the UV-Vis absorption spectra of NBT method for determination of •O2⁻; Figure 14 B is the Amplex Red fluorescence spectra for quantification of H2O2 production; Grouping: (1) Blank control; (2) BZT-0; (3) BZT-1; (4) BZT-2; (5) BZT-3.

[0066] Figure 15 B is the ROS production capacity of BZT-x nanorods under cold conditions; Figure 15 A is the Amplex Red fluorescence spectra for H2O2 detection; 15B is the NBT UV-Vis absorption spectra for detection of •O2⁻ production; Figure 15 C is the Amplex Red fluorescence spectra; Figure 15 D is the standard curve plot of H2O2 detection kit; Grouping: (1) Blank control; (2) BZT-0; (3) BZT-1; (4) BZT-2; (5) BZT-3.

[0067] Figure 16 B is the ROS production capacity of BZT-x nanorods under cold conditions;

[0068] Figure 17 B is the ROS production capacity of BZT-x nanorods under cold conditions;

[0069] Figure 18is the SEM image of MRSA morphology after treatment, scale = 0.5 pm; Grouping: (1) blank control; (2) BZT-0; (3) BZT-1; (4) BZT-2; (5) BZT-3.

[0070] Figure 19 is the column chart of lactate dehydrogenase (LDH) release test results; Grouping: (1) blank control; (2) BZT-0; (3) BZT-1; (4) BZT-2; (5) BZT-3.

[0071] Figure 20 is the column chart of mammalian cell viability after different treatments; Grouping: (1) blank control; (2) BZT-0; (3) BZT-1; (4) BZT-2; (5) BZT-3.

[0072] Figure 21 is the rheological profile performance chart of BZT / SG hydrogel; G’ is the storage modulus; G” is the loss modulus.

[0073] Figure 22 is the SEM image of porous structure hydrogel; i in the figure is GelMA; ii is SBMA; iii is SG; iv is BZT / SG, scale = 5 pm.

[0074] Figure 23 is the characterization results of ROS generation ability of BZT / SG hydrogel during temperature change; Figure 23 A is the Amplex Red fluorescence spectrum of H2O2 generated by hydrogel under different conditions; Figure 23 B is the NBT ultraviolet-visible absorption spectrum of •O2⁻ generated by hydrogel under different conditions; Grouping: (1) control; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature.

[0075] Figure 24 is the flow cytometry chart of M1 (CD86+) and M2 (CD206+) phenotypes; Grouping: (1) LPS; (2) IL-4; (3) LPS + SG; (4) LPS + BZT / SG; (5) LPS + BZT / SG + cold temperature.

[0076] Figure 25 is the dot chart of ELISA detection of secreted cytokines: Figure 25 A is IL-6, Figure 25 B is TNF-a, Figure 25C is IL-10; Groupings: (1) LPS; (2) IL-4; (3) LPS + SG; (4) LPS + BZT / SG; (5) LPS + BZT / SG + cold temperature.

[0077] Figure 26 is the results of BZT / SG hydrogel-mediated enhancement of cell migration and pro-angiogenic activity; Figure, Figure 26 A is a scratch assay plot of HUVEC migration; Figure 26 B is a bar plot quantifying wound healing rate; Groupings: (1) blank; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature, scale = 50 pm.

[0078] Figure 27 is a dot plot of expression analysis of angiogenesis-related markers in human umbilical vein endothelial cells (HUVECs); Figure 27 A is the proportion of CD309+; Figure 27 B is the proportion of CD31+, CD309+ double positive cells; Groupings: (1) blank; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature, scale = 50 pm.

[0079] Figure 28 is the results of expression analysis of angiogenesis-related markers in human umbilical vein endothelial cells (HUVECs), Figure 28 A is a dot plot of VEGF expression density analysis; Figure 28 B is a bar plot of relative fluorescence intensity of CD31 and CD309; Figure 28 Groupings in A: (i) control; (ii) SG; (iii) BZT / SG; (iv) BZT / SG + cold temperature; Figure 28 Groupings in B: (1) blank; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature.

[0080] Figure 29 is a bar plot quantifying wound healing rate; Groupings: (1) blank; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature.

[0081] Figure 30 is a microorganism plate plot of wound healing progression, an extracellular matrix reconstituted Masson staining plot, a histological structure H&E staining plot, and an immunoreaction plot, scale = 100 pm; Groupings: (1) blank; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature.

[0082] Figure 31 is a histogram of the results of the cold analgesia evaluation; the groups are: (1) blank; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature.

[0083] Figure 32 is a comparison chart of ESR spectra of superoxide anion radicals generated by BZT-2, Comparative Example 1, and Comparative Example 2. DETAILED DESCRIPTION

[0084] The present application is not limited to the following detailed description, and those skilled in the art can implement the present application in other various embodiments according to the disclosure of the present application, or any simple changes or modifications made by using the design structure and ideas of the present application, all fall within the scope of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0085] The main materials involved in the present application are as follows:

[0086] Sodium tellurite, anhydrous bismuth chloride, methacrylic acid sulfobetaine (SBMA), and polyvinylpyrrolidone (PVP) were purchased from Shanghai Adamas Reagent Co., Ltd. Amplex red, horseradish peroxidase (HRP), methacrylated gelatin (GelMA), and phenyl (2,4,6-trimethylbenzoyl) lithium phosphate (LAP) were purchased from Xi'an Ruishi Biotechnology Co., Ltd. (Xi'an, China). Hydrazine hydrate was purchased from Chengdu Kelong Chemical Co., Ltd. Nitro blue tetrazolium chloride (NBT) was purchased from Yuanye Biomedicine Technology Co., Ltd. Live / dead cell viability assay kit, cell counting kit-8 (CCK-8), calcein-am and PI, and reactive oxygen species assay kit (DCFH-DA) were purchased from Biyun Tian Biotechnology Co., Ltd. (Shanghai, China). Methicillin-resistant Staphylococcus aureus (ATCC43300) was purchased from Shanghai Microorganism Collection and Preservation Center. BODIPY 581 / 591 C11 antibody, lactate dehydrogenase (LDH) kit, and lipoteichoic acid (LTA) ELISA kit were purchased from KKL MED Co., Ltd. (USA). Human umbilical vein endothelial cells (HUVECs) and NIH / 3T3 cells were from Xiangya Hospital, Central South University. Male BALB / c mice were purchased from Hunan Slaik Jingda Experimental Animal Co., Ltd. CD206, CD86, CD31, CD309, and VEGF antibodies were from Abeam PIc Co., Ltd. (UK). IL-6, TNF-a, and IL-10 ELISA kits were purchased from Wuhan Aiboteke Biotechnology Co., Ltd. Immunohistochemical staining and immunofluorescence kits were purchased from Wuhan Saivier Biotechnology Co., Ltd.

[0087] The main characterization methods involved in the present application are as follows:

[0088] X-ray diffraction (XRD) analysis of the samples was performed using a diffractometer from Bruker Ltd. The test conditions were: Cu Kα radiation, voltage 40 kV, current 40 mA, measurement range 5°-95°, scan speed 10° / min, step size 0.01°.

[0089] X-ray photoelectron spectroscopy (XPS) was measured by Thermo's ESCALAB Nexsa G2. The test conditions included a high vacuum environment and an Al Kα excitation source. All peaks were calibrated using Cls (284.6 eV).

[0090] The morphology of the BZT-x nanorods and wound dressings was observed using a Zeiss Sigma 500 scanning electron microscope (SEM) at an acceleration voltage of 20 kV.

[0091] Thermoelectric research methods:

[0092] To verify whether the addition of zinc can enhance the thermoelectric effect of BZT-x, 985 µL of BZT-2 (2 mg mL -1 ) in water was mixed with 15 µL of Nafion aqueous solution (15 µL mL -1 ). The mixture was dropped onto a glassy carbon electrode and dried. A three-electrode electrolytic system was used during the test, with a platinum sheet electrode as the working electrode and an Ag / AgCl electrode as the reference electrode. The electrodes were immersed in an electrolytic cell containing an aqueous solution of NaSO4 (0.1 M). The electrolytic cell was placed in a water bath at 37°C or 4°C, and data were recorded using the constant potential electrolysis current-time (I-t) measurement mode of the electrochemical workstation.

[0093] H2O2 and •O2 - The characteristic study method of generation is as follows:

[0094] BZT-x (200 µg mL -1 ) was subjected to 6 cycles (5 minutes each cycle) of temperature change between 37°C and 4°C. After centrifugation (8000 rpm), 810 µL of supernatant was collected. Subsequently, 90 µL of Amplex red (0.129 mg mL -1 ) in DMSO and 10 µL of HRP (0.500 mg mL -1 ) aqueous solution were added. The fluorescence spectrum in the range of 560-750 nm was collected with an excitation wavelength of 530 nm. For quantification, a standard curve was obtained by referring to the H2O2 solution (0-60 µM).

[0095] •O2 -The detection method was as follows: 1.00 mL of NBT (1 mg mL -1 )-containing DMSO was added to 1.00 mL of BZT-x (400 µg mL -1 )-containing DMSO. The mixture was placed in a temperature variation of 37 °C to 4 °C for 6 cycles (5 min per cycle). After centrifugation (8000 rpm), 810 µL of supernatant was collected and the UV-visible absorption spectrum was measured.

[0096] The ROS detection method was as follows: BZT / SG (0.1 g mL -1 ) was placed in a temperature variation of 37 °C to 4 °C for 6 cycles (5 min per cycle). The supernatant was aspirated and 1 M sodium hydroxide-treated DCFH-DA was added to a final concentration of 10 µM. The fluorescence spectrum in the range of 500-600 nm was collected with an excitation wavelength of 488 nm.

[0097] The band theory analysis method was as follows: measurement was performed by XPS valence band spectroscopy (Thermo Scientific K-Alpha, ThermoFisher, USA). The band gap was measured by UV-visible near-infrared diffuse reflectance absorption spectroscopy (UV-vis DRS, UV-2600, Shimadzu Instruments, Suzhou).

[0098] To determine the valence band values relative to the vacuum level, the valence band values were converted relative to the standard hydrogen electrode using the following formula: ;

[0099] where φ represents the instrument work function.

[0100] In addition, the band gap obtained from the UV-visible near-infrared diffuse reflectance absorption spectrum must be converted to a Tauc plot using the following formula: ;

[0101] where α is the absorption coefficient, h is the Planck constant, v is the frequency, A is the proportionality constant, hν is the photon energy, and Eg is the semiconductor band gap. The exponent n depends on the type of semiconductor: n = 1 / 2 for direct semiconductors and n = 2 for indirect semiconductors. The exponent n can be determined by fitting the Schottky curve.

[0102] Mott-Schottky analysis: using a three-electrode system, a 0.1 M NaSO4 solution was used as the electrolyte, the frequency was 500 Hz, and the measurement range was set to start from the open circuit voltage ± 0.6 V. UV-visible diffuse reflectance spectroscopy was measured using a UV-visible spectrophotometer (UV-2600, Shimadzu Instruments, Japan).

[0103] The test method for in vitro bactericidal ability was as follows: MRSA cells (108 CFU mL -1 ) incubated with BZT-x (200 pg mL -1 ) and then temperature cycled between 37 °C and 4 °C for 6 cycles (5 min per cycle). Subsequently, the bacteria from each group were collected and colony counts were performed. After extraction of LDH (lactate dehydrogenase) and LTA (lipoteichoic acid) using the bacterial treatment method described above, the subsequent procedures were performed according to the instructions provided in the kit.

[0104] The method for SEM observation of bacterial morphology was as follows: MRSA (10 -1 CFU mL 8 ) was treated with BZT-x nanorods (200 pg mL -1 ) according to the procedure described above. The bacteria were fixed with glutaraldehyde overnight at 4 °C, dehydrated in ethanol in a gradient (10%, 30%, 50%, 70%, 90%), and then observed under SEM.

[0105] The method for macrophage polarization analysis was as follows: J774A.1 macrophages (1 x 10 6 cell mL -1 , 2 mL) were seeded in 6-well plates. Macrophage polarization was induced with LPS (1 pg mL -1 ) and IL-4 (25 ng mL -1 ) in DMEM medium for 24 h. Blank hydrogels or BZT / SG were added to the wells and temperature cycled between 37 °C and 4 °C for 6 cycles (5 min per cycle). After removal of the hydrogels, the macrophages were incubated for an additional 6 h, detached with 1 mM EDTA solution, centrifuged at 3000 rpm for 3 min, and then fixed with paraformaldehyde for 15 min. The macrophages were permeabilized with 0.5% Triton X-100 for 10 min and blocked with 2% BSA for 30 min to eliminate non-specific adsorption. The macrophages were then incubated with FITC-labeled CD206 antibody and APC-labeled CD86 antibody at 4 °C for 12 h. After overnight staining, the cells were washed with phosphate-buffered saline (PBS) 3 times. Macrophage polarization was analyzed by flow cytometry (NovoCyte, Agilent, USA).

[0106] The method for HUVECs growth and differentiation behavior analysis was as follows: HUVECs cells were seeded at 1 x 10 6Cells were seeded in 6-well plates at a density of 1 x 105cells per well and incubated at 37 °C, 5% CO2. When the cells grew to about 90%, 10 μL of special pipette tip was used to scratch directly in each well. Then treated with SG or BZT / SG and temperature cycled between 37 °C to 4 °C for 6 times (5 min for each cycle). After incubation for 24 h, cell images were taken using a fluorescence inverted microscope (IX-83, Olympus, Japan). To investigate the effect of HUVECs on angiogenesis, the present application cultured HUVEC cells in DMEM medium supplemented with 10% fetal bovine serum (FBS). The same hydrogel treatment and temperature cycling protocol was used. After incubation for 24 h, cells were observed under an inverted microscope. According to the manufacturer's instructions, cells were stained with PerCP-conjugated CD309 and FITC-conjugated CD31 antibodies. The expression levels of growth factors CD31 and CD309 in HUVECs were detected by flow cytometry and laser scanning confocal microscopy (FV3000, OLYMPUS, Japan).

[0107] The method of Western blotting is as follows: the treated HUVECs cells were lysed with 100 μL RIPA buffer and incubated at 4 °C for 10 min. Subsequently, the lysate was centrifuged, the supernatant was discarded, and the remaining protein sample was mixed with loading buffer at an appropriate ratio and then boiled at 100 °C for 10 min. A 12% preformed TBE PAGE gel (Bi Yun Tian Biotechnology, Shanghai, China) was used. The samples were loaded onto the gel, initially run at 80 V for 30 min, then at 100 V for 60 min, and transferred (at 20 V for 60 min). At room temperature, 5% (w / v) BSA prepared in TBST buffer was blocked for 1 h on a constant shaker. VEGF and β-actin antibodies were diluted with 0.5% BSA solution. After removing the blocking solution, the membrane was incubated with the primary antibody at 4 °C overnight. After incubation, the membrane was washed with TBST for 3 times, 5 min each time, and the excess primary antibody was removed. Then, HRP-labeled goat anti-rabbit / mouse antibody was added, diluted with 0.5% BSA, and incubated at room temperature for 1 h. After incubation with the secondary antibody, the membrane was washed with TBST for 3 times, 5 min each time. Finally, the bands were visualized using ECL detection reagent (Bi Yun Tian Biotechnology, Shanghai). All antibodies, including the primary antibody, the secondary antibody, and the HRP-labeled goat anti-rabbit / mouse antibody, were purchased from Bi Yun Tian Biotechnology, Shanghai, China.

[0108] The method for testing biocompatibility in vitro is as follows: HUVECs and NIH / 3T3 cells were seeded in 96-well plates at a density of 1 x 105cells per well. 4 Each well was added with hydrogel extract solution (0.1 mg mL -1Cells were cultured in DMEM medium with 10% FBS for 24 h. Cell viability was assessed using a CCK-8 kit according to the manufacturer's instructions, with 3 replicates per group. In addition, cells were stained with calcein-AM (10 mM) and PI (10 mM) for 30 min and observed using a laser scanning confocal microscope.

[0109] The method for evaluating wound healing in mice is as follows: All animal experiments were performed at the Experimental Animal Center of Xiangya Medical College, Central South University (Changsha, China), in strict compliance with the approved experimental protocols and ethical guidelines (No. XMSB-2024-0038). Male BALB / c mice were shaved and disinfected on the back before being anesthetized by intraperitoneal injection of a sodium pentobarbital solution (50 mg kg -1 ). A sterile biopsy punch was used to create a 6-mm-diameter circular full-thickness skin wound on the back of each mouse. Each wound was inoculated with 50 µL of an MRSA bacterial suspension (10 8 CFU mL -1 ). After 24 h, the mice were randomly divided into 5 groups: (1) Blank (2) SG: (3) SG + cold temperature: (4) BZT / SG; (5) BZT / SG + cold temperature. All mice received continuous treatment for 3 days. Wound images were taken on day 0, day 1, day 2, day 3, day 5, and day 6. The body weight of the mice was recorded throughout the experiment. On day 6, the wound tissue was collected and placed in sterile PBS. Subsequently, 50 µL of the PBS solution was spread on an agar plate for colony counting.

[0110] The method for analyzing in vivo growth and differentiation behavior is as follows: Wound tissue was collected on day 6 and fixed with 4% paraformaldehyde. After paraffin embedding and sectioning, the sections were stained with hematoxylin and eosin (H&E) and Masson's trichrome for histological analysis. Immunofluorescence staining was performed according to the manufacturer's instructions to evaluate the expression of inflammatory markers (CD86 and CD206) and angiogenesis markers (CD31) in the wound tissue.

[0111] The method for evaluating in vivo biocompatibility is as follows: To evaluate the in vivo biological safety of the wound dressing, the heart, liver, spleen, lung, and kidney of the mice in each group were taken at the end of treatment for histological examination by H&E staining.

[0112] All data are presented as mean ± SD (n = 3); **p < 0.01, ***p < 0.001.

[0113] Example 1

[0114] Synthesis of Bi2Te3 nanorods doped with different concentrations of zinc (Zn)

[0115] The samples were named as BZT-x, where "x" represents the Zn doping level determined by inductively coupled plasma (ICP) analysis: BZT-0 (undoped), BZT-1 (0.106 mol%), BZT-2 (0.194 mol%) and BZT-3 (0.302 mol%).

[0116] In a three-neck flask, sodium tellurite (0.116 g), sodium hydroxide (0.200 g), polyvinylpyrrolidone PVP (0.100 g) and ethylene glycol (20.00 mL) were added, after stirring at 150 °C, 1.00 mL of hydrazine hydrate was added, and the reaction was allowed to proceed for 1 h; then bismuth chloride (0.110 g) dissolved in 20.00 mL of ethylene glycol was added, and the reaction was allowed to proceed for another 1 h. Subsequently, 1.00 mL of hydrazine hydrate and different concentrations of zinc chloride (5 / 10 / 15 mg) dissolved in 5.00 mL of ethylene glycol were added, and the reaction was allowed to proceed for 1 h before cooling and precipitation with 80.00 mL of acetone to obtain the final product. The final product was washed and vacuum dried to obtain BZT-x (x = 0 / 1 / 2 / 3) nanorods.

[0117] The BZT-x (x = 0 / 1 / 2 / 3) nanorods were characterized, and the results of TEM characterization are shown in Figure 1 , which show that all BZT-x (undoped with zinc and doped with 0.194 mol% zinc) exhibit the morphology of elongated nanorods (scale = 200 nm). EDS spectrum testing was performed, and the results are shown in Figure 2 , where (1) represents BZT-0, (2) represents BZT-1, (3) represents BZT-2, and (4) represents BZT-3, which show that Bi, Te, and Zn elements are detected in (2)-(4).

[0118] Dynamic light scattering (DLS) analysis was performed, and the results are shown in Figure 3 , which show that after Zn doping, the size of BZT-x nanorods is shortened to below 200 nm. With the increase of zinc content, the average length of the nanorods gradually decreases from about 290 nm (BZT-0) to about 170 nm (BZT-3). This reduction indicates that Zn doping significantly affects the crystal growth of BZT-x, allowing it to be redirected and modified.

[0119] X-ray diffraction (XRD) was performed, and the results are shown in Figure 4As shown, the results indicate that the standard diffraction patterns of BZT-x and BiTe (JCPDS# 15-082633) are in good agreement. Notably, the intensity of the (0 1 11) peak at 40.3° increases with increasing zinc content, indicating that Zn doping preferentially affects this crystal plane. To understand this structural modification, DFT simulations were performed on the (0 1 11) surface. The results show that BZT-x exhibits a coordination mode similar to BZT-0, with some Bi atoms being replaced by Zn atoms, consistent with the changes observed by XRD.

[0120] The chemical states of each constituent element were characterized by X-ray photoelectron spectroscopy (XPS), and the results are as follows: Figure 5 As shown, where, Figure 5 A is the XPS fine spectrum of Te 3d. Figure 5 B represents the fine XPS spectrum of Bi4f. Figure 5 C represents the XPS fine spectrum of Zn 2p. The results show that for BZT-x, the valences of Bi and Te are +3 and -2, respectively. With increasing Zn doping concentration, the binding energy between Bi and Te gradually decreases, while the peak intensity of the Zn 2p orbital at 1020.8 eV increases. These observations collectively demonstrate charge redistribution through Zn-Te electron transfer, confirming the establishment of covalent bonds between the dopant (Zn) and the matrix (Bi / Te).

[0121] The conductivity of BZT-x at room temperature (300 K) was tested, and the results are as follows: Figure 6 As shown, the results indicate that in zinc-doped Bi₂Te₃, Zn 2+ Replace Bi 3+ The primary cause is charge compensation by Bi vacancies. Compared to undoped BZT-0, these vacancies result in a more negative zeta potential for BZT-x. The presence of Bi vacancies also increases the carrier concentration. Therefore, after doping BZT with zinc, the conductivity of BZT-x at room temperature (300 K) increases from ~70 S m. -1 Increased to ~111 S m -1 .

[0122] like Figure 7 As shown, under controlled temperature changes, constant voltage (1.5 V) and constant current (10 µA) conditions, BZT-2 generates measurable thermocurrent (~9 µA) and voltage (~0.5 V).

[0123] The thermoelectric properties of BZT-x endow it with cold catalytic activity for redox reactions. To verify this, electron spin resonance (ESR) spectroscopy analysis was performed on BZT-x using 5,5-dimethyl-1-pyrrolline-N-oxide (DMPO). The six-line spectrum revealed typical (intensity ratio 3:3:2:3:2:3) superoxide radicals (•O2). - ) Formation, such as Figure 8 As shown. This spectral feature arises from hyperfine coupling with two equivalent nitrogen nuclei, confirming the presence of •O2. - The generation of [the substance / method] was observed. The detection results of the Amplex Red probe (Aladdin reagent, CAS: 119171-73-2) are as follows: Figure 9 As shown, the results revealed the detection of another type of ROS, H2O2. The significant oxidation of Amplex Red indicates that the cold catalytic process of BZT-x produced H2O2.

[0124] To elucidate the cold catalysis mechanism, this invention systematically investigated the band structure of BZT-x. Mott-Schottky analysis confirmed the p-type semiconductor characteristics of BZT-x, with a positive slope (…). Figure 10 (A and 10B). The UV-Vis absorption spectra were converted into Tauc plots with an exponent n = 2; the results are as follows... Figure 11 As shown in A, 11B, 11C, and 11D, the band gap energies are 1.92 eV (BZT-0), 1.96 eV (BZT-1), 1.75 eV (BZT-2), and 2.12 eV (BZT-3). XPS valence band spectra ( Figure 12 A and Figure 13 B) shows that the valence band positions relative to vacuum are 1.08 eV and 0.58 eV, corresponding to 0.84 V and 0.34 V for the standard hydrogen electrode (SHE). Therefore, the conduction bands of BZT-0 and BZT-2 relative to SHE are calculated to be -1.08 V and -1.41 V, respectively, the conduction band of BZT-1 is -1.62 V, and the conduction band of BZT-3 is -1.18 V.

[0125] COMSOL thermoelectric potential distribution simulation was performed on BZT-x, and the results are as follows: Figure 14 As shown in the figure. The results show that the potential of BZT-2 (1.03 V) is 7 orders of magnitude higher than that of undoped BZT-0. This significant enhancement stems from the fact that zinc doping optimizes carrier dynamics through multiple mechanisms. First, the zinc dopant introduces additional carriers, reduces recombination centers, and enhances carrier mobility, thereby promoting efficient electron-hole separation. Second, the thermal gradient induces valence band tilt, guiding hole transport towards the hot end. Compared to BZT-0, its conductivity is improved by 30%. Zinc doping introduces additional holes, while increasing carrier concentration and reducing the Seebeck coefficient, its Fermi level (εF ) located near the valence band maximum. The synergistic effects of a narrower band gap, thermal gradient-induced valence band tilting, and accelerated carrier migration acceleration collectively enhance ROS production in thermoelectric catalysis. Excessive doping and high zinc loading of BZT-3 failed to produce further band structure improvement. These results show that BZT-2 represents an ideal balance of zinc doping concentration, maximizing catalytic efficiency while maintaining good electronic performance of the BZT system.

[0126] Meanwhile, the ROS production capacity of BZT-x nanorods under cold conditions was quantitatively compared by ultraviolet-visible absorption spectrum and Amplex Red fluorescence emission spectrum of •O2⁻ measured by NBT method, and the results are shown in Figure 14 A and Figure 15 B. Compared with undoped BZT-0, the •O2⁻ yield of BZT-2 increased by 3 times, which is consistent with the trend of its thermoelectric performance.

[0127] Similarly, the ROS production capacity of BZT-x nanorods under cold conditions was quantitatively compared by ultraviolet-visible absorption spectrum and Amplex Red fluorescence emission spectrum of •O2⁻ measured by NBT method, and the results are shown in Figure 15 A, Figure 15 B, Figure 15 C, Figure 16 D. The results show that BZT-2 (200 μg mL-1) produces H2O2 up to 12.0 μM, which is significantly higher than 7.6 μM produced by BZT-0 under the same conditions. The response of ROS production to temperature change is as small as 0.5℃, which is crucial for clinical application.

[0128] Under low temperature conditions, BZT nanorods can produce •O2⁻ and H2O2, thereby jointly inducing oxidative damage to MRSA. To further quantify this effect, the present application systematically evaluates the antibacterial effect of BZT-x on MRSA. As expected, all samples exhibit antibacterial activity against MRSA under low temperature conditions (p < 0.05) Figure 17 , grouped as: (1) control; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature). Notably, BZT-2 exhibits the highest efficacy, reducing the viability of MRSA by 92.76% (p < 0.05) Figure 18 ) after six cycles of low temperature changes (37 ℃ ± 4℃), which is consistent with the optimal ROS production capacity of BZT-2. SEM analysis shows that the structure of MRSA treated by BZT-2 gradually deteriorates, including the loss of spherical morphology (p < 0.05) Figure 19). The principle of live / dead staining is that dead bacteria will be marked by iodine propyl (PI) penetrating the cell membrane and showing red fluorescence. After BZT-2 treatment at low temperature, almost all bacteria were dead and stained by iodine propyl (PI), showing a large amount of red fluorescence, i.e. a large number of bacteria died. In addition, the lactate dehydrogenase (LDH) release test further confirmed the membrane damage after MRSA treatment Figure 20 ). Importantly, BZT-x showed minimal cytotoxicity to mammalian cells (HUVECs and NIH / 3T3), maintaining high viability (>90%) even after six low-temperature cycles Figure 32 ). Mechanistic studies showed that the selective targeting ability mainly originated from two key factors. First, BZT-x specifically targeted LTA, a polysaccharide on the surface of gram-positive bacteria, and the binding capacity of BZT-2 was 4.8 mg / g, and the binding capacity of the rest of the groups was significantly lower than that of BZT-2. Second, low temperature was conducive to the coordination of BZT-x with phosphate on LTA, further enhancing their binding. In addition, the difference in ROS tolerance between bacteria and mammalian cells played a crucial role. Mammalian cells can maintain redox homeostasis through a powerful antioxidant defense system, including superoxide dismutase, catalase, and glutathione peroxidase, but MRSA lacks a similar ROS scavenging system. This difference makes MRSA particularly sensitive to BZT-x-induced lipid peroxidation at low temperature. In summary, BZT-x selectively targets MRSA through coordination-mediated phosphote binding and cold-triggered ROS production, while being non-toxic to mammalian cells, i.e. the newly synthesized BZT-x exerts bactericidal effects while having no significant damage to beneficial normal cells.

[0129] Comparative Example 1

[0130] According to the same molar ratio as zinc chloride (10 mg), zinc chloride was replaced by anhydrous cuprous chloride to prepare copper-doped nanorods.

[0131] Comparative Example 2

[0132] According to the same molar ratio as zinc chloride (10 mg), zinc chloride was replaced by zinc oxide to prepare zinc oxide-doped nanorods.

[0133] The nanorods of Comparative Example 1 and Comparative Example 2 were also subjected to electron spin resonance (ESR) spectral analysis using 5,5-dimethyl-1-pyrroline-n-oxide (DMPO) as a spin trapping agent to observe the formation of superoxide free radicals (•O2 - ), and the results are shown in Figure 21The results show that BZT-2, Comparative Example 1 and Comparative Example 2 can all produce superoxide anions, but the amount of superoxide anions produced by BZT-2 is 2.3 times and 4.7 times that of the nanorods of Comparative Example 1 and Comparative Example 2, respectively, indicating that BZT-2 has a significant advantage in superoxide anion production efficiency. At the same time, the potential of BZT-2 (1.03 V) is 2 and 4 orders of magnitude higher than that of the nanorods of Comparative Example 1 and Comparative Example 2, respectively.

[0134] At the same time, the ROS production capacity of the nanorods under cold conditions was quantitatively compared, and the results showed that the response of the nanorods of Comparative Example 1 and Comparative Example 2 to temperature change was about 2.0°C and 5.0°C, respectively, and the temperature sensitivity was not high.

[0135] Example 2

[0136] Preparation of BZT / SG (zinc-doped Bi2T3 nanorod thermoelectric hydrogel)

[0137] A flexible hydrogel was prepared using gelatin methacrylate (GelMA) and methacrylsulfobetaine (SBMA) as raw materials for wound dressings, giving it good adhesion on the wound surface, excellent mechanical properties, and water absorption. In the present invention, BZT-2 (0.194 mol%) is incorporated into the hydrogel to form a BZT / SG composite material, and the specific operation is as follows:

[0138] GelMA (0.125 g), SBMA (1.250 g), and phenyl (2,4,6-trimethylbenzoyl) lithium phosphate salt LAP (0.005 g) were dissolved in 0.50 mL of water. Then, BZT-2 nanorods (0.001 g) were added to 0.50 mL of water. Irradiation with 405 nm light (power 5 W) for 10 s resulted in a BZT / SG hydrogel.

[0139] The BZT / SG hydrogel exhibits excellent tissue adhesion and can maintain stable adhesion to human skin even during dynamic movement of the finger joint. This strong adhesion is due to a variety of interfacial interactions, including hydrogen bonding and cationic π-π interactions between the functional groups of the hydrogel (i.e., hydroxyl, amino, and thiol groups) and the skin tissue. Notably, the hydrogel maintains structural integrity after repeated twisting tests, showing superior toughness. Mechanical characterization shows that the performance of the composite system is enhanced, with both the storage modulus (G') and the loss modulus (G') exceeding those of the single-component gel Figure 22 ), indicating that the mechanical strength and viscoelasticity are improved through component synergy. The BZT / SG hydrogel exhibits excellent mechanical properties, including excellent tensile properties (300% strain) and strong skin adhesion (15.8 N adhesion).

[0140] The combination of SBMA and GelMA can significantly increase the viscosity of the gel while maintaining good swelling properties. Specifically, the hydrogel can absorb more than 8 times its weight of water while maintaining a swelling of less than 800%, showing a balanced absorption capacity, superior to most reported hydrogels (Table 1).

[0141] (1) Rinaudo, M. Chitin and Chitosan: Properties and Applications. Prog. Polym. Sci. 2006, 31, 603-632.

[0142] (2) Collins, M. N.; Birkinshaw, C. Hyaluronic Acid Based Scaffolds for Tissue Engineering—a Review. Carbohydr. Polym. 2013, 92, 1262-1279.

[0143] (3) Lee, K. Y.; Mooney, D. J. Alginate: Properties and Biomedical Applications. Prog. Polym. Sci. 2012, 37, 106-126.

[0144] (4) Zhu, T.; Jiang, C.; Wang, M.; Zhu, C.; Zhao, N.; Xu, J. Skin-Inspired Double-Hydrophobic-Coating Encapsulated Hydrogels with Enhanced Water Retention Capacity. Adv. Funct. Mater. 2021, 31, 2102433.

[0145] (5) Zhu, J. Bioactive Modification of Poly(Ethylene Glycol) Hydrogels for Tissue Engineering. Biomaterials 2010, 31, 4639-4656.

[0146] (6)Haraguchi, K.; Takehisa, T. Nanocomposite Hydrogels: A UniqueOrganic–Inorganic Network Structure with Extraordinary Mechanical, Optical, and Swelling / De-Swelling Properties. Adv. Mater. 2002, 14, 1120-1124.

[0147] This superior swelling and adsorption capacity effectively absorbs wound exudate. (From SEM images...) Figure 23 In the figure (i = GelMA; ii = SBMA; iii = SG; iv = BZT / SG, scale bar = 5µm), it can be seen that the SG hydrogel combines the layered structure of GelMA hydrogel and the honeycomb pore structure of SBMA hydrogel. The regular and ordered pore structure and uniform pore size are beneficial to the thermoelectric catalysis of BZT nanorods. COMSOL thermal conductivity simulation shows that cold stimulation induces heat transfer between the hydrogel and the skin, establishing a continuous temperature gradient and continuously activating the thermoelectric effect of BZT-2. The BZT / SG hydrogel maintains sufficient ROS generation during temperature changes (… Figure 23 A and Figure 24 B, grouped as follows: (1) control; (2) SG; (3) SG + cold temperature; (4) BZT / SG; (5) BZT / SG + cold temperature), further confirming its cold-triggered thermoelectric activity.

[0148] The BZT / SG hydrogel of this invention exhibits superior anti-inflammatory properties, inducing macrophage polarization towards the M2 anti-inflammatory phenotype. Macrophages were pretreated with lipopolysaccharide (LPS) to polarize them into M1 macrophages. Flow cytometry was used to analyze changes in macrophage polarization induced by the BZT / SG hydrogel. For comparison, interleukin-4 (IL-4) was used as a control. Under low-temperature conditions, the proportion of M1 macrophages (CD86+) decreased to 3.34%. Figure 25 The proportion of M2 macrophages (CD206+) increased to 44.35%. The polarization rate of M2 macrophages induced by BZT / SG at low temperature (44.35%) was higher than that induced by IL-4 (18.18%). Furthermore, BZT / SG treatment at low temperature significantly reduced the secretion of IL-6 and TNF-α, decreasing them by 82.20% (…). Figure 25 A) and 81.50% Figure 25 B). Simultaneously, the secretion of the typical anti-inflammatory cytokine IL-10 increased by 125.25% ( Figure 26C). Therefore, BZT / SG combined with low temperature therapy can effectively induce macrophages to polarize to anti-inflammatory M2 phenotype.

[0149] To elucidate the mechanism of BZT / SG-induced macrophage polarization under cold exposure, the present application conducted transcriptomic analysis. Principal component analysis (PCA) showed that there was a clear separation between the control group and the BZT / SG + cold temperature group, with high intra-group sample consistency and good experimental reproducibility. After BZT / SG + cold treatment for 30 minutes, significant changes in gene expression were observed. M1-related markers (such as HSPA1B, C1QTNF1, SLCs, CCN1) were down-regulated, while M2-related markers (such as APOE, SPP1, ZDHHC12, CUEDC2) and metabolic regulators (such as AKR1B, CDK5) were up-regulated. Pathway analysis using KEGG and GSEA found enrichment of key metabolic processes and signaling pathways, including fatty acid degradation, carbohydrate metabolism, MAPK, and mTOR signaling pathways. These results suggest that BZT / SG + cold temperature regulates macrophage polarization through ROS signaling and metabolic reprogramming.

[0150] Through scratch test and tube formation test, the present application systematically evaluated the pro-angiogenic ability of BZT / SG wound dressing. In the scratch test, BZT / SG treatment under cold stimulation significantly enhanced HUVEC migration, with a scratch healing rate of 99.07% (p < 0.001) compared to the control group. Figure 26 A and Figure 27 B). Cold-treated cells showed close intercellular arrangement of spindle or star shape after 30 minutes of stimulation, confirming the strong pro-migration ability of the synthesized novel BZT / SG. Tube-like structures were evaluated by analyzing three randomly selected microscopic fields for each experimental group, with both tube-like structures and cell nodes manually counted using ImageJ software. Statistics showed that the control group had an average of 5 tubes, while the BZT / SG and BZT / SG + cold treatment groups had 16 and 52 tubes, respectively. Similarly, in the BZT / SG + cold treatment group, the number of nodes increased from 8 in the control group to 122.

[0151] Immunofluorescence analysis showed that CD309 expression was up-regulated by 52.71% (p < 0.001) in BZT / SG-treated cells under low temperature conditions compared to the blank control. Figure 27 A). In addition, in the BZT / SG + cold temperature group, CD31 + CD309 + The proportion of cells increased to 20%, an increase of 1.4 times compared to the blank group (p < 0.001). Figure 28 B). These findings suggest that BZT / SG wound dressing, especially under low temperature conditions, can better secrete key angiogenic factors (VEGF, CD31 and CD309) at the wound site (A and Figure 28 A and Figure 29B). The results of Western blot analysis showed that the blank group had the lowest VEGF expression, while the BZT / SG + cold temperature group was significantly up-regulated. ImageJ software density analysis showed that the VEGF expression of the BZT / SG + cold temperature group was more than 3 times higher than that of the blank group. COMSOL simulation confirmed that the BZT nanorods generated a thermoelectric field with a strength of 1500 V / m under cold stimulation. Electrical stimulation has an up-regulating effect on VEGF expression. These results strongly suggest that the thermoelectric field generated by BZT nanorods promotes angiogenesis mainly through electrical stimulation of VEGF secretion, ultimately accelerating wound healing.

[0152] Example 3

[0153] Preparation and testing of flexible patch

[0154] The present application developed five functional components of the flexible patch electronic platform: (1) wound sensing module with dual temperature sensors, (2) active temperature regulation module, (3) rechargeable power supply, (4) OLED real-time display interface, (5) wireless data transmission / control module. The wound sensing module uses dual high-precision temperature sensors to continuously monitor the temperature difference (AT) between the wound site and the adjacent healthy tissue. For active thermal management, the temperature regulation module uses a thermoelectric cooling device that can accurately control the temperature of the wound dressing.

[0155] The data transmission and control module includes a microcontroller for data acquisition and processing, and all data are transmitted wirelessly to the phone through Bluetooth for real-time monitoring and adjustment. The power supply consists of a small rechargeable lithium-ion battery. Key operating parameters, including real-time wound temperature, AT, applied voltage, and remaining operating time, will be displayed on the OLED screen.

[0156] The working voltage, response temperature, and manual control functions can be remotely adjusted through the mobile phone application, and a closed-loop control mechanism is adopted to automatically activate the treatment program when the AT exceeds the 0.5℃ threshold. This activation is visualized through LED indicator lights and real-time OLED parameters. Once the predetermined operating time is reached, the system re-evaluates the AT to determine whether additional cooling is needed, thus maintaining adaptive closed-loop control through cyclical intervention and evaluation.

[0157] The temperature can be accurately controlled by applying a square wave voltage. COMSOL Multiphysics software was used to simulate the temperature distribution within the skin tissue. When the temperature of the cooler was set to 4-37℃, the local temperature at a tissue depth of 10 mm decreased by about 21℃ (from 31℃ to 9.8℃) within 5 minutes, and then recovered again after 5 minutes. The simulation results show that the closed-loop thermal management system can effectively achieve rapid cold temperature regulation, which is beneficial for subsequent thermoelectric therapy.

[0158] The flexible patch electronic platform structure of the present application is essentially the same as the intervention device for remote intelligent control of Bi2Fe4O9nanospheres (Zou Y, Jin B, Li H, Wu X, Liu Y, Zhao H, Zhong D, Wang L, Chen W, Wen M, Liu YN. Cold Nanozyme for Precise Enzymatic Antitumor Immunity. ACS Nano. 2022 Dec 27;16(12):21491-21504. doi: 10.1021 / acsnano.2c10057. Epub 2022 Dec 1. PMID: 36453617). The difference is that BZT nanorods are used instead of Bi2Fe4O9nanospheres.

[0159] The present application uses a flexible patch to conduct in vivo experiments to evaluate the therapeutic effect of BZT / SG on wound healing under MRSA infection. A wound model with a diameter of 6 mm is constructed, and each wound is inoculated with 50 µL of MRSA bacterial suspension (10 8 CFU mL -1 ). The mice are randomly divided into 5 groups: (1) blank control, (2) SG, (3) SG + cold temperature, (4) BZT / SG and (5) BZT / SG + cold temperature. Each group of mice is given medication every day for 3 consecutive days. On day 0, day 1, day 2, day 3, day 5 and day 6, wound images are taken. The results are shown in Figure 29 . The results show that after 7 days, the control group has obvious pus formation, and there is severe bacterial infection. In contrast, the BZT / SG + cold temperature group has obvious inhibition of pus on the 3rd day, and thereafter the wound gradually enters the healing stage. Within 7 days, the wound area of the BZT / SG + cold treatment group is reduced by about 80% compared to the initial wound area (p < 0.001). Figure 30 On day 7, mouse wound skin tissue cultures are taken for colony counting. Compared with the untreated control group, BZT / SG + cold treatment results in a more than 90% reduction in mouse wound bacterial colonies. Masson staining and H&E staining are used for histological examination of the wound tissue of each group. For untreated mice, wound tissue shows extensive inflammatory cell infiltration and incomplete epidermis formation. In contrast, BZT / SG + cold-treated wounds show the best features of tissue regeneration, including good collagen deposition (36.2 ± 0.36%) and complete epidermal repair, with a thickness of more than 140Hm (p < 0.001). Figure 31). Well-organized hair follicle neogenesis was observed in the dermis, indicating successful progression of wound repair from the inflammatory to the proliferative phase. Although BZT / SG treatment alone also promoted epidermal and hair follicle regeneration, incomplete tissue repair was still observed under the microscope. Immunohistochemical analysis showed that the formation of CD31 -positive capillary networks and arterioles in the BZT / SG + cold temperature group demonstrated enhanced neovascularization. Immunofluorescence staining showed that the CD206+ / CD86+ ratio increased by 3.2 times compared to the control group, indicating significant polarization of M2 macrophages.

[0160] To evaluate the analgesic potential of the treatment system, the present invention established a standardized pain assessment model by creating a wound on the back of the hind paw of a mouse. Pain sensitivity was quantified using a calibrated Von Frey filament applied to the area surrounding the wound. The mechanical pain threshold was determined by measuring the minimum bending force required to cause paw withdrawal, with higher values indicating more pronounced analgesia. BZT / SG combined with cold therapy showed superior analgesic effects, reaching a maximum threshold of 4.4 g, while the untreated control group was 1.5 g (p < 0.001). ​ These results confirm that BZT / SG has a significant analgesic effect when used in combination with cold. These findings collectively indicate that thermoelectrically regulated BZT / SG treatment provides multiple therapeutic effects, including enhanced antibacterial properties, tissue regeneration, and outstanding analgesic effects.

[0161] Meanwhile, the present invention evaluated the in vitro biocompatibility of the BZT / SG patch according to the ISO 10993-1:2018 guidelines. After culturing NIH / 3T3 and HUVECs cells in different concentrations of BZT / SG hydrogel leachate for 24 hours, the cell viability remained above 80%, meeting the cytotoxicity standards specified in ISO 10993-1:2018. Live / dead cell staining further showed that there were very few dead cells after BZT / SG hydrogel treatment. Other viability tests conducted under different treatment conditions yielded consistent results, indicating that the BZT / SG patch has excellent cell compatibility.

[0162] Biological safety was further investigated through in vivo studies. There were no statistically significant changes in body weight in different treatment groups. Histopathological examination of major organs (heart, liver, spleen, lung, and kidney) on day 7 after treatment found no signs of tissue damage, inflammatory infiltration, or other pathological abnormalities. These results confirm that the BZT / SG patch has good biological safety.

[0163] In summary, the present application proposes a closed-loop thermoelectric patch that integrates real-time wound monitoring and comprehensive treatment functions. The intelligent patch combines thermoelectric hydrogel with a closed-loop temperature control module and can be wirelessly operated through a smartphone. Dual temperature sensors accurately track the temperature of the wound site and surrounding tissues. When a temperature difference of more than 0.5℃ is detected, indicating inflammation, the treatment is automatically started. After activation, the patch provides precisely controlled square wave voltage, using engineered BZT-x nanorods to initiate thermoelectric therapy. These materials generate therapeutic ROS, mainly •O2⁻ and H2O2. By targeting oxidative stress, MRSA is eliminated and anti-inflammatory macrophage polarization is induced. The thermoelectric process simultaneously generates thermal current, stimulating cell proliferation and accelerating angiogenesis at the wound site. During treatment, the cooling effect produced in situ significantly relieves pain. Animal studies show that wound healing rate is increased by 80% compared with the control group, collagen deposition is enhanced in preclinical models, and epithelial cell regeneration is complete. The patch ensures excellent biocompatibility and strong mechanical durability, while its flexible design provides comfortable wear and reliable adhesion during exercise. This autonomous closed-loop system controlled by a smartphone represents a major advance in wound treatment and care technology, setting a model for personalized therapy. At the same time, it shows the potential for clinical and home portable use, which can be applied to chronic wounds such as diabetic ulcers, burns, etc. The synergistic integration of thermoelectric catalysis and digital intelligent control realizes a new breakthrough in wound treatment, laying the foundation for the next generation of closed-loop therapy systems. The fusion of advanced functional materials and bioelectronic elements sets a new standard for automated medical devices.

[0164] It should be noted that the above examples are merely examples for clearly illustrating the present application, and are not intended to limit the implementation modes of the present application. Based on the above description, other different forms of changes or modifications can be made by those skilled in the art. It is impossible to enumerate all the implementation modes here. Any obvious changes or modifications derived from the technical solutions of the present application are still within the scope of protection of the present application.

Claims

1. A zinc-doped bismuth telluride nanorod, characterized in that, in, The molar ratio of Bi, Zn, and Te is 0.85~0.95:0.05~0.15:1.

5.

2. The zinc-doped bismuth telluride nanorod according to claim 1, characterized in that, The molar ratio of Bi, Zn, and Te is 0.88~0.92:0.08~0.12:1.

5.

3. The method for preparing zinc-doped bismuth telluride nanorods according to claim 1 or 2, characterized in that, Includes the following steps: The tellurium source, alkali, surfactant, solvent, and reducing agent are reacted at 150-155℃ in a first stage reaction; then a bismuth source is added and a second stage reaction is carried out at 150-155℃; finally, a reducing agent and a zinc source are added and a third stage reaction is carried out at 150-155℃ to precipitate the zinc-doped bismuth telluride nanorods; the molar ratio of Te in the tellurium source, Bi in the bismuth source, and Zn in the zinc source is 0.85~0.95:0.05~0.15:1.

5.

4. The preparation method according to claim 3, characterized in that, The tellurium source is one or more of the following: oxyacid salts of tellurium, metallic tellurium, or tellurides; the alkali is at least one of sodium hydroxide and potassium hydroxide; the surfactant is at least one of polyvinylpyrrolidone and polyethylene glycol; the solution is at least one of ethylene glycol and glycerol; and the reducing agent is one of hydrazine hydrate, ascorbic acid, or sodium borohydride.

5. The preparation method according to claim 3, characterized in that, The weight ratio of tellurium source, alkali, reducing agent and surfactant is 1:1.2~3:8~15:0.7~1.

2.

6. The preparation method according to claim 3, characterized in that, The bismuth source is a bismuth salt; the zinc source is a zinc salt.

7. The application of zinc-doped bismuth telluride nanorods according to claim 1 or 2 in the preparation of reagents that promote the repair of infected wounds.

8. The application of zinc-doped bismuth telluride nanorods according to claim 1 or 2 in the preparation of antibacterial reagents.

9. A pharmaceutical hydrogel, characterized in that, By weight, the raw materials include 1-10 parts of zinc-doped bismuth telluride nanorods as described in claim 1 or 2, 5-50 parts of lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, 100-750 parts of gelatin methacrylate and 1000-7500 parts of sulfobetaine methacrylate.

10. The use of the pharmaceutical hydrogel according to claim 9 in the preparation of reagents or antibacterial reagents that promote the repair of infected wounds.

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