A photothermal response type Janus fiber dressing and a preparation method and application thereof

Abstract

The present application relates to the technical field of medical wound dressing, and provides a photothermal responsive Janus fiber dressing as well as a preparation method and application thereof.The Janus fiber dressing is prepared by compounding polycaprolactone / gelatin / curcumin nanofiber and polydopamine modified cotton gauze.The dressing has photothermal responsiveness and gradient structure, and can realize active exudate drainage / evaporation and synergistic sterilization under near-infrared light irradiation.Meanwhile, local photothermal can trigger on-demand release of curcumin in the PGC layer, play an anti-inflammatory effect, and at the same time, as a colorimetric pH sensor, realize real-time monitoring of the wound in situ.In an infected diabetic mouse model, the dressing exhibits a wound healing effect superior to that of a commercial cotton dressing by reducing inflammation, inhibiting bacterial colonization, promoting collagen deposition and angiogenesis.The Janus fiber dressing integrates exudate management-treatment-monitoring, and provides a new strategy for diabetic wound care.

Description

Technical Field

[0001] This invention relates to the field of medical wound dressing technology, and in particular to a photothermal responsive Janus fiber dressing, its preparation method, and its application. Background Technology

[0002] Diabetes is one of the most common chronic metabolic diseases worldwide. Some diabetic patients have a lifelong risk of chronic wounds such as diabetic foot ulcers, which have a high mortality rate. Deaths are mainly caused by intractable infections, progressive tissue necrosis, sepsis, and lower limb amputation.

[0003] Diabetic wound healing disorder is a complex pathological process that fundamentally disrupts the normal stages of inflammation, proliferation, and remodeling. This is mainly due to persistent high-glucose exudate, which promotes bacterial growth and the accumulation of reactive oxygen species (ROS), thereby exacerbating inflammation, hindering angiogenesis and cell migration, and ultimately delaying wound closure. Standard clinical treatments include debridement, topical antibiotics, negative pressure wound therapy, growth factor therapy, and wound dressings. Among these, wound dressings are the preferred option due to their ease of use, minimally invasive nature, and cost-effectiveness. Despite decades of clinical application, traditional dressings (such as gauze and bandages) only provide passive coverage and cannot actively regulate the complex pathological microenvironment of infected, highly exudative diabetic wounds. To overcome this limitation, Janus dressings with asymmetric wetting structures have emerged as a highly promising treatment strategy, enabling unidirectional drainage and maintaining a hygienic local microenvironment. Currently, various 2D / 3D materials, such as foam, sponge, hydrogel, and fiber, have been used to construct Janus dressings due to their high absorbency. Recent research has focused on optimizing fluid transport through gradient wettability multilayer structures, oriented pore structures, and conical micropore arrays to achieve efficient unidirectional exudate removal. However, this capillary-based unidirectional fluid transport is inherently limited by the absorption capacity of the hydrophilic layer, becoming ineffective once saturated. Furthermore, exudate retention within dressings provides a favorable environment for bacterial colonization and proliferation, persistently leading to infection and inflammation. Given these key limitations, there is an urgent need to develop advanced dressings that can sustainably and actively control exudate while simultaneously modulating the infection, inflammation, and oxidative microenvironment of diabetic wounds. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies and provides a photothermal-responsive Janus fiber dressing, its preparation method, and its applications. This invention provides a photothermal-responsive Janus fiber dressing that mimics transpiration, integrating photothermal-driven exudate management, antibacterial properties, and on-demand drug delivery functions, making it a synergistic therapeutic material for infectious diabetic wounds. The photothermal-responsive Janus fiber dressing consists of a PDA-modified hydrophilic fiber substrate, such as a cotton gauze outer layer (PC), and a three-phase nanofiber contact layer (PGC) composed of polycaprolactone (PCL), gelatin (Gel), and curcumin (Cur). This dressing combines photothermal responsiveness with a gradient structure. Under near-infrared (NIR) light, the asymmetric Janus structure enables unidirectional exudate drainage, while continuous evaporation flux under photothermal heating achieves sustained exudate removal and bacterial colonization inhibition, enabling active exudate drainage / evaporation and synergistic bactericidal action. Simultaneously, local photothermal induction of swelling-melting transformation in PGC fibers triggers the on-demand release of curcumin from the PGC layer, exerting anti-inflammatory effects. It also functions as a colorimetric pH sensor for real-time in-situ wound monitoring. In vivo studies in a diabetic mouse model have shown that this dressing effectively promotes immune regulation, reduces inflammation, inhibits bacterial colonization, promotes epidermal regeneration, collagen deposition, and angiogenesis, ultimately accelerating the entire chronic wound healing process. This multifunctional Janus dressing, integrating exudate management, treatment, and monitoring, holds promise as a novel strategy for diabetic wound care.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a photothermal responsive Janus fiber dressing, comprising the following steps:

[0007] A hydrophilic fiber substrate is immersed in a dopamine hydrochloride solution to obtain a dopamine hydrochloride modified hydrophilic fiber substrate.

[0008] Polycaprolactone and gelatin were added to a solvent, then curcumin was added and stirred to obtain a spinning solution.

[0009] Using a hydrophilic fiber substrate modified with dopamine hydrochloride as the receiving substrate, the spinning solution is deposited on the hydrophilic fiber substrate modified with dopamine hydrochloride by electrospinning and dried to obtain a photothermal responsive Janus fiber dressing.

[0010] Preferably, polycaprolactone and gelatin are added to the solvent to make the total concentration of polycaprolactone and gelatin 150~160mg / mL, and then curcumin is added to make the curcumin concentration 15~20mg / mL;

[0011] The mass ratio of polycaprolactone to gelatin is 9:1.

[0012] Preferably, the electrospinning parameters are: spinning voltage of 15~20 kV, flow rate of 1.0~1.5 mL / h, and receiving distance of 10~20 cm.

[0013] Preferably, the hydrophilic fiber substrate is immersed in a dopamine hydrochloride solution, washed, and dried to obtain a dopamine hydrochloride modified hydrophilic fiber substrate.

[0014] The soaking temperature is 20~25℃ and the soaking time is 3~48h.

[0015] Preferably, dopamine hydrochloride is dissolved in a 10-15 mM solution of tris(hydroxymethyl)aminomethane with a pH of 8-9 to obtain a dopamine hydrochloride solution; wherein the concentration of dopamine hydrochloride in the dopamine hydrochloride solution is 2-3 mg / mL.

[0016] Preferably, the solvent includes at least one of hexafluoroisopropanol, trifluoroethanol, dichloromethane, methanol, acetone, ethanol, and dimethylformamide.

[0017] Preferably, the hydrophilic fiber substrate is either hydrophilic cotton gauze or hydrophilic nonwoven fabric.

[0018] Secondly, the present invention also provides a photothermal responsive Janus fiber dressing, which is prepared using the aforementioned preparation method.

[0019] Thirdly, the present invention also provides an application of the photothermal responsive Janus fiber dressing prepared by the preparation method described above or the application of the photothermal responsive Janus fiber dressing described above, wherein the application includes at least one of the following:

[0020] Application in the preparation of drugs that promote wound healing in diabetic patients;

[0021] Application in the preparation of reagents for scavenging ROS and DPPH free radicals;

[0022] Applications in the preparation of antibacterial materials;

[0023] Applications in the preparation of anti-inflammatory drugs;

[0024] Application in the preparation of pH indicators;

[0025] Application in the preparation of drugs that promote collagen deposition and angiogenesis.

[0026] The photothermal responsive Janus fiber dressing, its preparation method, and its application of the present invention have the following advantages over the prior art:

[0027] This invention relates to a photothermal responsive Janus fiber dressing, which consists of a PDA-modified hydrophilic fiber substrate, such as a cotton gauze outer layer (PC), and a three-phase nanofiber contact layer (PGC) composed of polycaprolactone (PCL), gelatin, and curcumin. This dressing combines photothermal responsiveness with a gradient structure. Under near-infrared (NIR) light irradiation, the asymmetric Janus structure enables unidirectional drainage and evaporation of exudate. Under photothermal heating, the evaporation flux is continuously increased, achieving continuous exudate removal and bacterial colonization inhibition. It can achieve active exudate drainage / evaporation and synergistic bactericidal effects (approximately 86% bactericidal rate against E. coli and approximately 95% bactericidal rate against S. aureus). Simultaneously, local photothermal induction of swelling-melting transformation in the PGC fibers triggers the on-demand release of curcumin from the PGC layer, exerting anti-inflammatory effects. It also functions as a colorimetric pH sensor for real-time in-situ wound monitoring. In vivo studies in a diabetic mouse model have shown that this dressing effectively promotes immune modulation, reduces inflammation, inhibits bacterial colonization, epidermal regeneration, collagen deposition, and angiogenesis. It significantly accelerates wound closure in vivo (approximately 90% closure rate in the PCPGC group and approximately 62% in the CG group on day 15), and enhances angiogenesis, collagen deposition, and inflammation resolution, ultimately accelerating the entire chronic wound healing process. This multifunctional Janus dressing integrates exudate management, treatment, and monitoring, and holds promise as a novel strategy for diabetic wound care. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The preparation process, function, and repair mechanism of the photothermal responsive Janus fiber dressing of the present invention are described below.

[0030] Figure 2 Scanning electron microscope images, water contact angles, and infrared spectra of each component of the Janus fiber dressing prepared in Example 1 and Comparative Examples 1-3 are shown.

[0031] Figure 3 This refers to the unidirectional liquid transport performance of the Janus fiber dressing in Embodiment 1 of the present invention;

[0032] Figure 4 This is a schematic diagram illustrating the photothermal effect principle of the Janus fiber dressing of the present invention;

[0033] Figure 5 The curves showing the temperature change over time and the results of the cyclic stability test of the Janus fiber dressing under near-infrared light irradiation in Example 1 are shown.

[0034] Figure 6 These are the test results of the photothermal synergistic antibacterial properties of the Janus fiber dressing of the present invention;

[0035] Figure 7 The results of the photothermal-triggered curcumin release test of Janus fiber dressing in Example 1;

[0036] Figure 8 The results of in vitro bioactivity tests on the Janus fiber dressing prepared in Example 1;

[0037] Figure 9 The Janus fiber dressing prepared in Example 1 was immersed in PBS solution with pH 6.0~10.0, and the pH-induced color changes were recorded by mobile phone, and the RGB values ​​were extracted.

[0038] Figure 10 To establish fitting curves for R / G, R / B, and pH in RGB space;

[0039] Figure 11 The results show the wound healing in vivo in diabetic mice using the Janus fiber dressing prepared in Example 1. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0042] This application provides a method for preparing a photothermal responsive Janus fiber dressing, comprising the following steps:

[0043] S1. A hydrophilic fiber substrate is immersed in a dopamine hydrochloride solution to obtain a dopamine hydrochloride modified hydrophilic fiber substrate.

[0044] S2. Add polycaprolactone and gelatin to the solvent, then add curcumin and stir to obtain the spinning solution;

[0045] S3. Using a hydrophilic fiber substrate modified with dopamine hydrochloride as the receiving substrate, the spinning solution is deposited on the hydrophilic fiber substrate modified with dopamine hydrochloride by electrospinning and dried to obtain a photothermal responsive Janus fiber dressing.

[0046] In plants, transpiration can achieve continuous, unidirectional liquid transport driven by solar energy. Based on this, the present invention provides a method for preparing a photothermal responsive Janus fiber dressing. It utilizes the photothermal effect to simulate plant transpiration, converting near-infrared light into local heat to drive continuous evaporation, thereby providing an ideal exogenous energy source for the sustainable and active management of wound exudate. The photothermal responsive Janus fiber dressing of the present invention is composed of a PDA-modified hydrophilic fiber substrate, such as a cotton gauze outer layer (PC), and a three-phase nanofiber contact layer (PGC) of polycaprolactone (PCL), gelatin (Gel), and curcumin (Cur). This dressing combines photothermal responsiveness with a gradient structure. Under near-infrared (NIR) light, the asymmetric Janus structure enables unidirectional exudate drainage, while continuous evaporation flux under photothermal heating achieves sustained exudate removal and bacterial colonization inhibition, realizing active exudate drainage / evaporation and synergistic bactericidal action. Simultaneously, local photothermal induction of swelling-melting transformation in PGC fibers triggers the on-demand release of curcumin from the PGC layer, exerting anti-inflammatory effects. It also functions as a colorimetric pH sensor for in-situ real-time wound monitoring. In vivo studies in a diabetic mouse model have shown that this dressing effectively promotes immune regulation, reduces inflammation, inhibits bacterial colonization, epidermal regeneration, collagen deposition, and angiogenesis, ultimately accelerating the entire chronic wound healing process.

[0047] In some embodiments, polycaprolactone and gelatin are added to a solvent to make the total concentration of polycaprolactone and gelatin 150-160 mg / mL, and then curcumin is added to make the curcumin concentration 15-20 mg / mL.

[0048] The mass ratio of polycaprolactone to gelatin is 9:1.

[0049] In some embodiments, the electrospinning parameters are: spinning voltage of 15~20 kV, flow rate of 1.0~1.5 mL / h, and receiving distance of 10~20 cm.

[0050] In some embodiments, the hydrophilic fiber substrate is immersed in a dopamine hydrochloride solution, washed, and dried to obtain a dopamine hydrochloride modified hydrophilic fiber substrate.

[0051] The soaking temperature is 20~25℃ and the soaking time is 3~48h.

[0052] In some embodiments, dopamine hydrochloride is dissolved in a 10-15 mM solution of tris(hydroxymethyl)aminomethane with a pH of 8-9 to obtain a dopamine hydrochloride solution; wherein the concentration of dopamine hydrochloride in the dopamine hydrochloride solution is 2-3 mg / mL.

[0053] In some embodiments, tris(hydroxymethyl)aminomethane is dissolved in deionized water and stirred until completely dissolved. Then, 1 M HCl or 1 M NaOH is added dropwise while stirring with a pH meter to adjust the pH to 8-9, resulting in a tris(hydroxymethyl)aminomethane solution with a concentration of 10-15 mM and a pH of 8-9.

[0054] A hydrophilic fiber substrate is immersed in a dopamine hydrochloride solution, then removed and subjected to ultrasonic treatment, washing, and drying to obtain a dopamine hydrochloride modified hydrophilic fiber substrate.

[0055] In some embodiments, the solvent includes at least one of hexafluoroisopropanol, trifluoroethanol, dichloromethane, methanol, acetone, ethanol, and dimethylformamide.

[0056] In some embodiments, the hydrophilic fiber substrate is either hydrophilic cotton gauze or hydrophilic nonwoven fabric.

[0057] Based on the same inventive concept, the present invention also provides a photothermal responsive Janus fiber dressing, which is prepared using the above-described preparation method.

[0058] Based on the same inventive concept, the present invention also provides an application of the photothermal responsive Janus fiber dressing prepared by the above-mentioned preparation method, wherein the application includes at least one of the following;

[0059] Application in the preparation of drugs that promote wound healing in diabetic patients;

[0060] Application in the preparation of reagents for scavenging ROS and DPPH free radicals;

[0061] Applications in the preparation of antibacterial materials;

[0062] Applications in the preparation of anti-inflammatory drugs;

[0063] Application in the preparation of pH indicators;

[0064] Application in the preparation of drugs that promote collagen deposition and angiogenesis.

[0065] The following specific embodiments further illustrate the photothermal responsive Janus fiber dressing, its preparation method, and its application. This section further illustrates the content of the present invention with reference to specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0066] In the following examples, medical hydrophilic cotton gauze (CG) was purchased from Hubei Qianjiang Jianghe Medical Supplies Co., Ltd.; polycaprolactone (PCL, Mn=80000~100000), curcumin (Cur), hexafluoroisopropanol (HFIP), and rhodamine B (analytical grade) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; gelatin (Gel, type B), dopamine hydrochloride (DOPA, analytical grade), and tris(hydroxymethyl)aminomethane (THAM, analytical grade) were purchased from Sigma-Aldrich; Tween 80 (biotechnology grade) and phosphate buffered saline (PBS, pH=7.2~7.4) were purchased from Maclean Biochemical Technology Co., Ltd.

[0067] Example 1

[0068] This embodiment provides a method for preparing a photothermal responsive Janus fiber dressing, including the following steps:

[0069] S1, PDA-modified cotton gauze (PC) preparation: Dopamine hydrochloride was dissolved in 10 mM THAM solution with pH=8.5 to obtain dopamine hydrochloride solution; the concentration of dopamine hydrochloride in the dopamine hydrochloride solution was 2 mg / mL;

[0070] A 20 cm × 20 cm (i.e., both length and width are 20 cm) medical hydrophilic cotton gauze was placed in a dopamine hydrochloride solution and soaked at room temperature (25℃) for 24 h. The cotton gauze was then removed, washed three times with deionized water to remove unreacted substances, and dried overnight in a 70 ℃ oven to obtain PDA modified cotton gauze (PC).

[0071] S2. Preparation of PCL / Gel / Cur (PGC) spinning solution: Polycaprolactone (PCL) and gelatin (Gel) were dissolved in hexafluoroisopropanol (HFIP) at a mass ratio of 90:10 (i.e., 9:1) to make the total concentration of PCL and Gel 150 mg / mL. Curcumin (Cur) was then added to make the concentration of Cur 15 mg / mL. The mixture was magnetically stirred for 12 h until completely dissolved to obtain the spinning solution.

[0072] S3. Using PDA-modified cotton gauze (PC) as the receiving substrate, the spinning solution was loaded into the syringe of an electrospinning device and deposited onto the PDA-modified cotton gauze (PC) by electrospinning. The solution was then vacuum dried at 35 °C for 48 h to completely remove the solvent and stabilize the fiber structure (dense and uniform PGC nanofibers were seamlessly composited onto the PC substrate without obvious delamination, and a PGC layer was formed), thus obtaining photothermal responsive Janus fiber dressing (PCPGC).

[0073] The electrospinning parameters were as follows: spinning voltage of 18 kV, flow rate of 1.2 mL / h, and receiving distance of 15 cm.

[0074] Comparative Example 1

[0075] This comparative example provides a method for preparing Janus fiber dressing, which is the same as in Example 1, except that the mass ratio of polycaprolactone (PCL) to gelatin (Gel) is 80:20, and the other process parameters are the same as in Example 1.

[0076] Comparative Example 2

[0077] This comparative example provides a method for preparing Janus fiber dressing, which is the same as in Example 1, except that the mass ratio of polycaprolactone (PCL) to gelatin (Gel) is 70:30, and the other process parameters are the same as in Example 1.

[0078] Comparative Example 3

[0079] This comparative example provides a method for preparing Janus fiber dressing, which is the same as in Example 1, except that it contains only polycaprolactone (PCL) and no gelatin. That is, the mass ratio of PCL to gelatin is 100:0. All other process parameters are the same as in Example 1.

[0080] Comparative Example 4

[0081] This comparative example provides a method for preparing Janus fiber dressing, similar to Example 1, except that the cotton gauze is not subjected to PDA modification treatment. The method specifically includes the following steps:

[0082] Preparation of S1, PCL / Gel / Cur (PGC) spinning solution: Polycaprolactone (PCL) and gelatin (Gel) were dissolved in hexafluoroisopropanol (HFIP) at a mass ratio of 90:10 (i.e., 9:1) to make the total concentration of PCL and Gel 150 mg / mL. Curcumin (Cur) was then added to make the concentration of Curcumin 15 mg / mL. The mixture was magnetically stirred for 12 h until completely dissolved to obtain the spinning solution.

[0083] S3. Using cotton gauze as the receiving substrate, the spinning solution is loaded into the syringe of the electrospinning equipment and deposited onto the cotton gauze by electrospinning. The solution is then vacuum dried at 35 °C for 48 h to completely remove the solvent and stabilize the fiber structure, thus obtaining Janus fiber dressing (denoted as CPGC).

[0084] The electrospinning parameters were as follows: spinning voltage of 18 kV, flow rate of 1.2 mL / h, and receiving distance of 15 cm.

[0085] Performance Characterization

[0086] Figure 1The preparation process, function, and repair mechanism of the photothermal responsive Janus fiber dressing of the present invention are described below.

[0087] Figure 1 Figure (a) shows the preparation process of the PCPGC Janus dressing: initial medical cotton yarn is modified with polydopamine (PDA) to introduce catechol / amino functional groups, forming a PC matrix with both hydrophilicity and photothermal responsiveness; PDA endows the material with near-infrared photothermal conversion capability, which is the core basis for subsequent photothermal driven function. Polycaprolactone (PCL) serves as a hydrophobic framework, thermosensitive gelatin regulates thermal behavior to achieve drug release triggering, and curcumin (Cur) is incorporated as a therapeutic load, serving as an active functional substance. The three are combined to prepare a PGC spinning solution; curcumin simultaneously plays a triple role of anti-inflammatory, antioxidant, and pH sensing. Using PDA-modified cotton yarn as the receiving substrate, the PGC solution is deposited on the substrate surface through electrospinning to form an asymmetric PCPGC Janus dressing. Finally, the dressing is applied to the infected wounds of diabetic mice, and treatment is triggered by near-infrared light irradiation.

[0088] Figure 1 (b) represents the four core functional mechanisms of the dressing of this invention.

[0089] Photothermal Driven Fluid Conducting & Antibacterial

[0090] Under near-infrared irradiation, the PDA layer generates a photothermal effect, which on the one hand drives the wound exudate to achieve unidirectional transmission and rapid evaporation through the Janus structure, solving the problem of high exudate in diabetic wounds; on the other hand, the local heating directly destroys the bacterial cell membrane structure, achieving efficient sterilization.

[0091] Photothermal-driven drug release

[0092] When the temperature exceeds the melting (Tm) / swelling temperature of PCL / gelatin fibers, the hydrogen bonds of gelatin are broken, and the fiber structure swells / melts, achieving photothermal-triggered pulsed on-demand release; when there is no light, the drug release is slow, avoiding the side effects of burst release.

[0093] Free radical scavenging (antioxidant and anti-inflammatory)

[0094] The released curcumin can directly scavenge ROS (reactive oxygen species, including •OH, •O2, H2O2, etc.) in the wound microenvironment, while regulating macrophage polarization from the pro-inflammatory M1 type to the anti-inflammatory M2 type, inhibiting oxidative stress and chronic inflammatory response.

[0095] Real-time wound monitoring (pH sensing)

[0096] Curcumin, as a natural pH indicator, exhibits different colors in acidic (pH<7, healthy wound) and neutral / weakly alkaline (pH>7, infected wound) environments. It can achieve semi-quantitative real-time monitoring of wound pH through RGB signals to assess the infection status.

[0097] Figure 1 Image (c) illustrates the entire process of PCPGC Janus dressing-mediated diabetic wound repair:

[0098] Antibacterial stage

[0099] The photothermal effect directly kills bacteria on the wound, eliminating the source of infection and breaking the vicious cycle of "infection-inflammation".

[0100] Immune regulation phase

[0101] After curcumin is released, it clears ROS, thereby reducing the expression of pro-inflammatory factors such as IL-6 and TNF-α, and regulating the wound microenvironment from a chronic inflammatory state to a reparative state, creating conditions for tissue regeneration.

[0102] Tissue repair phase

[0103] Anti-inflammatory and antioxidant effects promote the expression of the vascular endothelial cell marker CD31, accelerating wound vascularization; at the same time, it recruits fibroblasts, upregulates the expression of proteins such as Vimentin, promotes collagen deposition and tissue remodeling, and ultimately achieves high-quality healing of diabetic infected wounds.

[0104] Figure 2 Scanning electron microscope images and water contact angles (measured using an optical contact angle meter (Theta-Flex, Sweden)) of the Janus fiber dressings prepared in Example 1 and Comparative Examples 1-3, and infrared spectra of the Janus fiber dressing prepared in Example 1 are shown below. Figure 2 (a) is a SEM image of the Janus fiber dressing prepared in Comparative Example 3; (b) is a SEM image of the Janus fiber dressing prepared in Example 1; (c) is a SEM image of the Janus fiber dressing prepared in Comparative Example 1; and (d) is a SEM image of the Janus fiber dressing prepared in Comparative Example 2.

[0105] Figure 2 In (e), CG represents the water contact angle of the medical hydrophilic cotton gauze (CG), PC represents the water contact angle of the PDA-modified cotton gauze (PC) in Example 1, and P 100 G0C represents the water contact angle of the Janus fiber dressing prepared in Comparative Example 3, P 90 G 10 C represents the water contact angle of the Janus fiber dressing prepared in Example 1, P 80 G20 C represents the water contact angle of the Janus fiber dressing prepared in Comparative Example 1, P 70 G 30 C represents the water contact angle of the Janus fiber dressing prepared in Comparative Example 2;

[0106] Figure 2 In the diagram (f), CG represents the infrared spectrum of medical hydrophilic cotton gauze (CG), PC represents the infrared spectrum of PDA modified cotton gauze (PC) in Example 1, Gel represents the infrared spectrum of gelatin, Cur represents the infrared spectrum of curcumin, PCL represents the infrared spectrum of polycaprolactone, and PGC represents the infrared spectrum of the three-phase nanofiber contact layer of polycaprolactone (PCL), gelatin (Gel), and curcumin (Cur) obtained by electrospinning.

[0107] from Figure 2 As can be seen from the scanning electron microscope images, the fiber diameter decreases slightly as the gelatin content increases.

[0108] from Figure 2 As can be seen from (e), CG and PC have water contact angles close to 0°, indicating superhydrophilicity; while P... 100 G0C, P 90 G 10 C, P 80 G 20 C, P 70 G 30 The water contact angles of C were 122.1°, 108.7°, 85.6°, and 49.2°, respectively; as the gelatin content increased from 0% to 30%, the water contact angle of the Janus fiber dressing gradually decreased from 122.1° to 49.2°, and the wettability changed from strongly hydrophobic to hydrophilic; P 100 G0C, lacking gelatin and thermoresponsiveness, cannot meet the needs of on-demand drug delivery; P 80 G 20 C, P 70 G 30 C, due to the fiber changing from hydrophobic to hydrophilic, lacks sufficient wettability with the hydrophilic substrate, resulting in insufficient single-phase liquid conductivity; while P... 90 G 10 C ensures the hydrophobicity of the fiber layer and forms a sufficient wettability difference with the hydrophilic substrate, providing a stable driving force for single-phase liquid transport. Therefore, a PCL to gel mass ratio of 90:10 is the optimal mass ratio.

[0109] from Figure 2 As can be seen in (f), both the CG and PC layers exhibit typical characteristics of cellulose: 3330 cm -1 -OH stretching vibration, 2902 cm -1CH stretching, 1018 cm -1 CO stretching. Compared to CG, PC at 1493 cm -1 The appearance of a new peak, attributed to the C=C stretching of the aromatic ring in PDA, directly proves the successful modification of PDA; the PGC layer exhibits three sets of superimposed characteristic peaks: 1160 and 1240 cm⁻¹ of PCL. -1 (Chocolate's symmetric and asymmetric stretching), 1723 cm -1 (C=O stretching); 1650 cm of gel -1 (Amide I with C=O stretching); Cur 1507 cm -1 (C=O stretching) and 1619 cm -1 (Aromatic ring C=C stretching) The above results confirm the successful preparation of PCPGC dressing.

[0110] Figure 3 To demonstrate the unidirectional liquid transport performance of the Janus fiber dressing in Example 1 of this invention, specifically, stained PBS droplets (3 mL / min) were introduced from the top and bottom of the fiber dressing to verify the asymmetric wettability-driven unidirectional liquid transport characteristic of the Janus dressing. The dressing structure consists of a hydrophilic PC layer (PDA-modified cotton yarn) on one side and a hydrophobic PGC layer (electrospun nanofibers) on the other side, forming a significant wettability gradient. Stained PBS droplets were added from above and below, respectively, and the liquid penetration behavior in different directions was observed to verify the unidirectional property that "transmission can only occur from the PGC layer to the PC layer, and is blocked in the reverse direction."

[0111] Specifically, Figure 3 (a) A droplet is applied from above to the hydrophilic PC layer. Upon landing on the hydrophilic layer, the droplet is blocked by the underlying hydrophobic layer and cannot penetrate the dressing. Actual photographs show that at 1 second, the droplet contacts the PC layer and quickly wets and spreads; from 5 to 30 seconds, the liquid remains on the PC layer surface, intercepted by the underlying hydrophobic PGC layer and unable to penetrate downwards. When liquid is applied from the PC layer, it cannot penetrate the dressing, and reverse transport is blocked.

[0112] Figure 3(b) A droplet is added from above to the PGC hydrophobic layer. Upon landing on the hydrophobic layer, the droplet is "pumped" by the underlying hydrophilic layer, penetrating the dressing and being completely absorbed by the PC layer. Actual photographs show: 1s: The droplet contacts the PGC layer but does not immediately spread, maintaining its droplet shape; 5-15s: The droplet is pulled by the capillary force of the underlying PC layer, gradually penetrating the PGC layer and being transported to the PC layer; 30s: The droplet is completely absorbed by the PC layer, and traces of liquid penetration are visible beneath the dressing. When liquid is added from the PGC layer, it can be rapidly pumped to the PC layer, achieving forward transport.

[0113] Figure 3 In diagram (c), a droplet is added from below to the PGC hydrophobic layer (anti-gravity transport). Upon contact with the PGC layer from below, the droplet is "pumped" upwards by the PC layer above, overcoming gravity and drying. The photograph shows that from 1-5 seconds, the droplet contacts the PGC layer from below and is pulled upwards by capillary force; from 15-30 seconds, the liquid completely penetrates the PGC layer, is absorbed by the PC layer above, and gradually dries. Even under anti-gravity conditions, the liquid can still be transported unidirectionally from the PGC layer to the PC layer, demonstrating that this process is dominated by the wettability gradient.

[0114] Figure 3 In (d), a droplet is added from below to the hydrophilic PC layer. When the droplet contacts the PC layer from below, it is blocked by the hydrophobic PGC layer above and cannot penetrate the dressing upwards. The actual photograph shows that from 1 to 30 seconds, the droplet remains below the PC layer and is blocked by the hydrophobic PGC layer above, unable to penetrate upwards. When liquid is added from the PC layer, the liquid cannot penetrate the dressing in the reverse direction, consistent with the result of (a), further verifying the unidirectionality.

[0115] Furthermore, Figure 4 The schematic diagram of the photothermal effect principle of the Janus fiber dressing of the present invention is shown. Polydopamine (PDA) in the dressing is the key component of the photothermal response. Under near-infrared light irradiation, PDA absorbs light energy, and electrons are excited from the ground state to the excited state. The excited state electrons are unstable. In the process of returning to the ground state, they release energy in the form of heat through non-radiative relaxation, realizing the conversion of light energy into heat energy and causing the dressing to heat up locally. This photothermal effect is the basis for subsequent photothermal sterilization, photothermal-driven drug release, and photothermal-assisted exudate evaporation.

[0116] Figure 5 The figures for Example 1 show the temperature change over time and cyclic stability test results of the Janus fiber dressing under near-infrared light irradiation; wherein, Figure 5In the middle (a), CG (medical cotton gauze), PGC (using aluminum foil or release paper as the receiving substrate, depositing a PGC layer on the receiving substrate according to the method in Example 1, and then peeling the PGC layer off the receiving substrate), PC (PDA modified cotton gauze), and PCPGC (Janus fiber dressing in Example 1) were respectively taken and tested using an 808 nm near-infrared laser (power density 1.0 W / cm²). 2 Different samples were irradiated, and temperature changes were recorded using an infrared thermal imager. CG, PGC, PC, and PCPGC samples were continuously irradiated for 120 seconds, and the temperature at different time points was recorded. The temperature difference from the initial temperature was calculated, and a curve of temperature change over time was obtained (the vertical axis represents the temperature difference from the initial temperature). Figure 5 In the (b) cycle stability test, the PCPGC sample underwent 5 “60 s irradiation-natural cooling” cycles, and the temperature change in each cycle was recorded to evaluate the repeatability and stability of the photothermal performance.

[0117] from Figure 5 As shown in (a): CG (medical gauze): minimal temperature rise, with a final temperature difference of only about 4-5℃, exhibiting almost no photothermal effect. PGC (pure nanofiber layer): limited temperature rise, with a final temperature difference of about 7-8℃, lacking PDA photothermal components, relying solely on weak material heat absorption, unable to achieve effective temperature rise. PC: rapid temperature rise, with a final temperature difference of about 23℃, demonstrating the excellent photothermal conversion capability of PDA. PCPGC: the temperature rise curve almost overlaps with PC, with a final temperature difference of about 24℃, proving that the PDA-modified layer maintains efficient photothermal performance after composite, and the nanofiber layer does not negatively affect photothermal conversion. The photothermal performance of PCPGC dressing is mainly contributed by the PDA-modified layer, with a temperature rise efficiency comparable to the pure PC layer, far exceeding the control group without PDA, providing a sufficient temperature rise basis for subsequent therapeutic functions.

[0118] from Figure 5 As can be seen in Figure (b), the heating rate, maximum temperature, and cooling rate did not decrease significantly during the 5 cycles, and the curve repeatability was excellent. The photothermal response of the PCPGC dressing showed excellent cyclic stability, indicating that the material would not degrade or degrade under repeated photothermal stimulation, and could support multiple on-demand treatments, demonstrating good potential for clinical application.

[0119] Figure 6 The results of the photothermal synergistic antibacterial properties of the Janus fiber dressing of the present invention;

[0120] Specifically, *Escherichia coli* (ATCC 25922) and *Staphylococcus aureus* (ATCC 25923) were inoculated into LB broth and cultured at 37°C and 180 rpm for 16 h until the logarithmic growth phase. The bacterial suspension was then diluted with sterile physiological saline to approximately 1 × 10⁻⁶. 6 CFU / mL, for later use; take CPGC (i.e., Janus dressing without PDA modification in Comparative Example 4) and PCPGC (Janus fiber dressing prepared in Example 1) and cut them into 10 mm diameter discs, sterilize them, and for later use; add 100 μL of the above bacterial suspension to the surface of each sample to ensure the bacterial solution evenly covers the dressing surface. For the "Near Infrared (+)" group, an 808 nm near-infrared laser (power density 1.0 W / cm²) was used. 2 Irradiate the sample surface for 1, 5, and 10 min respectively; the "near-infrared (-)" group is not irradiated and is placed at room temperature for the same time. After irradiation, the sample is transferred to a centrifuge tube containing 900 μL of sterile physiological saline and vortexed for 3 min to elute the viable bacteria on the dressing surface; take 100 μL of the eluent, serially dilute it and spread it on LB solid medium plates, incubate at 37℃, count the colonies on the plates and calculate the antibacterial rate.

[0121] Figure 6 (a) shows the results of plate colony counting: Group 0 represents CPGC dressing without near-infrared irradiation (CPGC (-)); Group 1 represents CPGC dressing with near-infrared irradiation for 10 min (CPGC (+)); Group 2 represents PCPGC dressing without near-infrared irradiation (PCPGC (-), 0 min); and Groups 3-5 represent PCPGC dressing with near-infrared irradiation for 1 / 5 / 10 min (PCPGC (+)).

[0122] For Escherichia coli (E. coli): Groups 0 / 1 / 2: ​​Regardless of near-infrared irradiation, the number of colonies in CPGC dressings (without PDA) and PGC dressings without light irradiation did not decrease significantly, indicating that the antibacterial effect of the dressings themselves is very weak without the photothermal effect of PDA. Groups 3-5: With prolonged near-infrared irradiation time, the number of colonies decreased significantly, and the colonies were almost completely inhibited at 10 min, proving that the bactericidal effect against E. coli under photothermal synergy increases over time.

[0123] For Staphylococcus aureus: Groups 0 / 1 / 2: ​​The number of colonies in the no-light or CPGC groups showed no significant change, indicating poor antibacterial effect. Groups 3-5: After 5 minutes of near-infrared irradiation, the number of colonies was significantly reduced; after 10 minutes, almost no colony growth was observed, indicating that the PCPGC dressing has a higher bactericidal efficiency against Staphylococcus aureus and can achieve near-complete eradication in a short time.

[0124] from Figure 6 As shown in Figure (b), groups 1-3 (no PDA or no light exposure): the antibacterial rate of E. coli was only 10%-35%, with a weak effect. Group 4 (PCPGC + near-infrared for 5 min): the antibacterial rate of E. coli increased to about 67%. Group 5 (PCPGC + near-infrared for 10 min): the antibacterial rate of E. coli was as high as about 86%, with a significant bactericidal effect.

[0125] from Figure 6 As shown in (c), in groups 1-3, the antibacterial rate against Staphylococcus aureus was only 5%-40%, with no significant effect. In group 4 (PCPGC + near-infrared for 5 min), the antibacterial rate against Staphylococcus aureus reached approximately 92%. In group 5 (PCPGC + near-infrared for 10 min), the antibacterial rate against Staphylococcus aureus was close to 95%, almost completely eradicating it. The photothermal synergistic antibacterial effect of PCPGC dressings showed a significant time dependence, and its killing efficiency against Staphylococcus aureus was superior to that against Escherichia coli.

[0126] As shown in Figure 6(d), on the left: the control group bacteria without near-infrared irradiation, cultured simply with PCPGC: *E. coli* exhibits a complete rod-shaped structure with a full morphology; *Staphylococcus aureus* is a regular spherical shape with a smooth surface. On the right: bacteria after 10 min of PCPGC + near-infrared irradiation: *E. coli* cells show obvious shrinkage and rupture, and their structural integrity is disrupted. *Staphylococcus aureus* shows surface depression and lysis, with cell contents leaking out and losing its normal morphology. This directly demonstrates that the photothermal effect can directly destroy the bacterial cell membrane structure, leading to bacterial death, and is direct evidence of antibacterial effect.

[0127] To verify whether PCPGC dressings can achieve on-demand and controllable release of curcumin through near-infrared photothermal effects, providing an "on-demand drug delivery" treatment option for diabetic wounds.

[0128] Figure 7 The results of photothermal-triggered curcumin release from Janus fiber dressing in Example 1.

[0129] Specifically, Janus fiber dressings were immersed in PBS buffer with a volume concentration of 1% Tween 80, and the fibers were intermittently irradiated with an 808 nm near-infrared laser six times (each irradiation lasting 10 min, with a 10 min interval between irradiations). Temperature changes were recorded using an infrared thermal imager, and the amount and rate of curcumin release were calculated. In the figure, NIR (+) indicates irradiation with near-infrared light, using an on / off pulse mode; NIR (-) indicates no near-infrared irradiation as a control.

[0130] from Figure 7 As can be seen in (a), without near-infrared irradiation (26.0 ℃): the dressing is kept at room temperature, the fibers are a dense, smooth, and complete mesh structure, the drug is wrapped in the fibers, and the release channels are not opened; when near-infrared irradiation is used (47.5 ℃): the dressing heats up rapidly, the fibers swell and melt and a large number of pores appear, forming drug release channels, which provides a structural basis for the rapid diffusion of curcumin.

[0131] from Figure 7 As shown in Figure (b), the group without near-infrared irradiation (NIR(-)) relies solely on passive diffusion for slow drug release, exhibiting a continuously rising curve with a consistently small slope and no significant fluctuations. The cumulative release percentage within 120 minutes is only about 30%, indicating high resistance to drug diffusion and a low, stable release percentage under light-free conditions. The group with near-infrared irradiation (NIR(+)) displays a significant "on-off" pulse release pattern: each time near-infrared is turned on, the curve slope increases significantly, and the release percentage surges; when near-infrared is turned off, the curve slope rapidly declines, and the release percentage immediately weakens. This periodic rate change is perfectly synchronized with the light switch, achieving a cumulative release percentage of approximately 86.7% within 120 minutes, significantly higher than the control group. This demonstrates that the near-infrared photothermal effect can efficiently trigger drug release and achieve precise control of the release rate.

[0132] from Figure 7 As shown in (c), in the near-infrared irradiation group (NIR (+)), the drug release per cycle was significantly higher than in the non-irradiation group. Although it decreased slightly with increasing cycle count, it still maintained stable photothermal responsiveness. In the non-near-infrared irradiation group (NIR (-)), the release remained at an extremely low level throughout each cycle, with no significant change. This demonstrates that the dressing can support multiple on-demand drug administrations with good cyclic stability.

[0133] Furthermore, the cumulative percentage of curcumin release and water contact angle of Janus fiber dressings prepared with different PCL to Gel mass ratios in Comparative Examples 1-3 were tested over 120 min using the method described above.

[0134] Table 1 shows the cumulative percentage of curcumin release and water contact angle of the Janus fiber dressings prepared in Example 1 and Comparative Examples 1-3.

[0135]

[0136] To achieve the unidirectional liquid delivery function of Janus dressing, the PGC contact layer needs to maintain sufficient hydrophobicity to form a significant wettability gradient with the PC hydrophilic layer. In Comparative Example 3 (PCL to Gel mass ratio of 100:0): the water contact angle is 122.1°, indicating excessive hydrophobicity and a lack of thermoresponsiveness in the fibers, resulting in a drug release percentage of only 25.6%, which cannot meet the on-demand drug delivery requirements. In Comparative Examples 1 (PCL to Gel mass ratio of 80:20) and 2 (PCL to Gel mass ratio of 70:30): as the Gel ratio increases, although the release percentage increases (88.1% and 91.6%, respectively), the hydrophilicity of the material significantly increases (contact angle decreases to 85.6° and 49.2°), losing the wettability gradient with the PC layer and compromising unidirectional delivery performance. In Example 1 (PCL to Gel mass ratio of 90:10): the water contact angle is 108.7°, maintaining both the hydrophobicity of the PGC layer and the wettability gradient with the PC layer. The hydrophilic layer forms a sufficient wettability gradient, resulting in optimal unidirectional liquid transport performance and a curcumin release percentage of 86.7%. In other words, the Janus fiber dressing prepared in Example 1 has the best unidirectional liquid transport performance while maintaining a relatively high curcumin release percentage, thus exhibiting the best overall performance.

[0137] Figure 8 The results are from the in vitro bioactivity test of the Janus fiber dressing prepared in Example 1.

[0138] Specifically, the in vitro biocompatibility of PCPGC (the Anus fiber dressing in Example 1) was assessed using mouse fibroblast L929 cells. The control group (a blank control group containing only cells and culture medium, without co-culturing with any dressing material), CG (medical gauze), PC (PDA-modified gauze), and PCPGC were sterilized under UV light for 60 min and immersed in DMEM culture medium for 24 h until saturation. L929 cells were cultured at a rate of 2 × 10⁻⁶ cells / year. 4 Cells / mL were seeded in 24-well plates and cultured in DMEM containing 10% fetal bovine serum and 1% penicillin-dextrose antibody at 37 °C and 5% CO2. Cell viability was assessed after 1, 2, and 3 days using a CCK-8 assay kit (Dojindo, Japan) and OD values ​​were measured at 450 nm using a Multiskan FC microplate reader (Thermo, USA). Simultaneously, cells were stained with calcein AM / PI double staining kit (Dojindo, Japan) and characterized under a fluorescence microscope.

[0139] Figure 8 (a) shows the cell viability / dead staining after co-culturing the control group, PCPGC dressing, and L929 cells; (b) and (c) show the absorbance (OD value) and cell viability percentage of the control group, CG, PC, and PCPGC at 450 nm, respectively, as detected by CCK-8 assay.

[0140] Live / dead staining showed that all groups (control, CG, PC, PCPGC) were predominantly live cells (green fluorescence) within 3 days, indicating no significant cytotoxicity. CCK-8 results further support this conclusion.

[0141] Figures 9-10 The results are the colorimetric pH response performance test results of the Janus fiber dressing prepared in Example 1.

[0142] Specifically, the Janus fiber dressing prepared in Example 1 was immersed in a PBS solution with a pH of 6.0–10.0, and the pH-induced color changes were recorded using a mobile phone. The RGB values ​​were extracted, and the results are as follows. Figure 9 As shown; a strict exponential relationship between R / G or R / B and pH is established in the RGB space, and a fitting curve is constructed. The results are as follows. Figure 10 As shown.

[0143] like Figure 10 As shown, the Janus fiber dressing of this invention exhibits a distinct pH-dependent color change: deep yellow in acidic / neutral environments and brownish-red under alkaline conditions. This colorimetric response was used to extract the corresponding RGB signals for quantitative analysis. The color change follows a regular, quantifiable pattern in the RGB space, with the R / G or R / B values ​​showing an approximately exponential relationship with the pH level: pH = 3.97ln((R / G - 0.41) / 0.11), pH = 2.02ln((R / B - 1.61) / 0.011), enabling semi-quantitative optical reading of the local wound microenvironment.

[0144] Figure 11 The results show the wound healing in vivo in diabetic mice using the Janus fiber dressing prepared in Example 1.

[0145] Specifically, to further evaluate the in vivo therapeutic effect of PCPGC (i.e., the Janus fiber dressing in Example 1), a diabetic model of S. aureus infection was established. Mice were housed in an SPF-grade environment (12-hour light / dark cycle, 22±2 ℃, 50±5% humidity) with free access to food and water. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ, Sigma-Aldrich) 50 mg / kg for 5 consecutive days; blood glucose was measured every 3 days using a blood glucose meter (Sinocare), and a blood glucose level >16.7 mmol / L maintained for 1 week was considered a successful model. Mice were anesthetized with isoflurane, their backs were shaved, and the wounds were disinfected with 75% ethanol. A 1 cm diameter full-thickness circular wound was prepared using a sterile biopsy drill; 50 μL of 1×10 8 A diabetic wound model was established using CFU / mL *S. aureus* bacterial suspension. Mice were randomly divided into three groups: (I) pure CG (medical gauze); (II) CG@PCL / Gel / Cur without PDA modification (CPGC, i.e., the Janus fiber dressing prepared in Comparison 4); and (III) PCPGC (i.e., the Janus fiber dressing in Example 1). For the first 3 days, the wound was irradiated with 808nm NIR (1 W / cm²) for 10 min daily. The dressing was changed every 3 days. Wound temperature was monitored using an infrared thermal imager, and body weight was recorded daily. Images were taken at 0, 3, 7, 11, and 15 days post-wound, and the wound area was measured using ImageJ.

[0146] from Figure 11The results show that the CG group had insufficient exudate management, with residual exudate still present on day 3; while CPGC and PCPGC achieved efficient exudate management, resulting in a cleaner wound bed. Correspondingly, the PCPGC group showed the most significant healing progress, with a wound closure rate of nearly 90% on day 15, significantly better than CG (approximately 62%) and CPGC (approximately 72%). This accelerated repair is partly due to photothermal enhancement of antibacterial activity. Under NIR irradiation, PCPGC rapidly increased the local temperature from 25.8 ℃ to 43.5 ℃ within 180 seconds, significantly higher than the CG control group (from 25.2 ℃ to 30.6 ℃). This targeted thermotherapy significantly reduced bacterial activity; exudate culture on day 3 showed a significant reduction in colony count in the PCPGC group. Collagen remodeling further confirmed the improved healing quality; Masson staining showed that, compared with the CG and CPGC control groups, the collagen deposition in the PCPGC-treated wound was denser and more regularly arranged. Notably, PCPGC regulates the time transition of collagen from type III to type I: type III collagen reaches an early peak on day 7, followed by a decline; type I collagen then shows a sustained increase. This trajectory replicates the typical process from temporary matrix formation to tissue maturation, highlighting PCPGC's ability to support wound regeneration with both structural and functional integrity.

[0147] In summary, this invention successfully developed a smart photothermal responsive Janus fiber dressing, PCPGC, for diabetic wound management. Under NIR irradiation, this dressing achieves continuous drainage and evaporation of exudate through a mimicking transpiration mechanism. This photothermal effect simultaneously endows PCPGC with potent antibacterial activity (approximately 86% against E. coli and approximately 95% against S. aureus) without causing thermal damage to normal tissue. Simultaneously, local photothermal triggering of the swelling-melting transition in the wound contact layer enables on-demand release of curcumin, serving as both an anti-inflammatory agent and a colorimetric pH indicator for real-time wound monitoring. This multifunctional synergistic effect achieves infection control, immune regulation, and tissue regeneration in a spatiotemporally coordinated manner, significantly accelerating wound closure in vivo (approximately 90% closure rate in the PCPGC group on day 15, compared to approximately 62% in the CG group), and enhancing angiogenesis, collagen deposition, and inflammation resolution.

[0148] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for preparing a photothermal responsive Janus fiber dressing, characterized in that, Includes the following steps: A hydrophilic fiber substrate was immersed in a dopamine hydrochloride solution to obtain a dopamine hydrochloride modified hydrophilic fiber substrate. Polycaprolactone and gelatin are added to a solvent to make the total concentration of polycaprolactone and gelatin 150~160mg / mL, then curcumin is added to make the curcumin concentration 15~20mg / mL, and the mixture is stirred to obtain a spinning solution. Using a hydrophilic fiber substrate modified with dopamine hydrochloride as the receiving substrate, the spinning solution was deposited on the hydrophilic fiber substrate modified with dopamine hydrochloride by electrospinning and dried to obtain a photothermal responsive Janus fiber dressing. The mass ratio of polycaprolactone to gelatin is 9:

1. The hydrophilic fiber substrate is either hydrophilic cotton yarn or hydrophilic nonwoven fabric.

2. The method for preparing the photothermal responsive Janus fiber dressing as described in claim 1, characterized in that, The electrospinning parameters are as follows: spinning voltage is 15~20 kV, flow rate is 1.0~1.5 mL / h, and receiving distance is 10~20 cm.

3. The method for preparing the photothermal responsive Janus fiber dressing as described in claim 1, characterized in that, The hydrophilic fiber substrate was immersed in a dopamine hydrochloride solution, washed, and dried to obtain a dopamine hydrochloride modified hydrophilic fiber substrate. The soaking temperature is 20~25℃ and the soaking time is 3~48h.

4. The method for preparing the photothermal responsive Janus fiber dressing as described in claim 1, characterized in that, Dopamine hydrochloride was dissolved in a 10-15 mM solution of tris(hydroxymethyl)aminomethane with a pH of 8-9 to obtain a dopamine hydrochloride solution; wherein the concentration of dopamine hydrochloride in the dopamine hydrochloride solution was 2-3 mg / mL.

5. The method for preparing the photothermal responsive Janus fiber dressing as described in claim 1, characterized in that, The solvent includes at least one of hexafluoroisopropanol, trifluoroethanol, dichloromethane, methanol, acetone, ethanol, and dimethylformamide.

6. A photothermal responsive Janus fiber dressing, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 5.

7. An application of a photothermal responsive Janus fiber dressing prepared by any one of claims 1 to 5, or the photothermal responsive Janus fiber dressing of claim 6, wherein, The application includes at least one of the following; Application in the preparation of drugs that promote wound healing in diabetic patients; Application in the preparation of reagents for scavenging ROS and DPPH free radicals; Applications in the preparation of antibacterial materials; Applications in the preparation of anti-inflammatory drugs; Application in the preparation of pH indicators; Application in the preparation of drugs that promote collagen deposition and angiogenesis.

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