An antibacterial biosafe coated cotton bandage and a method of making the same

Abstract

This invention belongs to the field of bandage technology and relates to an antibacterial biosafety coated cotton bandage and its preparation method. The antibacterial biosafety coated cotton bandage includes a cotton bandage substrate and sequentially formed fiber anchoring layer, recognition and capture layer, and in-situ bactericidal layer. The recognition and capture layer is modified with mannose or folic acid ligands to actively recognize pathogens, and the in-situ bactericidal layer is synergistically composed of nano-silver and quaternary ammonium salts to achieve spatially confined and highly efficient inactivation. By adopting the above technical solution, this application can improve the active capture rate and rapid bactericidal efficiency of free pathogens, and possesses excellent durability and biosafety.

Description

Technical Field

[0001] This invention belongs to the field of bandage technology and relates to an antibacterial biosafety coated cotton bandage and its preparation method. Background Technology

[0002] In high-risk infection areas, pathogens not only originate from direct contact, but also exist in large quantities through dynamic transmission pathways such as airborne particles, splashes of wound exudate, or the spread of bodily fluids. Under such complex conditions, traditional passive antimicrobial coatings are limited to killing pathogens upon contact and cannot actively intervene against free pathogens that have not yet come into contact with the bandage surface.

[0003] Furthermore, even if some microorganisms are killed, their remains may still remain on the bandage surface, forming biofilm precursors or triggering inflammatory responses; while live bacteria that are not removed in time may accumulate locally, migrate, or even penetrate the dressing barrier to invade the wound, leading to secondary infections. Existing coatings lack the ability to actively identify, target, and spatially confine pathogens. Summary of the Invention

[0004] To achieve the above-mentioned objectives, this invention provides an antibacterial biosafety coated cotton bandage and its preparation method. The antibacterial biosafety coated cotton bandage utilizes a composite coating system on the surface of cotton fibers that combines active recognition and capture with in-situ sterilization. This overcomes the limitations of traditional passive contact sterilization mechanisms, enabling active adsorption, spatial confinement, and efficient inactivation of free pathogens in dynamic environments, thereby enhancing its bioprotective efficacy in high-risk infection scenarios.

[0005] The antibacterial biosafety coated cotton bandage of this invention comprises a cotton bandage substrate and a composite functional coating formed on its surface. The composite functional coating, from the inside out, comprises: a fiber anchoring layer, a recognition and capture layer, and an in-situ bactericidal layer. The fiber anchoring layer is firmly bonded to hydroxyl groups on the surface of cotton fibers via covalent bonding; the recognition and capture layer is composed of grafted polymer chains with a spatially extended conformation, and its side chain ends are modified with mannose or folic acid ligands; the in-situ bactericidal layer is synergistically composed of nano-silver particles loaded in the network structure of the recognition and capture layer and quaternary ammonium salt functional units.

[0006] Furthermore, the fiber anchoring layer is constructed by the condensation reaction of 3-aminopropyltriethoxysilane with the hydroxyl groups on the surface of cotton fibers to form siloxane covalent bonds. The cotton bandage is immersed in a 2% (v / v) aqueous solution of 3-aminopropyltriethoxysilane in ethanol (ethanol to water volume ratio 95:5) and reacted at 60°C for 2 hours. It is then thoroughly washed with deionized water and vacuum dried at 60°C to obtain a modified cotton bandage with a surface rich in primary amines. These primary amines serve as initiation sites for subsequent polymerization reactions of the recognition and trapping layer, ensuring the chemical stability and durability of the coating structure.

[0007] Furthermore, the identification and trapping layer is formed by in-situ growth of poly(2-hydroxyethyl methacrylate-co-methacryloyloxyethyl mannoside) or poly(2-hydroxyethyl methacrylate-co-methacryloyloxyethyl folic acid) copolymer brushes on the fiber anchoring layer using surface-initiated atom transfer radical polymerization (SI-ATRP) technology. The monomer ratio is 9:1 to 7:3 molar ratio of 2-hydroxyethyl methacrylate (HEMA) to the functional monomer (methacryloyloxyethyl mannoside or methacryloyloxyethyl folic acid), preferably 8:2. The polymerization reaction system comprises: modified cotton bandage, CuBr / 2,2'-bipyridine catalytic system (molar ratio 1:1), monomer mixture, and N,N-dimethylformamide (DMF) solvent, and reacted at 70°C for 6 hours under nitrogen protection. The resulting polymer brushes have a number-average molecular weight of 80,000 to 120,000 and a grafting density of 0.35 to 0.55 chains / nm², ensuring that the ligands have sufficient conformational freedom and accessibility in three-dimensional space to achieve effective recognition and high-affinity binding to bacterial surface receptors.

[0008] The methacryloyloxyethyl mannoside was synthesized via the following steps: D-mannose (10.0 g, 55.5 mmol) was dissolved in anhydrous pyridine (50 mL), and 4-dimethylaminopyridine (DMAP, 0.68 g, 5.55 mmol) was added. Methacryl chloride (6.5 mL, 66.6 mmol) was slowly added dropwise under ice bath conditions. After the addition was complete, the mixture was brought to room temperature and reacted for 12 hours. The reaction solution was concentrated under reduced pressure, and the residue was dissolved in ethyl acetate. The residue was washed successively with 1 mol / L hydrochloric acid, saturated sodium bicarbonate solution, and saturated brine. After drying with anhydrous sodium sulfate, the residue was distilled under reduced pressure to obtain a white solid product.

[0009] The methacryloyloxyethyl folic acid was synthesized via the following steps: Folic acid (8.0 g, 18.2 mmol) and N-hydroxysuccinimide (NHS, 2.5 g, 21.8 mmol) were dissolved in anhydrous DMF (40 mL), and N,N'-dicyclohexylcarbodiimide (DCC, 4.5 g, 21.8 mmol) were added. The mixture was reacted at 0 °C for 2 hours, then at room temperature for another 12 hours. The dicyclohexylurea precipitate was removed by filtration. The filtrate was concentrated under reduced pressure, and 2-hydroxyethyl methacrylate (2.5 mL, 21.8 mmol) and 4-dimethylaminopyridine (0.22 g, 1.82 mmol) were added. The mixture was stirred at room temperature for 24 hours. The reaction solution was extracted with ethyl acetate, washed with water, dried, and purified by column chromatography (eluent: dichloromethane / methanol = 10:1) to obtain a pale yellow solid.

[0010] Furthermore, the in-situ bactericidal layer is constructed via a two-step method: first, quaternary ammonium salt functional units are introduced into the polymer network of the recognition and capture layer; second, nano-silver particles are generated in-situ within this network. Cotton bandages grafted with the recognition and capture layer are impregnated in an aqueous solution (0.1 mol / L) containing 2-(methacryloyloxy)ethyltrimethylammonium chloride (METAC), with ammonium persulfate (APS, 0.01 mol / L) added as an initiator. The reaction is carried out at 70°C for 2 hours, allowing METAC to be grafted onto the hydroxyl side groups of the polymer backbone via free radical addition, forming a quaternary ammonium salt functionalized network.

[0011] Subsequently, the bandage was transferred to a silver nitrate aqueous solution (concentration of 5 mmol / L) and soaked at 30°C in the dark for 30 minutes to allow the Ag to dissolve. + Ions are adsorbed around positively charged quaternary ammonium salt groups via electrostatic interactions; then immersed in a 0.1 mol / L sodium ascorbate aqueous solution and reacted at 40°C for 15 minutes to complete the Ag reaction. + The in-situ reduction generates silver nanoparticles with a particle size of 8 to 15 nm, which are uniformly dispersed in the three-dimensional network structure of the recognition and capture layer.

[0012] The particle size distribution of the silver nanoparticles was determined by transmission electron microscopy, with an average particle size of 12 nm and a standard deviation of less than 2 nm. X-ray photoelectron spectroscopy analysis showed that Ag3d... 5 / 2 The binding energy is 368.2 eV, confirming that it is zero-valent silver. The grafting amount of the quaternary ammonium salt group was calculated by elemental analysis of the nitrogen content, and was 0.85 mmol / g bandage.

[0013] In a preferred embodiment of the present invention, the recognition and capture layer employs mannose ligands, suitable for broad-spectrum recognition of Gram-positive bacteria (such as Staphylococcus aureus) and Gram-negative bacteria (such as Escherichia coli and Pseudomonas aeruginosa). Bacterial surfaces commonly express mannose-sensitive lectins (such as FimH protein), whose dissociation constant (Kd) with mannose ligands is within 10. -6 Up to 10 -7 The M-level ensures high affinity binding. As another preferred embodiment, the recognition and capture layer employs a folic acid ligand, suitable for the specific capture of pathogens expressing folic acid receptors (such as certain drug-resistant strains and fungi), with a binding affinity Kd of approximately 10. -8 M.

[0014] The preparation method of the antibacterial biosafety coated cotton bandage of the present invention includes the following steps:

[0015] Step 1: Pretreatment of cotton bandages. Pure cotton plain weave bandages (warp and weft density of 133×72 threads / inch, weight of 120g / m²) are ultrasonically cleaned with 1g / L sodium dodecyl sulfate solution at 50℃ for 30 minutes, rinsed with deionized water until neutral, and dried at 60℃ for later use.

[0016] Step 2: Constructing the fiber anchoring layer. The pretreated cotton bandage was immersed in a 2% 3-aminopropyltriethoxysilane ethanol aqueous solution (v / v, ethanol:water = 95:5) and reacted at 60°C for 2 hours. After removal, it was washed 3 times with anhydrous ethanol and vacuum dried at 60°C for 12 hours to obtain the aminated cotton bandage.

[0017] Step 3: Constructing the recognition and capture layer. The aminated cotton bandage was placed in a SI-ATRP reaction system containing: HEMA (8 mmol), methacryloyloxyethyl mannoside (2 mmol), CuBr (0.1 mmol), 2,2'-bipyridine (0.1 mmol), and DMF (20 mL). After three nitrogen purgings, the reaction was carried out at 70°C for 6 hours. After the reaction, the bandage was removed and ultrasonically washed three times each with DMF, ethanol, and deionized water, and then vacuum dried at 60°C to obtain the cotton bandage with the grafted copolymer brush.

[0018] Step 4: Constructing the in-situ bactericidal layer. First, immerse the bandage obtained in Step 3 in a 0.1 mol / L LMETAC aqueous solution, add 0.01 mol / L LAPS, and react at 70°C for 2 hours; then remove and wash with water. Subsequently, immerse it in a 5 mmol / L LAgNO3 aqueous solution and adsorb at 30°C in the dark for 30 minutes; then transfer it to a 0.1 mol / L sodium ascorbate aqueous solution and reduce at 40°C for 15 minutes. Finally, wash thoroughly with deionized water and dry at 60°C to obtain the antibacterial biosafety coated cotton bandage.

[0019] The antibacterial biosafety coated cotton bandage of this invention exhibits significantly superior protective performance compared to traditional antibacterial cotton bandages under dynamic pathogen exposure conditions. In a simulated wound exudate splash experiment, 10... 6 A CFU / mL E. coli suspension was sprayed onto the bandage surface at a speed of 0.5 m / s.

[0020] Furthermore, the coating of this invention maintains stable recognition ability in complex bodily fluid environments. After incubation in phosphate buffer containing 10% fetal bovine serum for 24 hours, its capture efficiency against Staphylococcus aureus remains above 92%, indicating that the polymer brush structure effectively resists interference from non-specific protein adsorption.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. By using a biomimetic recognition mechanism, it can actively capture free pathogens, breaking through the spatial and temporal limitations of traditional passive sterilization and improving dynamic protection capabilities;

[0023] 2. The capture and sterilization functions are highly synergistic in space. The captured pathogens are confined to a microenvironment with a high concentration of bactericide, achieving efficient in-situ inactivation and avoiding the migration of live bacteria and the formation of biofilms.

[0024] 3. Mannose / folic acid ligands endow the coating with broad-spectrum or targeted recognition capabilities, adapting to different pathogen exposure scenarios;

[0025] 4. The polymer brush structure constructed by SI-ATRP technology has both high ligand density and spatial accessibility, while providing a stable loading matrix for silver nanoparticles to ensure long-lasting functionality.

[0026] 5. The entire preparation process is based on an aqueous phase or low-toxicity solvent system, which meets the safety requirements of biomedical materials and is compatible with existing textile finishing processes, making it feasible for industrialization. Detailed Implementation

[0027] This invention provides an antibacterial biosafety coated cotton bandage and its preparation method. By constructing a composite coating system on the surface of cotton fibers that combines active recognition and capture with in-situ sterilization, it overcomes the limitations of traditional passive contact sterilization mechanisms, achieving active adsorption, spatial confinement, and efficient inactivation of free pathogens in dynamic environments, thereby enhancing its bioprotective efficacy in high-risk infection scenarios. The antibacterial biosafety coated cotton bandage includes a cotton bandage substrate and a composite functional coating formed on its surface. The composite functional coating, from the inside out, comprises a fiber anchoring layer, a recognition and capture layer, and an in-situ sterilization layer. The fiber anchoring layer is firmly bonded to hydroxyl groups on the surface of the cotton fibers via covalent bonding; the recognition and capture layer consists of grafted polymer chains with a spatially extended conformation, with mannose or folic acid ligands modified at the end of the side chains; the in-situ sterilization layer is composed of nano-silver particles loaded in the network structure of the recognition and capture layer and quaternary ammonium salt functional units.

[0028] The technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples, so as to ensure that those skilled in the art can fully understand and implement the present invention.

[0029] Based on the technical solution of this invention, the embodiments focus on the composite structure of fiber anchoring layer-recognition and capture layer-in-situ sterilization layer. By adjusting parameters such as recognition ligand type, monomer ratio, nano-silver particle size, and quaternary ammonium salt grafting amount, the embodiments cover broad-spectrum and targeted recognition scenarios, verifying performance under different process conditions. Specific parameters for the embodiments are as follows:

[0030]

[0031] The comparative examples address the shortcomings of traditional technologies, namely unmodified bandages, traditional silver-coated bandages, and incomplete structures lacking a bactericidal layer. Specific parameters for the comparative examples are as follows:

[0032]

[0033] Performance testing focused on indicators including pathogen capture rate, sterilization rate, durability (after 50 standard washes), and resistance to serum interference (in phosphate buffer containing 10% fetal bovine serum). The tested bacterial species were *Escherichia coli* (broad-spectrum bacteria) and *Staphylococcus aureus* (Gram-positive bacteria). Performance test data comparison table:

[0034]

[0035] All examples achieved E. coli capture rates exceeding 95% and sterilization rates exceeding 99.9%, significantly superior to Comparative Example 1 (capture rate 12.3%, sterilization rate 5.0%) and Comparative Example 2 (capture rate 35.6%, sterilization rate 68.2%). The reason is:

[0036] 1. The mannose / folic acid ligands in the capture layer can actively bind to bacterial surface receptors (such as mannose-sensitive lectins and folic acid receptors) to achieve active capture, breaking through the limitations of passive contact in traditional bandages.

[0037] 2. The synergistic effect of nano-silver and quaternary ammonium salt in the in-situ bactericidal layer confines the captured pathogens to a microenvironment with a high concentration of bactericidal agent, achieving efficient inactivation and preventing the migration of live bacteria.

[0038] Mannose ligands (Examples 1, 3, 5) showed better capture effects against broad-spectrum bacteria such as Escherichia coli and Staphylococcus aureus (capture rate 95.2%-98.7%); folic acid ligands (Examples 2, 4, 6) were more suitable for pathogens expressing folic acid receptors, and had advantages in specific scenarios (such as drug-resistant bacteria).

[0039] When the molar ratio of HEMA to functional monomer is 8:2 (Examples 1, 4, 5, 6), the capture rate and sterilization rate are better (capture rate 96.8%-98.7%, sterilization rate 99.97%-99.99%). This ratio balances the ligand density and the spatial accessibility of the polymer brush, ensuring sufficient recognition sites while avoiding ligand aggregation.

[0040] When the grafting amount was 0.85-0.95 mmol / g bandage (Examples 1, 2, 4, 6), the sterilization rate was close to 99.99%. When it was below 0.80 mmol / g (Examples 3, 5), the sterilization rate decreased slightly, indicating that the quaternary ammonium salt concentration directly affects the sterilization efficiency.

[0041] When the bandage concentration is 1.2-1.5 mmol / g (Examples 1, 2, 4, 5, 6), the coating bond is stronger, and the capture rate remains above 89.5% after 50 washes, ensuring durability.

[0042] After 50 standard washes, the capture rate of E. coli in the example remained above 88.0%, significantly better than that of Comparative Example 2 (20.3%). This is because the fiber anchoring layer is covalently bonded to the cotton fiber through siloxane bonds, and the recognition and capture layer grows in situ through surface-initiated atom transfer radical polymerization, resulting in a stable structure. In an environment containing 10% fetal bovine serum, the capture rate of Staphylococcus aureus in the example exceeded 91.0%, far superior to that of Comparative Example 2 (30.5%). This indicates that the polymer brush structure can resist non-specific protein adsorption and is suitable for complex body fluid scenarios (such as wound dressings).

[0043] Although Comparative Example 3 achieved a 98.5% capture rate of E. coli due to the recognition and capture layer, the sterilization rate was only 12.3% without the in-situ sterilization layer, making it impossible to achieve a capture-inactivation closed loop. In contrast, the collaborative design of the recognition and capture layer and the in-situ sterilization layer in the embodiment ensures rapid inactivation after capture, avoiding pathogen residue that could lead to inflammation or biofilm formation.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An antibacterial biosafety coated cotton bandage, comprising a cotton bandage substrate and a composite functional coating formed on its surface, characterized in that: The composite functional coating comprises, from the inside out, a fiber anchoring layer, an identification and capture layer, and an in-situ sterilization layer. The fiber anchoring layer is firmly bonded to the hydroxyl groups on the surface of the cotton fiber by siloxane covalent bonds. The fiber anchoring layer is formed by the condensation reaction of 3-aminopropyltriethoxysilane with the hydroxyl groups on the surface of the cotton fiber, and the surface amino density is 1.0–1.5 mmol / g bandage. The recognition and capture layer is composed of grafted polymer chains grown in situ through surface-initiated atom transfer radical polymerization, with the side chain ends modified with mannose ligands or folic acid ligands. The recognition and capture layer is one of poly(2-hydroxyethyl methacrylate-co-methacryloyloxyethyl mannoside) or poly(2-hydroxyethyl methacrylate-co-methacryloyloxyethyl folic acid) copolymer brush. The in-situ sterilization layer is composed of silver nanoparticles loaded in the three-dimensional network structure of the recognition and capture layer and quaternary ammonium salt functional units. The quaternary ammonium salt functional units are covalently grafted onto the hydroxyl side groups of the polymer chain through a free radical addition reaction. The silver nanoparticles are uniformly dispersed in the network structure.

2. The antibacterial biosafety coated cotton bandage according to claim 1, characterized in that: The number-average molecular weight of the copolymer brushes is 80,000 to 120,000, and the grafting density is 0.35 to 0.55 chains / nm².

3. The antibacterial biosafety coated cotton bandage according to claim 1, characterized in that: The quaternary ammonium salt functional unit is a 2-(methacryloyloxy)ethyltrimethylammonium chloride grafted structure with a grafting amount of 0.75–0.95 mmol / g bandage.

4. The antibacterial biosafety coated cotton bandage according to claim 1 or 3, characterized in that: The average particle size of the silver nanoparticles is 8 to 15 nm, and they exist in a zero-valence state.

5. The antibacterial biosafety coated cotton bandage according to claim 1, characterized in that: When the recognition and capture layer uses mannose ligands, its dissociation constant Kd for Escherichia coli, Staphylococcus aureus, or Pseudomonas aeruginosa is 10. -6 Up to 10 -7 M.

6. The antibacterial biosafety coated cotton bandage according to claim 1, characterized in that: When the recognition and capture layer uses a folic acid ligand, its dissociation constant Kd for pathogens expressing folic acid receptors is 10. -8 The order of magnitude is in the order of M.

7. A method for preparing an antibacterial biosafety coated cotton bandage as described in any one of claims 1-6, characterized in that... Includes the following steps: S1: Pre-treat the cotton bandage to obtain a clean substrate with exposed hydroxyl groups; S2: The substrate is immersed in an aqueous solution of 3-aminopropyltriethoxysilane ethanol and reacted at 60°C for 2 hours to construct a fiber anchoring layer; S3: Under nitrogen protection, using CuBr / 2,2'-bipyridine as a catalytic system, a surface-initiated atom transfer radical polymerization reaction was carried out at 70°C for 6 hours to grow a copolymer brush containing mannose or folic acid ligands in situ on the fiber anchoring layer, forming a recognition and capture layer; S4: First, the bandage is immersed in an aqueous solution containing 2-(methacryloyloxy)ethyltrimethylammonium chloride and ammonium persulfate and reacted at 70°C for 2 hours to achieve quaternary ammonium salt functionalization; then, it is successively adsorbed by silver nitrate solution and reduced by sodium ascorbate solution to generate nano-silver particles in situ and construct an in situ bactericidal layer.

8. The preparation method according to claim 7, characterized in that: In step S4, the concentration of silver nitrate solution is 5 mmol / L, the adsorption temperature is 30℃, and the time is 30 minutes; the concentration of sodium ascorbate solution is 0.1 mol / L, the reduction temperature is 40℃, and the time is 15 minutes.

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