Preparation method and application of high-efficiency antibacterial starch graft copolymer nanofiber drug-loaded membrane

Abstract

The application discloses a high-efficiency antibacterial starch graft copolymer nanofiber drug-loaded film and a preparation method and application thereof, and specifically relates to the following steps: taking high straight-chain corn starch as raw material, adopting an H2O2 oxidation-reduction system to graft hydroxybutyl acrylate and (3-acrylamide propyl) trimethylammonium chloride onto the high straight-chain corn starch to prepare an amphiphilic starch graft copolymer, and adopting electrospinning to prepare the starch graft copolymer nanofiber drug-loaded film. 2+ The starch graft copolymer nanofiber drug-loaded film prepared by the application has good compatibility between the starch graft copolymer and the drug, the cumulative release rate of the drug is obviously reduced, the drug release time is more durable, long-time drug release and sustained drug delivery can be realized, the drug-loaded film has excellent antibacterial property, high porosity and strong water vapor permeability, can provide better air permeability and oxygen permeability when used as an external dressing, and can be applied to slow-release drugs or medical materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biomedicine, and specifically discloses a preparation method and application of a starch graft copolymer nanofiber drug-loaded film with high antibacterial efficiency. BACKGROUND

[0002] In recent years, with the rapid economic development, the increasingly tight oil resources and the continuously rising oil prices, and a series of major environmental pollution problems caused by processing various polymer materials with petroleum chemical products as main raw materials, the application research of corn starch, which is a natural polymer material with low price, natural renewable, good environmental performance, degradable, and meeting the requirements of environmental protection and sustainable development strategy, has been increasingly valued by people and widely used in textile warp sizing, papermaking, food, plastic and medicine fields. However, there are a large number of glucose ring structures in starch macromolecules, which causes the starch film to have the characteristics of “hard and brittle”; the starch molecules contain a large number of hydroxyl groups, and there are hydroxyl groups on the 2, 3 and 6 carbons of each glucose unit, which form a large number of hydrogen bonds between and among the molecules. Although the hydrogen bond itself has weak force, due to the large number of hydrogen bonds, the intermolecular connection is very tight, and the molecular movement is difficult, resulting in poor processability of the starch. These all seriously affect the application effect of the starch in the above fields.

[0003] At present, some scholars have carried out related research on the preparation of starch nanofiber film by electrospinning. However, the pure starch fiber film prepared by electrospinning still has some defects, such as large water swelling, which causes the drug to be quickly dispersed into water due to the large water swelling of the starch nanofiber when the pure starch fiber film is used as a drug carrier, and the drug has very poor drug release performance, so that the long-acting drug release cannot be achieved. In addition, the pure starch fiber film does not have antibacterial property, and when the drug (such as aspirin) with anti-inflammatory and analgesic property is loaded, the drug-loaded film formed does not have antibacterial property. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a preparation method and application of a starch graft copolymer nanofiber drug-loaded film with high antibacterial efficiency, which connects the grafting branch capable of exhibiting “remote action” to the starch molecular chain to prepare a starch grafting polymer, and uses the antibacterial property of the grafting branch and the electrostatic force generated between the grafting branch and the drug to overcome the performance problems of the pure starch nanofiber drug-loaded film prepared by electrospinning, so as to obviously improve the drug release effect and antibacterial effect of the drug-loaded film.

[0005] To solve the above technical problem, the present application provides a preparation method of a starch graft copolymer nanofiber drug-loaded film with high antibacterial efficiency, which comprises the following steps:

[0006] (1) preparing a starch graft copolymer: Fe2+ -H2O2 redox system, hydroxybutyl acrylate and (3-acrylamido propyl) trimethyl ammonium chloride are grafted onto high straight chain corn starch to prepare starch graft copolymer;

[0007] (2) electrospinning starch graft copolymer nanofiber drug-loaded film: the starch graft copolymer prepared in step (1) is dissolved in a polar organic solvent to form a starch graft copolymer solution, a drug to be loaded is added to the starch graft copolymer solution, heated to 50-90℃ and stirred until the solution becomes transparent, a spinning solution is obtained, and the spinning solution is electrospun to obtain a starch graft copolymer nanofiber drug-loaded film.

[0008] As a further description of the above technical solution, step (1) is specifically: high straight chain corn starch is added to an alcohol-water mixture to prepare a starch milk, the pH of the starch milk is adjusted to 3-4, and under nitrogen protection, hydroxybutyl acrylate, (3-acrylamido propyl) trimethyl ammonium chloride, an aqueous ferrous ammonium sulfate solution and an aqueous hydrogen peroxide solution are simultaneously added to the starch milk within 30-40 min, and the reaction is continuously carried out under anaerobic conditions at 30-40℃ for 4-8 hours, the pH value is adjusted to 6-7, the filter cake is filtered, washed, crushed and dried to obtain the starch graft copolymer.

[0009] As a further description of the above technical solution, the volume ratio of alcohol to water in the alcohol-water mixture is (3-5):1, and the mass fraction of the starch milk is 20-40%.

[0010] As a further description of the above technical solution, the mass fraction of the aqueous ferrous ammonium sulfate solution is 0.5%, and the mass fraction of the aqueous hydrogen peroxide solution is 0.1%.

[0011] As a further description of the above technical solution, the organic solvent is dimethyl sulfoxide, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, pyridine or trichloromethane.

[0012] As a further description of the above technical solution, the drug to be loaded in step (2) is a drug that needs to be released, such as some drugs for treating chronic diseases, and the addition amount of the drug is 8-15% of the mass of the starch graft copolymer. Specifically, the drug to be loaded is aspirin, ibuprofen, acetaminophen, benorylate or indomethacin.

[0013] The application also provides the use of the high-efficiency antibacterial starch graft copolymer nanofiber drug-loaded film in a drug release system or a medical material, wherein the drug release system includes but is not limited to some anti-inflammatory, analgesic, antipyretic and chronic disease treatment release drugs, and the medical material includes but is not limited to some release drug dressings for treating trauma.

[0014] Compared with the prior art, the application has the following advantages:

[0015] (1) The starch graft copolymer and the drug in the nanofiber drug-loaded film prepared by the application have good compatibility;

[0016] (2) Compared with the drug-loaded film prepared directly by using starch, the drug cumulative release rate of the nanofiber drug-loaded film prepared by using the starch graft copolymer in the application is obviously reduced, the drug release time is more durable, long-term drug release and sustained drug delivery can be achieved, and the nanofiber drug-loaded film can be used for treating some chronic diseases that are difficult to eradicate at one time, such as cardiovascular diseases, cancers, diabetes, etc.;

[0017] (3) The starch graft copolymer nanofiber drug-loaded film also has high porosity and strong water vapor permeability, and can provide better air permeability and oxygen permeability for wound dressing, which is beneficial to wound healing;

[0018] (4) The introduction of two graft monomer units makes the starch have hydrophilic characteristics, thereby enhancing the combination between the starch and water molecules, increasing the swelling rate, and making the nanofiber drug-loaded film less affected in the human body or different environments, that is, the starch graft copolymer nanofiber drug-loaded film prepared by the application has strong environmental stability;

[0019] (5) The (3-acrylamidopropyl) trimethylammonium chloride monomer is grafted onto the starch to play a role in sterilization and antibiosis, and compared with the nanofiber drug-loaded film prepared by using starch, the nanofiber drug-loaded film prepared by using the starch graft copolymer in the application has excellent antibacterial performance, and the bacteriostatic rate basically reaches 100%. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a molecular structure diagram of the starch graft copolymer prepared by the application;

[0021] Figure 2 is an SEM diagram of sample 1, sample 2, sample 3 and sample 0;

[0022] Figure 3 is a standard curve diagram of aspirin;

[0023] Figure 4 is a drug cumulative release rate diagram of the nanofiber drug-loaded film of sample 1, sample 2, sample 3 and sample 0;

[0024] Figure 5 is a porosity column diagram of the nanofiber drug-loaded film of sample 1, sample 2, sample 3 and sample 0;

[0025] Figure 6 is a contact angle of the nanofiber drug-loaded film of sample 1, sample 2, sample 3 and sample 0;

[0026] Figure 7 is a column chart of the swelling rate results of the nanofiber drug-loaded films of sample 1, sample 2, sample 3 and sample 0;

[0027] Figure 8 is a column chart of the water vapor transmission rate results of the nanofiber drug-loaded films of sample 1, sample 2, sample 3 and sample 0.

[0028] Figure 9 is an antibacterial effect diagram of the nanofiber drug-loaded films of sample 0 and sample 3 on E. coil;

[0029] Figure 10 is an antibacterial effect diagram of the nanofiber drug-loaded films of sample 0 and sample 3 on S. aureus. DETAILED DESCRIPTION

[0030] The application will be further described below in conjunction with the specific embodiments.

[0031] Example 1

[0032] The present embodiment provides a preparation method of a high-efficiency antibacterial starch graft copolymer nanofiber drug-loaded film, comprising the following steps:

[0033] (1) Preparation of starch graft copolymer: by using Fe 2+ -H2O2 redox system, hydroxybutyl acrylate and (3-acrylamidopropyl) trimethylammonium chloride two monomers are grafted onto high-amylose corn starch to prepare a starch graft copolymer, specifically:

[0034] Take 120g of high-amylose corn starch with dry weight and add it to a 3:1 volume ratio of alcohol-water mixture to prepare a starch milk with a mass fraction of 20%. Adjust the pH to 3-4 with dilute hydrochloric acid and transfer it to a four-necked flask for thorough stirring. After heating in a water bath to 40℃, introduce nitrogen for 30min and under nitrogen protection, add 40g of hydroxybutyl acrylate, 20g of (3-acrylamidopropyl) trimethylammonium chloride, 0.5% of ferrous ammonium sulfate by mass fraction, and 1.0% of hydrogen peroxide aqueous solution by mass fraction according to the required amount into the starch milk at the same time, and require that the addition be completed within 30-40min, and then continuously anaerobic reaction for 4 hours. Adjust the pH of the graft product to 6-7 with 6% sodium carbonate solution, filter and wash several times, then crush the filter cake and dry it in an oven to obtain the starch graft copolymer. The molecular structure is shown in Figure 1 The grafting rate of the starch graft copolymer is 17.08%.

[0035] (2) Electrospinning of starch graft copolymer nanofiber drug-loaded film:

[0036] A certain amount of starch graft copolymer prepared in step (1) is weighed, the starch graft copolymer is dissolved in dimethyl sulfoxide, the mass fraction of the starch graft copolymer is 15%, 8% of aspirin, a drug requiring sustained release, by mass of the starch graft copolymer is added, heating is performed to 50°C and stirring is performed using a magnetic stirrer until the solution becomes transparent, standing is performed until defoaming, and a spinning solution is obtained; the spinning environment temperature of the electrospinning equipment is adjusted to 60°C, the voltage is 20 kV, the distance between the syringe and the drum is 15 cm, and the advancing speed is 1 mL / h, and electrospinning is performed on the spinning solution to obtain a starch graft copolymer nanofiber drug-loaded membrane, which is recorded as sample 1.

[0037] Example 2

[0038] The present embodiment provides a preparation method of a high-efficiency antibacterial starch graft copolymer nanofiber drug-loaded membrane, which comprises the following steps:

[0039] (1) Preparation of starch graft copolymer:

[0040] 120 g of dry high-amylose corn starch is weighed and added to an alcohol-water mixture with a volume ratio of 5:1 to prepare a starch milk with a mass fraction of 40%, dilute hydrochloric acid is used to adjust the pH to 3-4, and the mixture is transferred to a four-necked flask for thorough stirring. After water bath heating to 40°C, nitrogen is introduced for 30 min, and 40 g of hydroxybutyl acrylate, 30 g of (3-acrylamidopropyl) trimethylammonium chloride, 0.5% of ferrous ammonium sulfate by mass fraction, and 1.0% of hydrogen peroxide aqueous solution by mass fraction are simultaneously added dropwise to the starch milk under nitrogen protection, and the dropping should be completed within 30-40 min, and then continuous anaerobic reaction is performed for 5 hours. A 6% sodium carbonate solution is used to adjust the pH of the grafted product to 6-7, the filter cake is crushed and dried in an oven after several times of suction filtration and washing, and is packed for standby use, a starch graft copolymer is obtained, the molecular structure is as shown in Figure 1 The grafting rate of the starch graft copolymer is 23.17%.

[0041] (2) Electrospinning of starch graft copolymer nanofiber drug-loaded membrane:

[0042] A certain amount of starch graft copolymer prepared in step (1) is weighed, the starch graft copolymer is dissolved in dimethyl sulfoxide, the mass fraction of the starch graft copolymer is 40%, 15% of aspirin by mass of the starch graft copolymer is added, heating is performed to 90°C and stirring is performed using a magnetic stirrer until the solution becomes transparent, standing is performed until defoaming, and a spinning solution is obtained; the spinning environment temperature of the electrospinning equipment is adjusted to 60°C, the voltage is 20 kV, the distance between the syringe and the drum is 15 cm, and the advancing speed is 1 mL / h, and electrospinning is performed on the spinning solution to obtain a starch graft copolymer nanofiber drug-loaded membrane, which is recorded as sample 2.

[0043] Example 3

[0044] The embodiment provides a preparation method of a starch graft copolymer nanofiber drug-loaded film with high antibacterial efficiency, and comprises the following steps:

[0045] (1) Preparation of starch graft copolymer:

[0046] 120 g of high-amylose corn starch is weighed and added to an alcohol-water mixture with a volume ratio of 4:1 to prepare a starch emulsion with a mass fraction of 30%. Dilute hydrochloric acid is used to adjust the pH to 3-4, and the mixture is transferred to a four-necked flask for stirring. After water bath heating to 30 DEG C, nitrogen is introduced for 30 min, and 40 g of hydroxybutyl acrylate, 40 g of (3-acrylamido propyl) trimethylammonium chloride, 0.5% of ferrous ammonium sulfate and 1.0% of hydrogen peroxide solution are simultaneously added to the starch emulsion under nitrogen protection, and the addition is completed within 30-40 min. Then, continuous anaerobic reaction is carried out for 6 hours. The pH of the graft product is adjusted to 6-7 by using 6% sodium carbonate solution, the filter cake is crushed and dried in an oven after washing several times, and is packed for use. The starch graft copolymer is obtained, the molecular structure is shown in Figure 1 The grafting rate of the starch graft copolymer is 27.99%.

[0047] (2) Electrospinning of starch graft copolymer nanofiber drug-loaded film:

[0048] A certain amount of starch graft copolymer prepared in step (1) is weighed, the starch graft copolymer is dissolved in dimethyl sulfoxide, the mass fraction of the starch graft copolymer is 18%, 10% of aspirin by mass of the starch graft copolymer is added, heating is carried out to 70 DEG C, and stirring is carried out by using a magnetic stirrer until the solution becomes transparent. The solution is left to stand until defoaming, and a spinning solution is obtained. The spinning environment temperature of the electrospinning equipment is adjusted to 60 DEG C, the voltage is 20 kV, the distance between the injector and the drum is 15 cm, and the advancing speed is 1 mL / h. The spinning solution is electrospun to obtain a starch graft copolymer nanofiber drug-loaded film, which is recorded as sample 3.

[0049] Comparative example:

[0050] The comparative example provides a preparation method of a starch nanofiber drug-loaded film, and specifically comprises the following steps:

[0051] A certain amount of high-amylose corn starch is weighed, the high-amylose corn starch is dissolved in dimethyl sulfoxide, the mass fraction of the high-amylose corn starch is 18%, 10% of aspirin by mass of the starch is added, heating is carried out to 70 DEG C, and stirring is carried out by using a magnetic stirrer until the solution becomes transparent. The solution is left to stand until defoaming, and a spinning solution is obtained. The spinning environment temperature of the electrospinning equipment is adjusted to 60 DEG C, the voltage is 20 kV, the distance between the injector and the drum is 15 cm, and the advancing speed is 1 mL / h. The spinning solution is electrospun to obtain a starch nanofiber drug-loaded film, which is recorded as sample 0.

[0052] Performance testing:

[0053] 1. SEM morphological characterization:

[0054] SEM (Surface Electroscopy) can observe the morphology and structure of drug-loaded nanofiber membranes, including fiber shape, size, and arrangement. SEM analysis of electrospun nanofiber drug-loaded membranes provides a direct understanding of fiber morphology, allowing for the assessment of fiber uniformity, density, and arrangement, thus providing a morphological basis for subsequent performance testing and applications. Figure 2 The images show SEM images of the drug-loaded nanofiber membranes (sample 0, sample 1, sample 2, and sample 3) prepared using high amylose and three starch graft copolymers, respectively. Figure 2 It can be seen that the nanofiber surfaces of the four drug-loaded membranes are basically smooth with no obvious polymer particle residue, indicating that the high amylose and the three starch graft copolymers are all compatible with aspirin.

[0055] 2. Drug sustained-release performance test:

[0056] Generally speaking, in order to treat some chronic diseases that are difficult to cure in one treatment, such as cardiovascular diseases, cancer, and diabetes, nanofiber drug-loaded membranes with a low sustained-release rate will be the best choice to achieve long-term drug release and continuous drug administration.

[0057] 2.1 Preparation of phosphate (PBS) sustained-release solution: Weigh 8.0g NaCl, 0.2g KCl, 1.44g Na2HPO4 and 0.24g KH2PO4 and dissolve them in 800mL distilled water. Adjust the solution to 7.4 with HCl and finally add distilled water to make up to 1L to obtain a 0.01mol / L PBS sustained-release solution.

[0058] 2.2 Plotting the Aspirin Standard Curve: Appropriate amounts of aspirin were weighed and dissolved in PBS sustained-release solution to obtain standard solutions of 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, and 35 mg / L, respectively. The absorbance of these standard solutions was measured across the entire wavelength range using a UV spectrophotometer. The absorbance was then measured at 296 nm. The absorbance was plotted on the y-axis, and the aspirin solution concentration on the x-axis to plot the aspirin standard curve. Figure 3 As shown, by Figure 3 It can be seen that when the concentration of aspirin is in the range of 5–100 mg / L, the absorbance and concentration show a good linear relationship, and the standard curve equation is y = 0.0152x - 0.0233, with a correlation coefficient R. 2 It is 0.9941.

[0059] 2.3 Test the sustained-release performance of the sample: Take 100 mL PBS sustained-release solution, cut and weigh the same mass of sample 1, sample 2, sample 3 and sample 0 nanofiber drug-loaded film, respectively, and place them in the PBS sustained-release solution at 37°C. Take out 6 mL of PBS sustained-release solution at 1 h, 2 h, 3 h, 6 h, 9 h, respectively, and measure the absorbance at 296 nm wavelength on the ultraviolet spectrophotometer. Replace 6 mL of PBS sustained-release solution every time 6 mL of PBS sustained-release solution is taken out. Calculate the cumulative release amount of the drug according to the aspirin standard curve, and then draw the cumulative release rate curve of aspirin drug of the four samples, as shown in Figure 4 .

[0060] 2.4 Analysis of sustained-release performance results: From Figure 4 It can be seen that the cumulative release rate of sample 0 prepared by using high amylose starch is close to 40% after 2 hours, while the cumulative release rate of samples 1, 2 and 3 prepared by using starch graft copolymer is significantly lower than that of sample 0, and the aspirin drug sustained-release rate of sample 3 is the lowest, and the drug release time is the longest. Sample 3 has a large number of positively charged cations, which can have electrostatic adsorption with negatively charged aspirin drugs, thereby hindering the release of aspirin drugs, reducing the cumulative release rate of aspirin, and significantly improving the drug sustained-release effect of the drug-loaded film.

[0061] 3. Porosity test:

[0062] Porosity is an important parameter for measuring wound dressings in actual application. The ideal wound dressing porosity value should be between 60-90% to provide better air permeability and oxygen permeability for the wound.

[0063] 3.1 Porosity test process: Cut 3 cm x 3 cm nanofiber drug-loaded film of sample 1, sample 2, sample 3 and sample 0, respectively, and stand at room temperature to achieve a humidity balance state with the environment to prevent water evaporation or absorption from changing the porosity of the sample. Accurately weigh the cut sample 1, sample 2, sample 3 and sample 0 using an electronic balance, and record it as m0. Place the weighed sample in ethanol solution, soak it completely for 1 h, take out the soaked sample, wipe off the excess solution with a paper towel, and accurately weigh the treated sample again using an electronic balance, and record it as m1. Calculate the porosity (p, %) of the sample using the following formula and draw the porosity graph, as shown in Figure 5 .

[0064]

[0065] 3.2 Porosity result analysis: From Figure 5It can be seen that as the grafting rate increases, the porosity gradually increases, the main reason is that as the grafting rate increases, the average fiber diameter is lower, the specific surface area of the drug-loaded membrane is larger, and the porosity is higher.

[0066] 4. Water contact angle test:

[0067] The water contact angle test can be used to evaluate the surface properties of the nanofiber drug-loaded membrane, which is often used as a drug release system or medical material, and the stability of its surface is crucial to its function and performance. Generally, the drug release rate of hydrophilic nanofiber drug-loaded membrane is faster, on the contrary, appropriately reducing the hydrophilicity is more conducive to reducing the drug release rate to achieve long-term stable release of drug-loaded membrane drugs.

[0068] 4.1 Water contact angle test process: 5x5mm 2 nanofiber drug-loaded membrane samples were cut from sample 1, sample 2, sample 3 and sample 0 respectively, fixed on the edge of the glass slide, adjusted the height of the stage and made the glass slide in a horizontal state, then made the water droplet vertically drop to the center surface of the sample, took the front view when the liquid just contacted the sample, as shown in Figure 6 , and adjusted the baseline to calculate the contact angle of sample 1, sample 2, sample 3 and sample 0.

[0069] 4.2 Water contact angle test results: From Figure 6 It can be seen that the water contact angles of the nanofiber drug-loaded membranes of sample 1, sample 2, sample 3 and sample 0 are all less than 90°, which are 33.94°, 48.91°, 41.41° and 22.62° respectively. With the increase of grafting rate, the water contact angle of the drug-loaded membrane decreases slightly, which is due to the increase of the number of hydrophilic cationic groups with the increase of the grafting rate, which increases the hydrophilicity of the drug-loaded membrane to some extent; In addition, with the increase of grafting rate, the fiber diameter decreases, the specific surface area increases, and the porosity increases, thereby improving the interfacial water adsorption capacity of the nanofiber drug-loaded membrane.

[0070] 5. Swelling performance test:

[0071] Swelling performance test can help evaluate the stability of drug-loaded membrane under different solution conditions. Drug release system may be affected by different solution environments in the human body or environment, such as different pH values, temperatures or solution compositions, etc. By simulating these conditions and testing the swelling performance of the drug-loaded membrane, its stability and reliability in actual application can be evaluated.

[0072] 5.1 Swelling property test process: Sample 1, Sample 2, Sample 3 and Sample 0 were cut into 2cm x 2cm size, and placed at 25℃, 65% relative humidity for 24 hours. The weights of Sample 1, Sample 2, Sample 3 and Sample 0 were measured and recorded as m0. Sample 1, Sample 2, Sample 3 and Sample 0 were placed in PBS buffer solution with 40 times of their own mass, and placed in a 37℃ oven for 24 hours to reach saturation state. After 30 seconds of static suspension, the wet weights of Sample 1, Sample 2, Sample 3 and Sample 0 were measured and recorded as m1. The swelling rates of Sample 1, Sample 2, Sample 3 and Sample 0 were calculated according to the following formula, and the swelling rate graph was drawn as shown in Figure 7

[0073]

[0074] 5.2 Swelling property test results: It can be seen from Figure 7 that with the increase of grafting rate, the swelling rate of the drug-loaded film shows a gradually increasing trend. The reason is that the introduction of two kinds of grafting monomer units makes the starch show hydrophilic characteristics, thereby increasing the hydrophilicity and the bonding between starch and water molecules, which increases the swelling rate of the drug-loaded film.

[0075] 6. Water vapor transmission rate test:

[0076] The purpose of testing the water vapor transmission rate of the nanofiber drug-loaded film is to evaluate its air permeability in the application process. The water vapor transmission rate refers to the rate of water vapor passing through the material per unit time, which is one of the important indicators for measuring the air permeability of the material. The air permeability can affect the release rate and release behavior of the drug in the drug-loaded film, and further affect the efficacy and therapeutic effect of the drug.

[0077] 6.1 Water vapor transmission rate test process: 10 mL of phosphate buffer was placed in a cylindrical glass bottle. Sample 1, Sample 2, Sample 3 and Sample 0 were cut into a size equal to the cross-sectional area of the container mouth (S). The container mouth was covered with the drug-loaded film and then sealed with adhesive tape and weighed as m0. An open glass bottle containing 10 mL of phosphate buffer was used as a blank control group. Then, the whole device was placed in a 37℃ oven to maintain a relatively low humidity condition. The weight was measured every hour and recorded as m n , a total of twice. The water vapor transmission rates of Sample 1, Sample 2, Sample 3 and Sample 0 were calculated according to the following formula, and the transmission rate graph was drawn as shown in Figure 8

[0078]

[0079] wherein: T is the time interval between the two weight reductions, S is the area of the glass bottle mouth (0.000706 m​​2 )。

[0080] 6.2 Water vapor transmission rate test results: from Figure 8 It can be seen that the water vapor transmission rate decreases first and then increases with the increase of the grafting rate of starch graft copolymer, because the porosity and the water vapor transmission rate are positively correlated, that is, the higher the porosity, the faster the rate of water vapor passing through the drug-loaded film per unit time.

[0081] 7. Antibacterial performance test:

[0082] 7.1 Bacterial culture: a sufficient amount of bacteria was scraped with an inoculation loop and placed in a glass tube containing 5 mL of liquid culture solution (Broth). The bacteria were dispersed uniformly by vortexing, and the glass tube was incubated in a constant temperature shaker at 37°C (120 r / min). After 18-24 h of bacterial culture, the bacteria were centrifuged and washed with 5 mL of PBS buffer solution to disperse the bacteria. Finally, 0.1 mL of the uniformly dispersed bacterial / PBS suspension was added to a new glass tube containing Broth and placed in a shaking incubator for continuous incubation at a constant temperature. This was the first generation of bacteria, which was propagated for three generations according to the above method. The inoculation concentration of E. coli bacteria was 5.7 x 10 6 CFU / sample, and the inoculation concentration of S. aureus bacteria was 2.5 x 10 6 CFU / sample.

[0083] 7.2 Antibacterial performance test process: sample 0 and sample 3 were cut into 2.5 cm x 2.5 cm, and the samples were placed on the surface of the culture dish of the sterile operation platform. 25 μL of the pre-cultured bacterial suspension was added dropwise, respectively. Another piece of sample was placed on top to ensure that the bacterial solution was in full contact with the sample. After 5 min, the two pieces of sample were placed in 5 mL of PBS buffer solution, and the solution was vortexed for 10 s. Then, 100 mmol / L PBS buffer solution was used for continuous dilution, and the diluted solution was uniformly added to the surface of the solid culture dish. After 24 h of incubation in a constant temperature incubator at 37°C, the number of bacterial colonies was determined, and the antibacterial rate was calculated. The blank sample was operated in the same way as the experimental sample. The antibacterial rate of the sample was calculated using the following formula:

[0084]

[0085] In the formula, N1 is the number of bacterial colonies of the sample (pieces); and N0 is the number of bacterial colonies of the blank sample (pieces).

[0086] 7.3 Antibacterial performance test results: the antibacterial effects of sample 0 and sample 3 are shown in Figure 9 、 Figure 10 It can be seen that the drug-loaded film prepared directly from high amylose corn starch (sample 0) has very poor antibacterial properties Figure 9a、 Figure 10 a), while the drug-loaded film prepared from the grafted starch graft copolymer (sample 3) has excellent antibacterial performance, and the inhibition rates of the two bacteria are both substantially 100% (b). Figure 9 b, Figure 10 b), the reason is that the starch graft copolymer contains a large number of positively charged cationic (3-acrylamidopropyl) trimethylammonium chloride monomer units, and the positively charged cationic monomer units can produce strong electrostatic action with the negatively charged anion sites on the bacterial cell wall, resulting in cell lysis and death, so that the drug-loaded film has high antibacterial effect.

[0087] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the protection scope of the present application.

Claims

1. A method for preparing high efficient antibacterial starch graft copolymer nanofiber drug-loaded membrane, characterized in that, The method comprises the following steps: (1) preparing starch graft copolymer: high straight-chain corn starch is added into an alcohol-water mixture to prepare starch milk, the pH of the starch milk is adjusted to 3-4, under nitrogen protection, hydroxybutyl acrylate, (3-acrylamide propyl) trimethyl ammonium chloride, aqueous ferrous ammonium sulfate solution and aqueous hydrogen peroxide solution are simultaneously added into the starch milk within 30-40 min, continuous anaerobic reaction is carried out at 30-40℃ for 4-6 hours, the pH value is adjusted to 6-7, the filter cake is extracted, washed, crushed and dried to obtain starch graft copolymer; (2) electrospinning starch graft copolymer nanofiber drug-loaded film: the starch graft copolymer prepared in step (1) is dissolved in a polar organic solvent to form a starch graft copolymer solution, a drug to be loaded is added into the starch graft copolymer solution, heated to 50-90℃ and stirred until the solution becomes transparent to obtain a spinning solution, and the spinning solution is electrospun to obtain a starch graft copolymer nanofiber drug-loaded film.

2. The method of claim 1, wherein the method of preparing the high efficient anti-bacterial starch graft copolymer nanofiber drug-loaded membrane is characterized by: The volume ratio of alcohol to water in the alcohol-water mixture is (3-5):

1.

3. The method of claim 1, wherein the method of preparation of high efficient anti-microbial starch grafted copolymer nanofiber drug loaded membrane is characterized by: The mass fraction of the starch milk is 20-40%.

4. The method of claim 1, wherein the method of preparation of high efficient anti-microbial starch grafted copolymer nanofiber drug loaded membrane is characterized by: The mass fraction of the aqueous ferrous ammonium sulfate solution is 0.5%, and the mass fraction of the aqueous hydrogen peroxide solution is 0.1%.

5. The method of claim 1, wherein the method of preparation of high efficient anti-microbial starch grafted copolymer nanofiber drug loaded membrane is characterized by: The organic solvent in step (2) is dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, pyridine or chloroform.

6. The method of claim 1, wherein the method of preparation of high efficient anti-microbial starch grafted copolymer nanofiber drug loaded membrane is characterized by: The drug to be loaded in step (2) is a drug that needs to be released, and the addition amount of the drug to be loaded is 8-15% of the mass of the starch graft copolymer.

7. The method of claim 6, wherein the method of preparation of high efficient anti-microbial starch grafted copolymer nanofiber drug loaded membrane is characterized by: The drug to be loaded is aspirin, ibuprofen, acetaminophen, benorylate or indomethacin.

8. The use of the high-efficiency antibacterial starch graft copolymer nanofiber drug-loaded film prepared by the method in any one of claims 1-7 in the preparation of a sustained-release drug or medical material.

9. Use according to claim 8, wherein: The sustained-release drug includes a drug for anti-inflammatory, analgesic, antipyretic or chronic disease treatment, and the medical material includes an external sustained-release drug dressing.

Images