SUSTAINED-RELEASE ANTIBACTERIAL FILM AND PREPARATION METHOD THEREOF

Abstract

A method for preparing a sustained release antibacterial film includes: (1) mixing a cyclodextrin metal-organic framework (CD-MOF) material with a silver nitrate short-chain alcohol solution to prepare an intermediate material A; (2) mixing the intermediate material A with a caffeic acid short-chain alcohol solution to prepare an intermediate material B; (3) dispersing the intermediate material B in a solvent, adding a polydimethylsiloxane main agent and a PDMS auxiliary agent in sequence, and mixing well by stirring to obtain a casting solution; and (4) coating the casting solution on a film support material, conducting vacuum drying, and peeling off a film from the film support material to obtain the sustained-release antibacterial film. A mixed matrix-based film material in which the CD-MOF and the PDMS are physically blended is prepared based on CD-MOF and PDMS for the first time, and may be used in application researches of food, environment and other fields.

Claims

1. A method for preparing a sustained-release antibacterial film, comprising the following steps: (1) mixing a cyclodextrin metal-organic framework (CD-MOF) material with a silver nitrate short-chain alcohol solution to prepare a nano-silver-loaded CD-MOF material, which is recorded as an intermediate material A; (2) mixing the intermediate material A with a caffeic acid short-chain alcohol solution to prepare a CD-MOF material loaded with nano-silver and caffeic acid, which is recorded as an intermediate material B; (3) dispersing the intermediate material B in a solvent, adding a polydimethylsiloxane (PDMS) prepolymer, adding a PDMS crosslinking agent after mixing, and mixing well by stirring to obtain a casting solution; and (4) coating the casting solution on a film support material, conducting vacuum drying, and peeling off a film from the film support material to obtain the sustained-release antibacterial film.

2. The method according to claim 1, wherein in step (1), a concentration of the silver nitrate short-chain alcohol solution is 0.5 mM to 10 mM; a ratio of the CD-MOF and the silver nitrate in the silver nitrate short-chain alcohol solution is 100 mg: (0.0025-0.05) mmol; and a time of the mixing is 10 h to 15 h.

3. The method according to claim 1, wherein in step (2), a concentration of caffeic acid in the caffeic acid short-chain alcohol solution is 5 mg/mL to 10 mg/mL; a mass ratio of the intermediate material A and the caffeic acid in the caffeic acid short-chain alcohol solution is 1:(0.5-1.5); and a time of the mixing is 12 h to 18 h.

4. The method according to claim 1, wherein in step (1) and step (2), the short-chain alcohol is anhydrous methanol or anhydrous ethanol.

5. The method according to claim 1, wherein in step (3), the solvent is selected from the group consisting of acetonitrile, n-hexane, and n-heptane; the intermediate material B is dispersed in the solvent at 5 mg/mL to 10 mg/mL; and the intermediate material B is added at 2.5% to 20% of a total mass of an obtained mixture.

6. The method according to claim 1, wherein in step (3), the PDMS prepolymer comprises a poly(dimethyl-methylvinylsiloxane) prepolymer and a trace amount of a platinum catalyst; the PDMS crosslinking agent comprises a prepolymer with a vinyl side chain and a crosslinking agent poly(dimethyl-methylhydrogenosiloxane); and a mass ratio of the PDMS prepolymer and the PDMS crosslinking agent is 10:1.

7. The method according to claim 1, wherein in step (3), a time of the mixing well by stirring after adding the PDMS crosslinking agent is 8 h to 12 h.

8. The method according to claim 1, wherein in step (4), the film support material is selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, and polyethersulfone resin; a coating thickness is 50 ?m to 300 ?m; and the vacuum drying is conducted at 85? C. to 95? C. for 3 h to 5 h.

9. The method according to claim 1, wherein step (1) and step (2) each comprise a post-treatment after the mixing, that is, the post-treatment comprises conducting centrifugation on a reaction solution, discarding a supernatant, and conducting vacuum drying.

10. The method according to claim 1, wherein a method for preparing the CD-MOF material comprises the following steps: ultrasonic mixing an aqueous solution dispersed with ?-cyclodextrin and potassium hydroxide and conducting a reaction in a water bath to obtain mixed solution, conducting an ultrasonic treatment on the mixed solution while adding polyethylene glycol to the mixed solution after the reaction in the water bath is completed, to obtain a crude product; and washing and drying the crude product to obtain the CD-MOF material; wherein in the aqueous solution, a molar ratio of the ?-cyclodextrin and the potassium hydroxide is 1: (5-10); a molecular weight of the polyethylene glycol is 8,000, and a molar ratio of the polyethylene glycol and the ?-cyclodextrin is (0.06-0.07):1; and a temperature of the reaction in the water bath is 55? C. to 65? C.

11. A sustained-release antibacterial film prepared by the preparation method according to claim 1.

12. Use of the sustained-release antibacterial film according to claim 11 in the fields of food and environment.

13. The method according to claim 2, wherein in step (1) and step (2), the short-chain alcohol is anhydrous methanol or anhydrous ethanol.

14. The method according to claim 3, wherein in step (1) and step (2), the short-chain alcohol is anhydrous methanol or anhydrous ethanol.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a physical image of a compound 2 in Example 1;

[0032] FIG. 2 is a scanning electron microscope (SEM) image of the compound 2 in Example 1;

[0033] FIG. 3 shows infrared spectra of the compound 2 based on different mass fractions of a compound 1;

[0034] FIG. 4 shows an X-ray diffraction (XRD) pattern of the compound 2 in Example 1;

[0035] FIG. 5 shows an effect of the addition of different mass fractions of the compound 1 on an elongation at break of the compound 2;

[0036] FIG. 6 shows an effect of the addition of different mass fractions of the compound 1 on an elastic modulus of the compound 2;

[0037] FIG. 7 shows an effect of the addition of different mass fractions of the compound 1 on a swelling degree in water of the compound 2;

[0038] FIG. 8 shows concentration of the caffeic acid in a release solution after the compound 2 in Example 1 is released in different solvents for 48 h;

[0039] FIG. 9 shows concentration of the silver ion in a release solution after the compound 2 in Example 1 is released in different solvents for 48 h;

[0040] FIG. 10 shows a cumulative release rate of the compound 1 in Example 1 to the caffeic acid in water;

[0041] FIG. 11 shows a cumulative release rate of the compound 1 in Example 1 to the silver ions in water;

[0042] FIG. 12 shows a cumulative release rate of the compound 2 in Example 1 to the caffeic acid in water;

[0043] FIG. 13 shows a cumulative release rate of the compound 2 in Example 1 to the silver ions in water;

[0044] FIG. 14 is a SEM image of the compound 2 in Example 1 after being soaked in water for 48 h;

[0045] FIG. 15 shows a bactericidal lethal curve of the compound 2 in Example 1 to Escherichia co/i 0157:H7 in water; and

[0046] FIG. 16 shows a bactericidal lethal curve of the compound 2 in Example 1 to Staphylococcus aureus in water.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The following clearly and completely describes the technical solutions of the present disclosure with reference to accompanying embodiments. Apparently, the described embodiments are merely some rather than all of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts should fall within the protection scope of the present disclosure.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present disclosure. The terms used in the specification of the present disclosure are merely for the purpose of describing specific embodiments, rather than to limit the present disclosure.

[0049] The present disclosure provides a mixed matrix-based film material based on physical blending for the first time. A CD-MOF material is added to a short-chain alcohol solution containing silver nitrate, and subjected to light-proof vibration to obtain a nano-silver-loaded CD-MOF, recorded as an intermediate material A. The nano-silver-loaded CD-MOF is added to a short-chain alcohol solution containing caffeic acid, and subjected to agitation and incubation in the dark to obtain a CD-MOF compound 1 loaded with caffeic acid and nano-silver, recorded as an intermediate material B. The compound 1 is placed in an acetonitrile solution of a PDMS main agent and stirred, added with a PDMS auxiliary agent, and vacuum drying is conducted to obtain a water-responsive sustained-release antibacterial film based on the CD-MOF material and the PDMS, namely a compound 2; where the PDMS main agent is a PDMS prepolymer, and the PDMS auxiliary agent is a PDMS crosslinking agent.

[0050] In an embodiment, the influence of different reaction conditions on the loading of nano-silver is compared during the preparation of loading silver. The preferred preparation conditions are: a concentration of silver nitrate in the silver nitrate ethanol solution is 2.5 mM to 7.5 mM, and a mass molar ratio of the CD-MOF material and the silver nitrate is 100 mg: (0.0125-0.0375) mmol. A time of the reaction is 10 h to 15 h.

[0051] Under comprehensive consideration, during loading the nano-silver, optimal preparation conditions are: a concentration of silver nitrate in the silver nitrate ethanol solution is 7.5 mM, and a mass molar ratio of the CD-MOF material and the silver nitrate is 100 mg: 0.0375 mmol. A time of the reaction is 12 h.

[0052] In an embodiment, during the preparation of loading caffeic acid, the influence of different reaction conditions on the loading of caffeic acid is compared. The preferred preparation conditions are: a concentration of caffeic acid in the caffeic acid ethanol solution is 5 mg/mL to 10 mg/mL. A mass ratio of the CD-MOF material (intermediate material A) loaded with nano-silver and the caffeic acid is 1:(0.5-1). A time of the mixing is 12 h to 18 h.

[0053] Under comprehensive consideration, optimal preparation conditions are: a concentration of caffeic acid in the caffeic acid ethanol solution is 8 mg/mL, a mass ratio of the CD-MOF material loaded with nano-silver and the caffeic acid is 1:0.8. A time of the mixing is 15 h.

[0054] In an embodiment, the compound 1 (intermediate material B) prepared under optimal conditions (the loading of nano-silver and the loading of caffeic acid each are conducted under optimal conditions) are used as a raw material, and mechanical properties (elongation at break and elastic modulus) and swelling degree in water of the compound 2 with different contents of the compound 1 (intermediate material B) are investigated: adding different mass fractions of nano-silver and caffeic acid-loaded CD-MOF (CA@Ag@CD-MOF) into an acetonitrile, n-hexane or n-heptane solution containing a PDMS matrix (including the PDMS main agent and the PDMS auxiliary agent) (a proportion of the compound 1 (intermediate material B) added is 2.5 wt %, 5 wt %, 10 wt %, 15 wt %, and 20 wt % of a total mass of the reaction solution, respectively), stirring for several hours, drying overnight and vacuumizing, and conducting a reaction at 90? C. for several hours under vacuum, to obtain a mixed matrix-based film (CA@Ag@CD-MOF/PDMS).

[0055] In this specific embodiment, the PDMS is a purchased commercial reagent produced by Dow Corning in the United States. The PDMS includes two components: a prepolymer A (PDMS main agent) and a crosslinking agent B (PDMS auxiliary agent). The prepolymer A includes mainly a poly(dimethyl-methylvinylsiloxane) prepolymer and a trace amount of a platinum catalyst. The crosslinking agent B includes a prepolymer with a vinyl side chain and a crosslinking agent poly(dimethyl-methylhydrogenosiloxane). After the PDMS main agent is dispersed evenly in the solution, the PDMS auxiliary agent is added to make a crosslinking reaction evenly conducted in the solution. A mass ratio of the main agent and the auxiliary agent is 10:1.

[0056] The elongation at break, elastic modulus and swelling degree in water of the mixed matrix-based films prepared with different mass fractions of the CD-MOF (CA@Ag@CD-MOF) are shown in FIG. 5, FIG. 6, and FIG. 7 respectively.

[0057] The results in FIG. 5 show that the addition of CD-MOF (CA@Ag@CD-MOF) basically does not affect the elongation at break, and the more preferred addition amount has a better elongation at break than that without addition. The results in FIG. 6 show that the addition of CD-MOF (CA@Ag@CD-MOF) can increase the elastic modulus of the film, where the elastic modulus has an ideal increase at 10% to 20% and a maximum increase at 15%.

[0058] The results in FIG. 7 show that the addition of CD-MOF (CA@Ag@CD-MOF) can significantly increase the swelling degree of the film; with the increase of the addition amount of CD-MOF (CA@Ag@CD-MOF), the swelling degree of the film gradually increases, and reaches about 40% at the addition amount of 15%.

[0059] The following is an example of the optimal reaction conditions:

Example 1

[0060] (1) ?-cyclodextrin (648 mg, 0.5 mmol), potassium hydroxide (256 mg, 4.56 mmol), and ultrapure water (20 mL) were added to a beaker, stirred at room temperature and filtered with a 0.45 ?m aqueous filter membrane to obtain a solution 1; [0061] (2) methanol (12 mL) was placed in an ultrasonic tube in advance, then the solution 1 was placed in the ultrasonic tube to form a milky white solution 2. The ultrasonic tube was placed into a water bath at 60? C., and allowed to stand for 15 min to obtain a clear and transparent solution 3; [0062] (3) the solution 3 was subjected to ultrasonic treatment, and polyethylene glycol (8000) (256 mg) was added rapidly after the ultrasonic treatment was started, and a crude product was obtained after the reaction was completed; [0063] (4) the crude product was transferred from the ultrasonic tube to the beaker, and allowed to stand for 1 h to obtain a precipitate, the precipitate was washed three times with methanol by centrifugation, and after centrifugal separation, a new precipitate was dispersed in the methanol; [0064] (5) a centrifuged product was put into a vacuum drying oven, dried at 50? C. for 12 h under vacuum conditions, and cooled to room temperature to obtain a CD-MOF material; [0065] (6) 100 mg of the CD-MOF material was added into 5 mL of silver nitrate ethanol solution with a concentration of 7.5 mM, and incubated at 37? C. and 180 rpm for 12 h by shaking in a shaker in the dark; [0066] (7) an incubated solution was centrifuged twice at 5,000 rpm, a supernatant was discarded, and a residual solvent was dried with a filter paper to obtain a precipitate; the precipitate was vacuum-dried at 50? C. for 5 h to obtain a CD-MOF loaded with nano-silver; [0067] (8) 50 mg of the CD-MOF loaded with nano-silver was added into 50 mL of caffeic acid ethanol solution with a concentration of 8 mg/mL, and incubated at room temperature and 180 rpm for 15 h by magnetic stirring in the dark; [0068] (7) an incubated solution was centrifuged at 5,000 rpm, a supernatant was discarded, and a residual solvent was dried with a filter paper to obtain a precipitate; the precipitate was vacuum-dried at 50? C. for 5 h to obtain a CD-MOF compound 1 loaded with caffeic acid and nano-silver, namely an intermediate material B; [0069] (8) 533 mg of the compound 1 was added into 75 mL of acetonitrile and stirred evenly, 0.3 mL of a PDMS main agent (in the reaction system, the mass fraction of the compound 1 (intermediate material B) was 15 wt %) was added and stirred evenly, then 0.03 mL of PDMS auxiliary agent was added; a mixed solution was mixed well by stirring for about 10 h, poured on a 12 mm polytetrafluoroethylene petri dish in diameter, the mixed solution was levelled, and dried at room temperature overnight; and [0070] (9) the polytetrafluoroethylene petri dish was vacuum-dried at 90? C. for 4 h, a prepared product was gently scraped off with a scraper, washed with ethanol, and dried to obtain a compound 2.

[0071] A physical image of the compound 2 synthesized in this example is shown in FIG. 1, with desirable toughness and a dark brown surface, which are caused by the deposition of nano-silver in the compound 1. The infrared spectra of compound 1 and compound 2 are shown in FIG. 3: with the increase of the addition amount of compound 1, characteristic peaks of the compound 1 at 3400 cm.sup.?1 and 1(40 cm.sup.?1 of the compound 2 gradually become stronger; compared with the PDMS, the compound 2 does not produce new characteristic peaks, indicating that there is no chemical interaction between the PDMS and the compound 1. The powder XRD patterns of compound 1 and compound 2 are shown in FIG. 4: a peak position in the XRD pattern of the compound 2 is consistent with that of the compound 1, compared with an amorphous pattern of the PDMS, the compound 2 has certain crystalline characteristic peaks, indicating the successful incorporation of the compound 1.

[0072] The concentration of the caffeic acid in the release solution after the compound 2 is released in different solvents for 48 h are shown in FIG. 8: the caffeic acid concentration of the compound 2 released in water is much greater than that of the organic solvent. The concentration of the silver ion in the release solution after the compound 2 is released in different solvents for 48 h are shown in FIG. 9: the silver ion concentration of the compound 2 released in water is much greater than that of the organic solvent. This indicated that the compound 2 have better responsiveness to water conditions.

[0073] The cumulative release rate of the compound 1 to caffeic acid in water is shown in FIG. 10: the compound 1 forms a burst release of caffeic acid in about 1 min. The cumulative release rate of the compound 1 to silver ions in water is shown in FIG. 11: the compound 1 forms a burst release of silver ions in about 1 min, indicating that the compound 1 disintegrate rapidly in water, resulting in the rapid release of the loaded substance. The cumulative release rate of the compound 2 to caffeic acid in water is shown in FIG. 12: the compound 2 can achieve sustained-release of the caffeic acid within 96 h. The cumulative release rate of the compound 2 to silver ions in water is shown in FIG. 13: the compound 2 can achieve sustained-release of the silver ions within 96 h, indicating that the compound 2 can protect the CD-MOF from disintegration in water, to realize sustained-release of the loaded substance.

[0074] The bactericidal lethal curve of the compound 2 to Escherichia coli 0157:H7 in water is shown in FIG. 15: the compound 2 can achieve a 7 logarithmic lethal effect on the Escherichia coli 0157:H7 within 12 h. The bactericidal lethal curve of the compound 2 to Staphylococcus aureus in water is shown in FIG. 16: the compound 2 can achieve a 7 logarithmic lethal effect on the Staphylococcus aureus within 36 h.

[0075] The SEM image of a cross-section of the compound 2 synthesized in this example is shown in FIG. 2: it is clearly seen that the compound 1 is embedded inside the film. The SEM image of the cross-section of the compound 2 after soaking in water for 48 h is shown in FIG. 14: it is clearly seen that the compound 1 falls off from the film and disintegrates to form pores after soaking in water. This indicates that compound 2 can achieve a release function in water.

[0076] The above only specifically and in detail describes several embodiments of the present disclosure, but they should not therefore be construed as limiting the scope of the present disclosure. It should be noted that those of ordinary skill in the art can further make variations and improvements without departing from the conception of the present disclosure. These variations and improvements all fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope defined by the claims.