CN114182435B - Polylactic acid antibacterial composite fiber membrane and preparation method and application thereof - Google Patents

Abstract

The invention provides a polylactic acid antibacterial composite fiber membrane and a preparation method and application thereof, belonging to the technical field of antibacterial materials and comprising the following steps: mixing the silver source with tea polyphenol and water, and carrying out reduction reaction to obtain a composite antibacterial agent; mixing the composite antibacterial agent with polylactic acid, a solvent and a coupling agent to obtain a skin layer spinning solution; mixing polylactic acid and a solvent to obtain a core layer spinning solution; and (3) carrying out coaxial electrostatic spinning on the skin layer spinning solution and the core layer spinning solution to obtain the polylactic acid antibacterial composite fiber membrane. The invention firstly adopts a tea polyphenol biological reduction method to prepare the composite antibacterial agent, improves the antibacterial performance of the composite fiber membrane, adopts coaxial electrostatic spinning to prepare the skin-core composite fiber membrane and improves the mechanical performance of the composite fiber membrane. The results of the examples show that the antibacterial rate of the polylactic acid antibacterial composite fiber membrane prepared by the invention on escherichia coli reaches 99.32%, and the breaking strength reaches 53cN.

Description

A kind of polylactic acid antibacterial composite fiber film and its preparation method and application

technical field

The invention relates to the technical field of antibacterial materials, in particular to a polylactic acid antibacterial composite fiber membrane and its preparation method and application.

Background technique

With the development of social industry, the impurities and bacteria in the air will increase, which will cause harm to human health. Polylactic acid has good biocompatibility, mechanical properties and biodegradability, and is an environmentally friendly and sustainable material. However, polylactic acid materials do not have antibacterial properties. In order to improve the antibacterial properties of polylactic acid materials and reduce the harm of bacteria to the human body, it is generally necessary to add antibacterial agents.

The commonly used antibacterial agent is nano-silver particles at present, but adding nano-silver to the improvement of the antibacterial performance of polylactic acid is relatively limited. In the prior art, such as the patent of invention with publication number CN108914375A, nano-silver is added to polylactic acid, and the composite material has no effect on Escherichia coli. The highest antibacterial rate is only 95%.

Therefore, how to further improve the antibacterial properties of polylactic acid has become a difficult problem in the prior art.

Contents of the invention

In view of this, the object of the present invention is to provide a polylactic acid antibacterial composite fiber membrane and its preparation method and application. The polylactic acid antibacterial composite fiber membrane prepared by the invention has excellent antibacterial performance.

In order to realize the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a kind of preparation method of polylactic acid antibacterial composite fiber membrane, comprises the following steps:

(1) Silver source is mixed with tea polyphenols and water, and reduction reaction is carried out to obtain composite antibacterial agent;

(2) the composite antibacterial agent that described step (1) is obtained is mixed with polylactic acid, solvent and coupling agent, obtains cortex spinning solution;

(3) mixing polylactic acid with a solvent to obtain a core spinning solution;

(4) coaxial electrospinning is carried out by the cortex spinning liquid that described step (2) obtains and the core layer spinning liquid that described step (3) obtains, obtains polylactic acid antibacterial composite fiber film;

The steps (1) and (3) are not in sequence.

Preferably, the ratio of the amount of tea polyphenols to the silver source in the step (1) is (1-1.5):1.

Preferably, the solvent in step (2) and step (3) includes N,N-dimethylformamide and dichloromethane.

Preferably, the mass ratio of dichloromethane to N,N-dimethylformamide is (2-3):1.

Preferably, the mass concentration of polylactic acid in the skin spinning solution in step (2) is 4-6%.

Preferably, the mass ratio of the composite antibacterial agent to polylactic acid in the step (2) is (0.5-3):5.

Preferably, the coupling agent in the step (2) includes a silane coupling agent; the mass ratio of the coupling agent to the composite antibacterial agent is (0.05-0.2):1.

Preferably, the spinning voltage of the coaxial electrospinning in the step (4) is 14-16kV; the spinning distance of the coaxial electrospinning is 8-14cm; The propulsion speed of the layer spinning solution is independently 1-2 mL/h.

The invention provides the polylactic acid antibacterial composite fiber membrane prepared by the preparation method described in the above technical solution.

The present invention also provides the application of the polylactic acid antibacterial composite fiber membrane described in the above technical solution in the field of antibacterial.

The invention provides a preparation method of a polylactic acid antibacterial composite fiber membrane, comprising the following steps: mixing a silver source with tea polyphenols and water, performing a reduction reaction to obtain a composite antibacterial agent; combining the obtained composite antibacterial agent with polylactic acid, The solvent and the coupling agent are mixed to obtain the skin layer spinning solution; the polylactic acid is mixed with the solvent to obtain the core layer spinning solution; the obtained cortex spinning solution and the core layer spinning solution are subjected to coaxial electrospinning to obtain polylactic acid Antibacterial composite fiber membrane. The present invention first uses tea polyphenols to biologically reduce silver sources to prepare nano-silver composite antibacterial agents, which have excellent antibacterial properties and can improve the antibacterial properties of fiber membranes; at the same time, coaxial electrospinning is used to prepare skin-core composite fiber membranes to improve mechanical properties. The results of the examples show that the polylactic acid antibacterial composite fiber membrane prepared by the present invention has a bacteriostatic rate of 99.32% against Escherichia coli and a breaking strength of 53 cN.

Description of drawings

Fig. 1 is the scanning electron micrograph under the magnification of 3000 times of the fibrous membrane prepared in Example 1 of the present invention;

Fig. 2 is the scanning electron micrograph under the magnification of 5000 magnifications of the fiber film prepared in Example 1 of the present invention;

Fig. 3 is the scanning electron micrograph of the fibrous film prepared in comparative example 2 of the present invention;

Fig. 4 is the scanning electron micrograph of the fiber film prepared in comparative example 3 of the present invention;

Fig. 5 is the scanning electron micrograph under the magnification of 3000 magnifications of the fiber film prepared in comparative example 1 of the present invention;

Fig. 6 is the scanning electron micrograph under the magnification of 5000 magnifications of the fiber film prepared in comparative example 1 of the present invention;

Fig. 7 is the scanning electron micrograph of the fiber membrane prepared in Example 2 of the present invention;

Figure 8 is a scanning electron micrograph of the fiber membrane prepared in Example 3 of the present invention;

Figure 9 is a scanning electron micrograph of the fiber membrane prepared in Example 4 of the present invention;

Figure 10 is a scanning electron micrograph of the fiber membrane prepared in Example 5 of the present invention;

Fig. 11 is the infrared spectrogram of the fiber membrane prepared in Examples 2-5 and Comparative Example 1 of the present invention;

Fig. 12 is the XRD pattern of the fiber membrane prepared in Examples 2-5 and Comparative Example 1 of the present invention;

Figure 13 is a diagram of the number of colonies of the fiber membranes prepared in Examples 2 to 5 and Comparative Example 1 of the present invention;

Fig. 14 is a diagram of the mechanical properties of the fiber membranes prepared in Examples 1-4 and Comparative Example 1 of the present invention;

Fig. 15 is the contact angle of the fiber film prepared in Example 3 of the present invention and Comparative Example 1;

Fig. 16 is the XRD pattern of the composite antibacterial agent prepared in Example 1 of the present invention;

Fig. 17 is the ultraviolet-visible absorption spectrogram of the composite antibacterial agent prepared in Example 1 of the present invention;

Figure 18 is a graph showing the number of colonies of the composite antibacterial agent prepared in Example 1 of the present invention.

Detailed ways

The invention provides a kind of preparation method of polylactic acid antibacterial composite fiber membrane, comprises the following steps:

(1) Silver source is mixed with tea polyphenols and water, and reduction reaction is carried out to obtain composite antibacterial agent;

(2) the composite antibacterial agent that described step (1) is obtained is mixed with polylactic acid, solvent and coupling agent, obtains cortex spinning solution;

(3) mixing polylactic acid with a solvent to obtain a core spinning solution;

(4) coaxial electrospinning is carried out by the cortex spinning liquid that described step (2) obtains and the core layer spinning liquid that described step (3) obtains, obtains polylactic acid antibacterial composite fiber film;

The steps (1) and (3) are not in sequence.

Unless otherwise specified, the present invention has no special limitation on the source of each component, and commercially available products well known to those skilled in the art can be used.

The invention mixes the silver source with tea polyphenols and water for reduction reaction to obtain the compound antibacterial agent.

In the present invention, the silver source preferably includes silver nitrate or silver ammonia solution, more preferably silver nitrate.

In the present invention, the ratio of the amount of tea polyphenols to the silver source is preferably (1-1.5): 1, more preferably (1.1-1.4): 1, most preferably (1.2-1.3): 1 . In the present invention, the tea polyphenol is used as reducing agent and stabilizing agent of silver source. The present invention limits the ratio of the amount of tea polyphenols to the silver source within the above range, so that the silver source can be fully reduced to form nano-silver, and the nano-silver can be more uniformly dispersed.

In the present invention, the water is preferably deionized water.

In the present invention, the mixing method of the silver source, tea polyphenols and water is preferably as follows: mix the silver source with part of the water to obtain a silver source solution; mix the tea polyphenols with the remaining part of water to adjust the pH value to obtain tea Polyphenol solution; add the tea polyphenol solution dropwise to the silver source solution. In the present invention, the concentration of the silver source solution is preferably 0.02-0.06 mol/L, more preferably 0.03-0.05 mol/L, most preferably 0.04 mol/L. The present invention limits the concentration of the silver source solution within the above range, which can make the generated nano-silver regular in shape, small in size and narrow in size distribution.

In the present invention, the concentration of the tea polyphenol solution is preferably 0.05-0.06 g/mL; the pH value of the tea polyphenol solution is preferably 8.7-9.3, more preferably 9. In the present invention, the concentration and pH value of the tea polyphenol solution are limited within the above-mentioned range, so that the nano-silver particle size is smaller and the dispersion is relatively uniform. The present invention has no special limitation on the operation of adjusting the pH value of the tea polyphenol solution, as long as the pH value of the tea polyphenol solution is within the above range. The present invention preferably adds sodium hydroxide solution to adjust the pH value of the tea polyphenol solution. The present invention has no special limitation on the concentration and dosage of the sodium hydroxide solution, as long as the pH value of the tea polyphenol solution is within the above range.

In the present invention, the dropping rate is preferably 5-7 mL/min, more preferably 6 mL/min. In the present invention, the dropwise addition can make the particle size of the generated silver nanoparticles smaller and less likely to agglomerate, thereby improving the performance of the product.

In the present invention, the temperature of the reduction reaction is preferably 15-25° C., more preferably 20° C.; the time of the reduction reaction is preferably 1-3 hours, more preferably 2 hours. In the present invention, the temperature and time of the reduction reaction are limited within the above-mentioned range, so that the silver source can fully react to generate nano-silver. In the present invention, during the reduction reaction process, the silver source is reduced to generate nano-silver, and the oxidation products of tea polyphenols and unreacted tea polyphenols are adsorbed on the surface of nano-silver to obtain a composite antibacterial agent.

After the reduction reaction is completed, the present invention preferably freeze-dries the product of the reduction reaction to obtain a composite antibacterial agent.

In the present invention, the freeze-drying temperature is preferably -50-30°C, more preferably -40°C; the freeze-drying time is preferably 12-36h, more preferably 24h.

After obtaining the composite antibacterial agent, the present invention mixes the composite antibacterial agent with polylactic acid, a solvent and a coupling agent to obtain a cortex spinning solution.

In the present invention, the average molecular weight of the polylactic acid is preferably 70,000-90,000, more preferably 80,000. In the present invention, the molecular weight of the polylactic acid is limited within the above range, so that the fiber membrane can have better mechanical properties.

In the present invention, the mass concentration of polylactic acid in the skin spinning solution is preferably 4-6%, more preferably 5%. The present invention limits the mass concentration of polylactic acid in the cortex spinning solution to the above range, which can fully dissolve the polylactic acid, and at the same time make the cortex spinning solution have a relatively suitable viscosity, which is beneficial to the electrospinning.

In the present invention, the mass ratio of the composite antibacterial agent to polylactic acid is preferably (0.5-3):5, more preferably (1-2):5. The present invention limits the mass ratio of the composite antibacterial agent to the polylactic acid within the above range, so that the composite antibacterial agent can be more uniformly dispersed in the polylactic acid, so that the fiber membrane has excellent antibacterial and mechanical properties.

In the present invention, the solvent preferably includes N,N-dimethylformamide and dichloromethane; the mass ratio of the dichloromethane and N,N-dimethylformamide is preferably (2～3): 1, more preferably (2.2-2.8):1, most preferably (2.4-2.6):1. In the present invention, the types of solvents and the mass ratio of the two solvents are limited within the above-mentioned ranges, so that each component can be dissolved more fully.

In the present invention, there is no special limitation on the amount of the solvent used, as long as the mass concentration of polylactic acid in the cortex spinning solution is within the above range.

In the present invention, the coupling agent is preferably a silane coupling agent, more preferably a silane coupling agent KH550 or KH560. In the present invention, the coupling agent can improve the compatibility of the composite antibacterial agent and polylactic acid, and further improve the performance of the fiber membrane.

In the present invention, the mass ratio of the coupling agent to the composite antibacterial agent is preferably (0.05-0.2):1, more preferably 0.1:1. The present invention limits the mass ratio of the coupling agent to the composite antibacterial agent within the above range, which can make the composite antibacterial agent and polylactic acid have better compatibility.

In the present invention, the mixing method of the composite antibacterial agent and polylactic acid, solvent and coupling agent is preferably: mixing the composite antibacterial agent and coupling agent, and ultrasonicating for 0.5 to 1 h under the condition of 400 to 500 W to obtain a mixed solution; Mix polylactic acid and methylene chloride, stir magnetically at 500-800 rpm for 1-3 hours, then add N,N-dimethylformamide, continue stirring for 1-2 hours, add the mixed solution, and continue stirring for 1-3 hours. By adopting the mixing method of the present invention, each component can be dissolved and dispersed more fully.

The invention mixes the polylactic acid and the solvent to obtain the core layer spinning liquid.

In the present invention, the average molecular weight of the polylactic acid is preferably 70,000-90,000, more preferably 80,000. In the present invention, the molecular weight of the polylactic acid is limited within the above range, so that the fiber membrane can have better mechanical properties.

In the present invention, the mass concentration of polylactic acid in the core spinning solution is preferably 4-6%, more preferably 5%. The present invention limits the mass concentration of polylactic acid in the core layer spinning solution to the above range, which can fully dissolve the polylactic acid, and at the same time make the core layer spinning solution have a relatively suitable viscosity, which is beneficial to the electrospinning.

In the present invention, the solvent preferably includes N,N-dimethylformamide and dichloromethane; the mass ratio of the dichloromethane and N,N-dimethylformamide is preferably (2～3): 1, more preferably (2.2-2.8):1, most preferably (2.4-2.6):1. In the present invention, the types of solvents and the mass ratio of the two solvents are limited within the above-mentioned ranges, so that each component can be dissolved more fully.

In the present invention, there is no special limitation on the amount of the solvent used, as long as the mass concentration of polylactic acid in the core layer spinning solution is within the above range.

In the present invention, the mixing method of the polylactic acid and the solvent is preferably: mixing polylactic acid and methylene chloride, stirring magnetically for 1-3 hours at 500-800 rpm, then adding N,N-dimethylformamide, and continuing Stir for 1-2 hours.

After obtaining the skin layer spinning solution and the core layer spinning solution, the present invention carries out coaxial electrospinning on the skin layer spinning solution and the core layer spinning solution to obtain the polylactic acid antibacterial composite fiber membrane.

In the present invention, during the electrospinning process, the skin layer spinning solution and the core layer spinning solution are respectively injected into the syringe, and the electrospinning needle is inserted so that the needle is aligned with the center of the aluminum foil receiving device and is at the same height as the center , the needle is connected to the positive pole of the high-voltage current power supply, the aluminum foil receiving device is grounded, and the electrospinning starts.

In the present invention, the spinning voltage of the coaxial electrospinning is preferably 14-16kV, more preferably 15kV; the spinning distance of the coaxial electrospinning is preferably 8-14cm, more preferably 10-12cm ; During the coaxial electrospinning, the propulsion speeds of the skin spinning liquid and the core spinning liquid are independently preferably 1-2 mL/h, more preferably 1.5 mL/h. In the present invention, the spinning voltage, spinning distance and spinning liquid advancing speed of the coaxial electrospinning are limited within the above-mentioned range, which can make the spinning liquid be fully stretched and split to form fibers, and in the spinning process The medium solvent has a suitable volatilization rate, which makes the fiber diameter more uniform and further improves the performance of the fiber membrane.

The present invention first uses tea polyphenols to biologically reduce silver sources to prepare nano-silver composite antibacterial agents, which have excellent antibacterial properties and can improve the antibacterial properties of fiber membranes; at the same time, coaxial electrospinning is used to prepare skin-core composite fiber membranes to improve Excellent mechanical properties, controlling the dosage of each component and various process parameters, make the composite fiber membrane have excellent antibacterial properties and mechanical properties.

The present invention also provides the polylactic acid antibacterial composite fiber membrane prepared by the preparation method described in the above technical solution.

The polylactic acid antibacterial composite fiber membrane provided by the invention has excellent antibacterial properties and mechanical properties.

The present invention also provides the application of the polylactic acid antibacterial composite fiber membrane described in the above technical solution in the field of antibacterial.

The present invention has no special limitation on the operation of the application of the polylactic acid antibacterial composite fiber membrane in the antibacterial field, and the technical solution for the application of the polylactic acid antibacterial composite fiber membrane in the antibacterial field well known to those skilled in the art can be used.

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

(1) 0.17g silver nitrate is dissolved in 25mL deionized water to obtain a silver nitrate solution of 0.04mol/L;

(2) Dissolve 0.3372g tea polyphenols (the ratio of tea polyphenols to silver nitrate is 1.2:1) in 6mL deionized water, add sodium hydroxide solution to adjust the pH value to 9, and obtain 0.0562g/mL tea polyphenol solution;

(3) The tea polyphenol solution was added dropwise to the silver nitrate solution at a rate of 6mL/min, reacted at 20°C for 2h, and then freeze-dried at -40°C for 24h to obtain the composite antibacterial agent Ag@TP;

(4) Mix the composite antibacterial agent and the coupling agent KH550, and 450W ultrasonic for 30 minutes to obtain a mixed solution (the mass ratio of the coupling agent to the composite antibacterial agent is 0.1:1);

(5) Dissolve polylactic acid (average molecular weight 80,000) in dichloromethane, stir magnetically for 2 hours at 700rpm, then add N,N-dimethylformamide (dichloromethane and N,N-dimethylformamide The mass ratio is 7:3), continue to stir for 1h; add the mixed solution of step (4) (the mass ratio of composite antibacterial agent and polylactic acid is 0.5:5), continue to stir for 2h, and obtain the cortex spinning solution (cortex spinning The mass concentration of polylactic acid in the liquid is 5%);

(6) Dissolve polylactic acid (average molecular weight 80,000) in dichloromethane, stir magnetically for 2 hours at 700rpm, then add N,N-dimethylformamide (dichloromethane and N,N-dimethylformamide The mass ratio is 7:3), continue to stir for 1h, obtain the core layer spinning solution (the mass concentration of polylactic acid in the core layer spinning solution is 5%);

(7) Pour the cortex spinning solution and the core spinning solution into 10mL syringes respectively. The syringes are fixed in the slot of the micro-syringe pump, and the 18G electrospinning needle is inserted, so that the needle is aligned with the center of the aluminum foil receiving device and aligned with the center of the aluminum foil receiving device. The center is at the same height, the needle is connected to the positive pole of the high-voltage current power supply, the aluminum foil receiving device is grounded, and the coaxial electrospinning is started under the conditions of a spinning voltage of 15kV, a spinning distance of 10cm, and a propulsion speed of each spinning solution of 1.5mL/h Silk, to obtain polylactic acid antibacterial composite fiber membrane PLA/Ag@TP-0.5%.

Example 2

The mass ratio of the composite antibacterial agent to polylactic acid in Example 1 was replaced by 1:5, and other parameters were the same as in Example 1 to obtain a polylactic acid antibacterial composite fiber membrane PLA/Ag@TP-1%.

Example 3

The mass ratio of composite antibacterial agent to polylactic acid in Example 1 was replaced with 1.5:5, and other parameters were the same as in Example 1 to obtain a polylactic acid antibacterial composite fiber membrane PLA/Ag@TP-1.5%.

Example 4

The mass ratio of the composite antibacterial agent to polylactic acid in Example 1 was replaced by 2:5, and other parameters were the same as in Example 1 to obtain a polylactic acid antibacterial composite fiber membrane PLA/Ag@TP-2%.

Example 5

The mass ratio of the composite antibacterial agent to polylactic acid in Example 1 was replaced with 3:5, and other parameters were the same as in Example 1 to obtain a polylactic acid antibacterial composite fiber membrane PLA/Ag@TP-3%.

Comparative example 1

(1) Dissolve polylactic acid (average molecular weight 80,000) in dichloromethane, stir magnetically for 2 hours at 700rpm, then add N,N-dimethylformamide (dichloromethane and N,N-dimethylformamide The mass ratio is 7:3), and continue to stir for 1h to obtain an electrospinning solution (the mass concentration of polylactic acid in the electrospinning solution is 5%);

(2) Inject the electrospinning solution into a 10mL syringe, fix the syringe in the slot of the micro-syringe pump, insert the 18G electrospinning needle, align the needle with the center of the aluminum foil receiving device and be at the same height as the center, and connect the needle The positive pole of the high-voltage current power supply, the aluminum foil receiving device is grounded, and the coaxial electrospinning is started under the conditions of a spinning voltage of 15kV, a spinning distance of 10cm, and a spinning solution advancing speed of 1.5mL/h to obtain a pure polylactic acid fiber membrane PLA .

Comparative example 2

The mass ratio of methylene chloride and N,N-dimethylformamide in Example 1 is 6:4, and other parameters are the same as in Example 1.

Comparative example 3

The mass ratio of dichloromethane and N,N-dimethylformamide in Example 1 is 8:2, and other parameters are the same as in Example 1.

Using a scanning electron microscope (S-1800, Hitachi, 15kV), the scanning electron micrographs of the fiber membranes prepared in Example 1, Comparative Example 2 and Comparative Example 3 were tested, and the results are shown in Figures 1-4. Fig. 1 is the scanning electron micrograph of the fiber film prepared by Example 1 under 3000 magnification; Fig. 2 is the scanning electron micrograph of the fiber film prepared by Example 1 under 5000 magnification; Fig. 3 is the scanning electron micrograph of the fiber film prepared by Comparative Example 2 ;

FIG. 4 is a scanning electron micrograph of the fiber membrane prepared in Comparative Example 3. As can be seen from Figures 1 to 4, the fibers on the fiber membrane prepared in Comparative Example 2 are too thin and disorderly to form a film; the fibers on the fiber membrane prepared in Comparative Example 3 are too cohesive and have parallel threads; The fibers on the fiber membrane prepared in Example 1 have no obvious bonding phenomenon, and the fibers are longer; it shows that the solvent ratio in Example 1 is more appropriate.

Using a scanning electron microscope (S-1800, Hitachi, 15kV), the scanning electron micrographs of the fiber membranes prepared in Examples 2-5 and Comparative Example 1 were tested, and the results are shown in Figures 5-10. Fig. 5 is a scanning electron micrograph of the fiber membrane prepared in Comparative Example 1 at 3000 magnifications; Fig. 6 is a scanning electron micrograph of the fiber membrane prepared in Comparative Example 1 at 5000 magnification; Fig. 7 is a scanning electron micrograph of the fiber membrane prepared in Example 2 ; FIG. 8 is a scanning electron microscope image of the fiber membrane prepared in Example 3; FIG. 9 is a scanning electron microscope image of the fiber membrane prepared in Example 4; FIG. 10 is a scanning electron microscope image of the fiber membrane prepared in Example 5. As can be seen from Figures 5 to 10, the surface of the pure polylactic acid fiber prepared in Comparative Example 1 is smooth and has an irregular coherent porous structure; the fiber membrane fiber prepared in Example 2 is relatively messy and has parallel filaments; the prepared fiber in Example 3 The fiber thickness of the fiber membrane is relatively uneven and curled; the fiber thickness of the fiber membrane prepared in Example 4 is uniform and porous, the fiber layers are stacked, and the pores are small; the fiber membrane fiber prepared in Example 5 is thick and uneven; comprehensive Above, the fiber morphology prepared in Example 4 is better.

An infrared spectrometer (TL-8000, American PE Company) was used to test the infrared spectrograms of the fiber membranes prepared in Examples 2-5 and Comparative Example 1, and the results are shown in FIG. 11 . It can be seen from Figure 11 that in the infrared spectrum of the composite fiber membrane, the stretching vibration peaks of the CC of PLA appear at 869cm ^-1 , 1079cm ^-1 and 1181cm ^-1 , 1370cm ^-1 , 1454cm ^-1 , 1754cm ^-1 , COC absorption peak, CH absorption peak, methyl (-CH ₃ ) asymmetrically curved absorption peak and C=O absorption peak, there is also a wider absorption band around 3400cm ^-1 , which is precisely the phenolic hydroxyl group (ArOH ) characteristic absorption peak, indicating that there are phenolic hydroxyl groups in the molecule, and the skeleton structure of tea polyphenols is basically retained; there is a characteristic absorption of carbonyl (-C=O) at 1715cm ^-1 , indicating that the combination of tea polyphenols and metals occurs reaction, and the benzene ring absorption peak appeared at 1617cm ^-1 , indicating that the composite antibacterial agent was loaded on the PLA fiber membrane; with the increase of the content of the composite antibacterial agent, it can be seen that the stretching vibration absorption peak of COH at 1037cm ^-1 gradually strengthened; To sum up, it can be seen that the composite fiber membrane made of PLA as the carrier and Ag@TP as the antibacterial agent is well compounded through the combination of valence bonds.

The XRD patterns of the fiber membranes prepared in Examples 2-5 and Comparative Example 1 were tested by XRD (TD-3700 type, Dandong Tongda Technology Co., Ltd., angle range: 10-80°), and the results are shown in FIG. 12 . It can be seen from Figure 12 that the diffraction peaks of the composite fiber membrane are different from those of the pure polylactic acid fiber membrane. The composite fiber membrane has two relatively obvious characteristic diffraction peaks around 38.69° and 44.82°, which belong to nano-silver The diffraction peaks of the particles correspond to the diffraction of (111) and (200) crystal planes of elemental silver in the face-centered cubic system (JCPDS card no.04-0783), indicating that the prepared nano-silver structure is a face-centered cubic crystal, which further proves that The presence of silver particles in the composite fiber membrane was confirmed. With the increase of the composite antibacterial agent in the fiber membrane, the intensity of the diffraction peak of the fiber membrane increased, that is, the crystallization performance of the fiber membrane increased, which may be due to the gradual increase in the proportion of the antibacterial agent in the composite fiber membrane. .

Antibacterial performance test: the present invention uses Gram-negative Escherichia coli as the experimental strain, and the antibacterial performance of the fiber membrane is tested by the colony counting method;

Bacterial cultivation: (1) Preparation of liquid medium: Weigh 5g of beef extract on an electronic balance, then put it into a large beaker with a capacity of 1000mL, put 10g of peptone and 5g of sodium chloride powder in turn, and then add 1000mL to remove Stir the ionic water evenly to dissolve it, then adjust the pH value to 7.5 with sodium hydroxide solution, pour 250mL of the above-prepared solution into the Erlenmeyer flask, seal it with a cotton plug, turn on the air volume controller of the ultra-clean workbench, and use Wipe the outer wall of the Erlenmeyer flask with an alcohol cotton ball, then place the Erlenmeyer flask on the ultra-clean workbench, and reserve the remaining liquid for later use; (2) The configuration of the bacterial solution used in the experiment: take a spoonful of the bacterial slope, and inoculate it on an alcohol lamp Spoon for 10 seconds, wait for cooling in the inclined test tube, gently scrape out a circle of bacteria with the inoculation spoon and inoculate it into the liquid medium, carefully seal the seal with self-made absorbent cotton plugs, put the liquid medium with bacteria in the air bath for constant temperature oscillation In the container, set the constant temperature at 37°C, the rotation speed at 130r/min, and cultivate for 24 hours. After the culture solution becomes turbid, it will be the first-generation original bacterial solution. Then take 1ml of the first-generation original bacterial solution and add it to 100ml of the liquid culture solution to continue to grow. Shake at 37°C for 12 hours in a shaker at 130r/min to obtain the second-generation original bacterial solution. Take 1ml of the second-generation original bacterial solution and dilute it 100 times with liquid medium, and then further dilute it 100 times with sterile PBS buffer solution to obtain Bacteria solution for experiment; (3) Preparation of sample (experimental group): Weigh 0.12g of nanofiber membrane, put the sample on ultra-clean workbench and irradiate it with ultraviolet light for 2h to complete sterilization, then add 700ml of sterile PBS buffer solution in turn and 5ml of experimental bacterial solution, put the prepared sample into an air bath constant temperature oscillator, set the constant temperature to 25°C, and the rotation speed to 150r/min, and cultivate for 24h; (4) Preparation of solid medium: the remaining Add 7.5g of agar to the liquid medium, heat it in a water bath to 100°C, stir it evenly, put it into the conical flask, wipe and disinfect the hands of the experimenter with alcohol cotton balls, the outside of the conical flask and the ultra-clean work surface, and wait for the conical flask Cool the liquid medium inside to about 55°C, light the alcohol lamp by touching the wall of the bottle with your hand, and burn the mouth of the conical flask on the flame of the alcohol lamp for 10 seconds, hold the conical flask with your right hand, and open the culture dish with your left hand The lid, the lid is only opened a small slit, quickly pour 25ml of liquid medium into the petri dish, shake gently on the ultra-clean workbench until there are no air bubbles, wait for cooling and then turn it upside down for later use, turn on the ultra-clean workbench The bacteria switch was used to sterilize the culture medium under ultraviolet light for 1 h.

Colony counting: Dilute the cultivated bacterial solution of the experimental group 10 times with sterile water, dilute 3 gradients, make two plates for each gradient, and use the two plates as mutual controls, and make 6 plates for each group of samples. Coat 100 μL of diluted bacterial solution of each gradient in the solid medium, immediately put the coated plate into the incubator, set the temperature at 37°C, observe the growth of the colony after 24 hours of cultivation, and take pictures to record the number of colonies. The average of two control plates allows for a reduction in experimental error. Calculate the antibacterial rate of the fiber membrane according to the formula:

I%=(Nc-Ns)/Nc×100%,

In the formula, Nc and Ns are the number of colonies on the surface of the culture medium after contacting pure polylactic acid and polylactic acid fiber membrane after adding antibacterial agents, respectively.

The test results are shown in Figure 13. In Fig. 13, a is a blank control group; b adds the pure polylactic acid fiber membrane prepared in Comparative Example 1; c adds the fiber membrane prepared in Example 2; d adds the fiber membrane prepared in Example 3; e adds the fiber prepared in Example 4 Membrane; f adds the fiber membrane that embodiment 5 prepares. As can be seen from Figure 13, taking the flat plate of the pure polylactic acid fiber membrane prepared in Comparative Example 1 as a comparison, the relative bacteriostatic rate was calculated, and the pure polylactic acid fiber membrane had a large specific surface area, high porosity, and strong adsorption. Bacteria have adsorptive properties, so compared with the blank group, the number of bacteria on the plate is less; with the increase of the antibacterial agent content, the antibacterial property is gradually enhanced, and the bacteriostatic rate of the fiber membrane prepared in Example 4 has reached 100%.

Mechanical performance test: take three samples for each sample as a group, and the shape of the sample is a long strip with a length*width of 40*2 (mm). The tensile breaking strength of the sample is measured by an electronic single fiber strength machine. Clamp the lower end of the sample so that the tested sample is in a vertical state, then place the sample between the two chucks of the electronic single fiber strength machine, fix it with a holder and keep it still, with a distance of about 10mm. During the whole test process, ensure that the load is uniform, and record the breaking force F(N) on the display screen after the sample breaks, take the average value of the three samples to reduce the error, and the results are shown in Figure 14. It can be seen from Figure 14 that the fracture strength of the prepared nanofiber membranes is relatively small, but the fracture strength of the nanofiber membranes will first decrease and then increase after adding the antibacterial agent. This is because 0.5% and 1% Ag@ Fewer TP particles can only be equivalent to impurities embedded in nanofibers, resulting in insufficient fiber length of PLA nanofibers, which are very easy to break. With the increase of antibacterial agent, the elongation at break of breaking strength gradually becomes larger. When the antibacterial agent content is 1.5%, it exceeds the pure polylactic acid nanofiber membrane, indicating that with the increase of antibacterial agent content, the composite nanofiber film will be improved. The mechanical properties of the fiber membrane, this is because with the addition of nanoparticles, when the nanofiber membrane is subjected to an external force, the Ag@TP particles play a role in transferring and transmitting energy, so that the external force acting on the nanofiber membrane is consumed .

Contact angle test: measure the static water contact angle of the sample to indicate the hydrophilicity of the film, and the test liquid is distilled water. Take two samples for each sample as a group. The shape of the sample is a square of length*width 2*2 (cm). Freeze the image within 10s, you can see that there is a clear small droplet on the image, measure the size of the contact angle by the angle measurement method, the contact angle on the right can be taken as the supplementary angle, and the average value of the two samples is used to reduce error, the results are shown in Figure 15, where (a) is the contact angle of the pure polylactic acid fiber membrane prepared in Comparative Example 1, and (b) is the contact angle of the fiber membrane prepared in Example 4. It can be seen from Figure 15 that the pure polylactic acid nanofiber membrane is a hydrophobic membrane, and the addition of antibacterial agents will improve the hydrophobicity of the polylactic acid nanofiber membrane.

Table 1 lists the contact angle data of the fiber membranes prepared in Examples 1-5 and Comparative Example 1.

The contact angle of the fibrous film prepared in table 1 embodiment 1～5 and comparative example 1

Test the XRD pattern of the composite antibacterial agent prepared in Example 1, and the results are shown in Figure 16. It can be seen from Figure 16 that this figure conforms to the data on 04-0783 on the JCPDS card (2θ is 38.096°, 44.257°, 64.406° and 77.452°), which correspond to (111) and (200) of cubic silver respectively , (220) and (311) crystal planes, indicating that the generated material is face-centered cubic pure-phase elemental silver, with relatively pure particles and almost few impurity ions.

Test the ultraviolet-visible absorption spectrum of the composite antibacterial agent prepared in Example 1, and the results are shown in Figure 17. It can be seen from Figure 17 that the absorption peak is around 380-420nm, which is in line with the absorption peak of nano-silver particles.

Test the antibacterial performance of the composite antibacterial agent prepared in Example 1, and the results are shown in Figure 18. In the figure (a) no compound antibacterial agent is added, and (b) to (d) add the same content of compound antibacterial agent. Calculate the antibacterial rate of compound antibacterial agent:

In summary, the composite fiber membrane prepared by the present invention has excellent antibacterial performance and mechanical strength.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (8)

1. a preparation method of polylactic acid antibacterial composite fiber film, comprising the following steps: (1) Silver source is mixed with tea polyphenols and water, and reduction reaction is carried out to obtain composite antibacterial agent; (2) the composite antibacterial agent that described step (1) is obtained is mixed with polylactic acid, solvent and coupling agent, obtains cortex spinning solution; (3) mixing polylactic acid with a solvent to obtain a core spinning solution; (4) coaxial electrospinning is carried out by the cortex spinning liquid that described step (2) obtains and the core layer spinning liquid that described step (3) obtains, obtains polylactic acid antibacterial composite fiber film; The steps (1) and (3) have no sequence; The ratio of the amount of tea polyphenols to the silver source in the step (1) is (1-1.5): 1; In the step (2), the mass ratio of the composite antibacterial agent to the polylactic acid is (0.5-3):5. 2. preparation method according to claim 1, is characterized in that, the solvent in described step (2) and step (3) comprises N, N-dimethylformamide and dichloromethane. 3. The preparation method according to claim 2, characterized in that the mass ratio of the dichloromethane to N,N-dimethylformamide is (2-3):1. 4. The preparation method according to claim 1, characterized in that the mass concentration of polylactic acid in the skin layer spinning solution in the step (2) is 4-6%. 5. preparation method according to claim 1, is characterized in that, the coupling agent in described step (2) comprises silane coupling agent; The mass ratio of described coupling agent and composite antibacterial agent is (0.05～0.2 ):1. 6. The preparation method according to claim 1, characterized in that, the spinning voltage of coaxial electrospinning in the step (4) is 14 to 16 kV; the spinning distance of coaxial electrospinning is 8 to 14 cm ; During coaxial electrospinning, the propulsion speeds of the cortex spinning solution and the core spinning solution are independently 1-2 mL/h. 7. The polylactic acid antibacterial composite fiber membrane prepared by the preparation method described in any one of claims 1 to 6. 8. the application of the polylactic acid antibacterial composite fiber membrane described in claim 7 in the field of antibacterial.

Images