A left-handed polylactic acid coated beta-glycine composite fiber film, a preparation method and application thereof

Abstract

The application relates to a kind of left-handed poly (lactic acid) coated beta-glycine composite fiber film and preparation method and application, belong to piezoelectric nanogenerator field, steps are as follows: glycine is made into spinning solution with poly (lactic acid), and coaxial electrospinning is carried out as core layer and shell layer solution respectively, under the action of electric field and shell poly (lactic acid) solution, the poly (lactic acid) fiber film wrapped beta-glycine is prepared, the glycine is amino acid small molecule contained in human body, and the poly (lactic acid) is biodegradable and implantable biomaterial, the beta-glycine crystal of the application and PLLA composite fiber film have high piezoelectric performance, implant safety and full degradability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of β-glycine composite fiber film and method, and relates to a left-handed polylactic acid coated β-glycine composite fiber film and a preparation method and application thereof; in particular, to a left-handed polylactic acid coated β-glycine crystal coaxial fiber film with high piezoelectricity and full degradability and a preparation method thereof. BACKGROUND

[0002] Piezoelectric materials have the ability to convert mechanical energy into electrical energy, and thus become the core material of many medical devices. Generally, these materials will be used for implantation in the human body for physiological feature monitoring, human energy collection and self-power supply, drug release and promotion of healing of damaged tissues. Organic biomaterials have become the first choice for implant materials due to their excellent biocompatibility and degradation capacity, and polylactic acid is the most mature, most medically applied and artificially synthesized biodegradable polymer material, and is a medical safety material approved by the US Food and Drug Administration (FDA). However, the piezoelectric performance of polylactic acid is low, and the use of high piezoelectric ceramic as a nano-filling material has problems such as complicated preparation process, potential harmful substances to the human body, and incomplete degradation. Therefore, it is very necessary to find a kind of biomaterial with excellent piezoelectric performance and degradation performance.

[0003] Among the current biologic piezoelectric materials, β-glycine has extremely high piezoelectric performance. Glycine is the simplest non-chiral amino acid, and has three different crystal morphologies of α, β and γ. Among them, α-glycine is a stable crystal form, but has no piezoelectric performance. The stability of γ-glycine is better than that of β-glycine, but its piezoelectric performance is weak. Literature 1“G. Sarah et al, Control of piezoelectricity in amino acids by supramolecular packing[J]. Nature Materials, 2018, 17: 180-186” theoretically calculates the piezoelectric performance of various crystal forms of glycine, and obtains that the highest predicted piezoelectric voltage constant of β-glycine crystal is 8VmN -1 , which is one order of magnitude larger than the currently used polymers and even piezoelectric ceramics. In actual tests, the shear piezoelectric performance of β-glycine is as high as 178pm V -1 , which is close to that of piezoelectric ceramics barium titanate or lead zirconate titanate. However, although β-glycine has extremely high piezoelectric performance, due to its physical properties such as instability of crystal form and easy solubility in water, its preparation and application are difficult.

[0004] In the preparation of β-glycine, literature 2 "E. Seyedhosseini, et al. Growth and nonlinear optical properties of β-glycine crystals grown on Pt substrates. Cryst. Growth Des, 2014, 14: 2831-2837" obtained relatively stable β-glycine microcrystals by water solution evaporation driven glycine crystallization process on Pt(111) / SiO2 / Si substrates with high crystallinity and chemical activity. Literature 3 "Zhang Z. et al, Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling [J]. Nature Communications, 2023 14: 4094" proposed a nano-confinement method to prepare β-glycine crystals, and the crystal grains were oriented and arranged under in-situ electric field, obtaining stable nano-β-glycine composed film, with piezoelectric strain coefficient of 11.2 pmV -1 , piezoelectric voltage coefficient of 252 x 10 -3 VmN -1 . At present, there are few studies on biodegradable and high piezoelectricity biomaterials. The existing methods for preparing stable β-glycine that can be used for subsequent processing and utilization mainly include Pt(111) crystal face induction and ion confinement method under large electric field. The cost required by the induction method is high; and the large electric field spraying requires high equipment, and the glycine prepared by the two methods cannot be directly applied in the field of implantable nanogenerator.

[0005] The current mainstream methods for using high piezoelectric performance β-glycine in implantable piezoelectric nanogenerators mainly include self-assembly and subsequent processing of β-glycine crystals. As described in document 4 “F. Yang et al, Wafer-scale hetero-structured piezoelectric bio-organic thin films [J]. Science, 2021, 373: 337-342”, a sandwich structure thin film is obtained by self-assembly of molecules in a mixed solution of poly PVA and glycine through hydrogen bonding during solvent evaporation, and the middle layer is γ-glycine with piezoelectric performance. At present, the self-assembly of different high molecular materials and glycine basically obtains γ-glycine with small piezoelectric performance. To realize the application of β-glycine, the preparation method in document 2 or 3 is used to obtain β-glycine crystals first, and then the subsequent process is used to combine them with biodegradable implantable biomaterials. For example, document 5 “M. T. Chorsi et al, Highly piezoelectric, biodegradable, and flexible amino acid nanofibers for medical applications [J]. Science. Advances, 2023, 9: 6075” is to prepare β-glycine crystals by the preparation method in document 2, and then grind them into nano-level particles and combine them with polycaprolactone (PCL) to prepare PCL and β-glycine composite nanofiber film for in vivo implantation. This method can obtain a high piezoelectric composite film, but the preparation of β-glycine and the subsequent processing require high equipment and high cost.

[0006] In summary, there is currently little research on biodegradable and high piezoelectricity biomaterials. The existing preparation methods and implantation applications of β-glycine require high preparation conditions and high cost. There is currently no simple and low-cost method to prepare directly applicable β-glycine. The present application combines the preparation principles in the above documents, selects left-handed polylactic acid (PLLA) with piezoelectric performance, high safety and degradability as the shell material in the coaxial electrospinning process, and uses its limited effect on glycine solution in the electric field traction to prepare composite fibers wrapped with β-glycine. Through one-step method, the preparation of β-glycine is realized, and the chemical stability of β-glycine is maintained by coating PLLA. SUMMARY

[0007] TECHNICAL PROBLEMS TO BE SOLVED

[0008] In order to avoid the shortcomings of the prior art, the application provides a left-handed polylactic acid coated beta-glycine composite fiber film, a preparation method and application, and realizes preparation of a high piezoelectricity, implantable and fully degradable piezoelectric film.

[0009] Technical scheme

[0010] A method for preparing a left-handed polylactic acid coated beta-glycine composite fiber film, characterized in that: PLLA electrospinning solution is used as a shell layer solution, and glycine solution is used as a core layer solution, and coaxial electrospinning is adopted; during the coaxial electrospinning, a needle is connected to a positive electrode, an aluminum foil is used to cover a receiving cylinder, and a negative electrode is connected; after the electrospinning is completed, the aluminum foil covered with the film is removed, and the film is peeled off from the aluminum foil after drying under vacuum conditions to obtain a PLLA composite fiber film with a core-shell structure, which is wrapped with beta-glycine and PLLA / beta-glycine; during the electrospinning process, the temperature is not more than 10 DEG C, and the humidity is in the range of 25-40%.

[0011] The positive voltage of the needle is in the range of 14-18 kV, and the negative voltage is in the range of -1 to -2 kV.

[0012] The distance between the needle tip and the receiving cylinder is 10-15 cm.

[0013] The drying under vacuum conditions is drying for 12 h under the conditions of vacuum and ≤35 DEG C.

[0014] During the coaxial electrospinning, the sum of the feeding rates of the shell layer solution and the core layer solution is not more than 0.3 mm / min; and the feeding rate ratio of the PLLA solution to the glycine solution is 20:1-2:1.

[0015] The coaxial electrospinning needle has the following parameters: the coaxial electrospinning needle has a shell layer with a diameter of 0.8-1.2 mm and a core layer with a diameter of 0.2-0.5 mm.

[0016] The preparation of the core layer solution: glycine is dissolved in distilled water DW to prepare a 5-10 wt% glycine solution; N,N-dimethylformamide DMF solution is added to the glycine solution, and the volume ratio of distilled water to DMF is in the range of V DW :V DMF = 12:1-6:1.

[0017] The preparation of the shell layer solution: a 6-13 wt% ester-terminated left-handed polylactic acid (OH-PLLA-COOR, namely PLLA) solution is prepared, and dichloromethane DCM is used as a solvent; the solution is stirred and ultrasonicated until the solution is clear; then DMF is added to the PLLA dichloromethane solution, and the volume ratio of dichloromethane to DMF is in the range of V DCM :V DMF = 4:1-6:1.

[0018] The left-handed poly-lactic acid coated beta-glycine composite fiber film prepared by the preparation method, wherein the PLLA is used as the outer layer wrapping material to isolate the inner layer beta-glycine from the outside, so that the beta-glycine is stably present; the piezoelectric output of the PLLA composite fiber film wrapping the beta-glycine is 12V / 940nA; the force applied to the film is 10N, 2Hz.

[0019] The application of the left-handed poly-lactic acid coated beta-glycine composite fiber film prepared by the preparation method, wherein the wrapping of the PLLA ensures the preparation and stable existence of the beta-glycine, and is used as the bio-piezoelectric material for in-vivo implantation.

[0020] Beneficial effects

[0021] The left-handed poly-lactic acid coated beta-glycine composite fiber film and the preparation method and application thereof provided by the application belong to the field of piezoelectric nanogenerators, and the steps are as follows: glycine and polylactic acid are made into a spinning solution, and are used as the core layer and the shell layer solution respectively for coaxial electrospinning, under the action of the electric field and the shell polylactic acid solution, the polylactic acid fiber film wrapping the beta-glycine is prepared, the glycine is a small molecule amino acid contained in the human body, the polylactic acid is a biodegradable and implantable biomaterial, the beta-glycine crystal and the PLLA composite fiber film have high piezoelectric performance, implantation safety and full degradability.

[0022] The application provides a one-step method for preparing a beta-glycine and PLLA composite fiber film.

[0023] Firstly, the composite fiber film of the PLLA and the beta-glycine has not been used in the field of piezoelectric nanogenerators, the beta-glycine has high shear piezoelectric performance due to the particularity of the crystal structure, and is a bio-piezoelectric material with great application value, the PLLA has flexibility, biocompatibility and hydrophobicity, and is an excellent shell material.

[0024] Secondly, compared with other biomaterials, the glycine exists in the human body and is easily soluble in water, the PLLA is approved by the US Food and Drug Administration to be used for in-vivo implantation, and therefore the safety and biocompatibility of the combination of the two materials are extremely high, and the prepared composite film has great medical value.

[0025] Third, in the structural design, the application ingeniously utilizes the limited action of PLLA on glycine solution, in the coaxial electrospinning, the needle head will gather the liquid drops of core-shell structure, the liquid drops form fibers under the traction of electric field, due to the excellent electrospinning characteristics of PLLA, it will form nanoscale hollow fibers, and limit the glycine solution in the pore size of the hollow fiber, due to the glycine solution is limited in nanoscale, it will preferentially form unstable beta-glycine crystal form in the crystallization process, so that the PLLA composite fiber wrapped with beta-glycine is collected on the receiving drum; compared with document 3, the application can obtain beta-glycine without large electric field strength, and the prepared beta-glycine can be directly applied without subsequent processing, simplifying the preparation process;

[0026] In order to prove the limited action of PLLA on glycine, in example 2, the core-shell material is reversed, that is, the PLLA solution is used as the core solution, and the glycine solution is used as the shell solution, and the feeding speed ratio of the shell solution to the core solution is unchanged, it can be found that the limited action of PLLA is lost, and the glycine crystal obtained by ionization under the action of the electric field is alpha-glycine crystal, which has been proved to have no piezoelectric property;

[0027] Finally, the prepared composite fiber film shows high piezoelectric property, as shown in the accompanying Figure 6 Fig. 2, the piezoelectric output of pure PLLA fiber film is 5V / 400nA, and the piezoelectric output of the prepared PLLA composite fiber film wrapped with beta-glycine is 12V / 940nA; the force applied to the film is 10N, 2Hz.

[0028] The application innovatively utilizes the electric field and the wrapping action of the outer PLLA, and prepares the PLLA wrapped beta-glycine composite film through one-step simple electrospinning, which realizes the simple preparation of beta-glycine, ensures the stable existence of beta by the wrapping of PLLA, and at the same time, the prepared composite film only needs to be processed by one step of spinning, so that the operation is simple, the cost is low, and the high piezoelectric property, biocompatibility and full degradation property of the composite piezoelectric nanofilm are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is the preparation method flow chart of the method embodiment 1 of the application.

[0030] Figure 2 is the optical image of the PLLA / beta-glycine composite film prepared by the method embodiment 1 of the application.

[0031] Figure 3 is the XRD graph of the PLLA / beta-glycine composite film prepared by the method embodiment 1 of the application, wherein a graph is the PDF standard card of beta-glycine, and b is the XRD curve of the composite film.

[0032] Figure 4 SEM image of PLLA / β-glycine composite film prepared by the method of the present application, embodiment 1.

[0033] Figure 5 TEM image of PLLA / β-glycine composite film prepared by the method of the present application, embodiment 1.

[0034] Figure 6 Output performance chart of pure PLLA fiber film and PLLA / β-glycine composite film prepared by the method of the present application, embodiment 1.

[0035] Figure 7 XRD chart of glycine / PLLA composite film prepared by the method of the present application, embodiment 2, wherein a chart is a PDF standard card of α-glycine, and b is XRD curve of α-glycine / PLLA composite film. DETAILED DESCRIPTION

[0036] The present application will be further described in conjunction with embodiments and drawings:

[0037] The present application provides a one-step method for preparing β-glycine and PLLA composite fiber film. The method selects 6-13 wt% of PLLA electrospinning solution as the shell layer, 5-10 wt% of glycine solution as the core layer, and carries out coaxial electrospinning according to the ratio of PLLA solution to glycine solution feeding speed ratio of 20:1-2:1. In the spinning process, the two processes of ionization and traction of the solution by the electric field and the confinement process of the glycine solution by the shell material PLLA are synergistically prepared to prepare the PLLA nanofiber film wrapped with β-glycine crystal grains. In the composite film, the β-glycine crystal grains have high piezoelectric performance, so the overall piezoelectric output of the composite film can be improved; PLLA as the outer wrapping material can isolate β-glycine from the outside, so that β-glycine can exist stably. The present application is simple to operate and has low preparation cost. The use of PLLA coating ensures the preparation and stable existence of β-glycine, which can be directly used for in vivo implantation.

[0038] The technical solution adopted by the present application to solve the technical problems is: a method for preparing β-glycine crystal and PLLA composite fiber film, characterized by comprising the following steps:

[0039] Step one, preparation of core solution: dissolve glycine in distilled water (DW) to prepare 5-10 wt% glycine solution; add a certain amount of N,N-dimethylformamide (DMF) solution to the glycine solution, and the volume ratio of distilled water to DMF is in the range of V DW :V DMF =12:1-6:1.

[0040] Step two, preparation of the shell solution: prepare a 6-13wt% ester-terminated poly-L-lactic acid (OH-PLLA-COOR, hereinafter abbreviated as PLLA) solution in dichloromethane (DCM) solvent. Stir and ultrasonic the solution until the solution is clear; then add a certain amount of DMF to the PLLA dichloromethane solution, the volume ratio of dichloromethane to DMF is in the range of V DCM :V DMF = 4:1 ~ 6:1. The whole process is carried out below 10℃, and the volatilization of DCM is reduced as much as possible.

[0041] Step three, use the electrospinning injector syringe to suck the prepared PLLA solution and glycine solution according to the feeding speed ratio, install it on the electrospinning machine to perform coaxial electrospinning, and then the PLLA / β-glycine composite fiber film with core-shell structure wrapped with β-glycine is obtained.

[0042] Electrospinning parameters: select a coaxial electrospinning needle with a shell diameter of 0.8-1.2mm and a core diameter of 0.2-0.5mm. The needle is connected to the positive electrode, and the voltage is in the range of 14-18kV; the receiving drum is wrapped with aluminum foil and connected to the negative electrode, and the voltage is -1- -2kV. The distance between the needle tip and the receiving drum is 10-15cm. The push speed ratio of the shell solution and the core solution is 20:1-2:1, and the sum of the feeding ratio of the shell solution and the core solution is ensured to be not more than 0.2mm / min.

[0043] Spinning environment parameters: the temperature during the spinning process is not more than 10℃, and the humidity is in the range of 25-40%.

[0044] Step four, after the spinning is completed, remove the aluminum foil covered with the film, and dry it in a vacuum and at a temperature of ≤35℃ for 12h. After drying is completed, the PLLA / β-glycine film can be removed.

[0045] The examples described below are only a part of the embodiments of the present application, rather than all the embodiments. Based on the examples in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application. In addition, the protection scope of the present application should not be limited to the specific experimental methods or specific parameters described below.

[0046] The following examples refer to Figures 1-7 .

[0047] Example 1:

[0048] (1) Preparation of the core solution: dissolve 1g of glycine powder in 6mL of distilled water, after the glycine is completely dissolved, take 3ml of glycine solution, add 0.25mL of DMF, and stir to mix the solution uniformly.

[0049] (2) Preparation of the shell solution: 1.2 g of PLLA was weighed and dissolved in 7 mL of dichloromethane by stirring and ultrasonic alternately for 3 h. After the PLLA was fully dissolved and the solution was clear and transparent, 3 mL of DMF was added to the mixed solution, and stirred for 60 min to mix uniformly, and then left to eliminate bubbles in the solution. The whole process was ensured to be carried out below 10 °C.

[0050] (3) 4 mL of the PLLA solution and 1.3 mL of the glycine solution were respectively taken by two electrospinning syringe needles, and the needles were connected with coaxial electrospinning needles. The PLLA solution was used as the shell spinning solution, and the glycine solution was used as the core spinning solution, and coaxial electrospinning was carried out to obtain a PLLA / β-glycine film with a core-shell structure on the receiving drum. The specific parameters of electrospinning were as follows:

[0051] The coaxial electrospinning needle with a shell diameter of 1.1 mm and a core diameter of 0.4 mm was selected. The needle was connected to the positive electrode, and the voltage was 17 kV; the receiving drum was wrapped with aluminum foil and connected to the negative electrode, and the voltage was -2 kV. The distance between the needle tip and the receiving drum was 12 cm, and the rotating speed of the receiving drum was 140 r / min. The pushing speed of the needle cylinder containing the shell solution was 0.15 mm / min, and the pushing speed of the needle cylinder containing the core solution was 0.05 mm / min.

[0052] (4) After the spinning was completed, the aluminum foil on which the fiber film was received was removed, and dried in a vacuum at 30 °C for 12 h. After drying, the PLLA / β-glycine film was obtained.

[0053] Figure 1 is a flow chart of the preparation method. As can be seen from Figure 2 , the PLLA / β-glycine composite film prepared by coaxial electrospinning has good surface uniformity and flatness, and the film has flexibility. As can be seen from Figure 3 , the glycine in the composite film prepared by coaxial electrospinning is β-glycine, which is consistent with the peak position of the standard card. As can be seen from Figure 4 , the composite fiber obtained by coaxial electrospinning is defect-free and has a smooth surface, and the fiber has a hollow structure in the middle, which proves the existence of the core-shell structure. As can be seen from Figure 5 , the fiber inside the composite film contains β-glycine grains. As can be seen from Figure 6 , the piezoelectric output of the pure PLLA fiber film is 5 V / 400 nA, and the piezoelectric output of the PLLA composite fiber film prepared by wrapping β-glycine is 12 V / 940 nA.

[0054] Example 2:

[0055] (1) Preparation of the core solution: 1.2 g of PLLA was dissolved in 7 mL of dichloromethane by stirring and ultrasonic alternately for 3 h. After the PLLA was fully dissolved and the solution was clear and transparent, 3 mL of DMF was added to the mixed solution, and stirred for 60 min to mix uniformly, and then left to eliminate bubbles in the solution. The whole process was ensured to be carried out below 10°C.

[0056] (2) Preparation of the shell solution: 1 g of glycine powder was dissolved in 6 mL of distilled water. After the glycine was completely dissolved, 3 mL of the glycine solution was taken, 0.25 mL of DMF was added, and the solution was stirred to mix uniformly.

[0057] (3) 4 mL of the PLLA solution and 1.3 mL of the glycine solution were taken by two electrospinning syringe needles respectively, the needles were connected with coaxial electrospinning needles, the PLLA solution was used as the core layer spinning solution, the glycine solution was used as the shell layer spinning solution, coaxial electrospinning was carried out, and a glycine / PLLA composite film could be obtained on the receiving drum. The specific parameters of electrospinning were as follows:

[0058] The coaxial electrospinning needle with a shell layer diameter of 1.1 mm and a core layer diameter of 0.4 mm was selected. The needle was connected to the positive electrode, the voltage was 17 kV; the receiving drum was wrapped with aluminum foil and connected to the negative electrode, the voltage was -2 kV. The distance between the needle tip and the receiving drum was 12 cm, and the rotating speed of the receiving drum was 140 r / min. The pushing speed of the needle cylinder containing the shell layer solution was 0.05 mm / min, and the pushing speed of the needle cylinder containing the core layer solution was 0.15 mm / min.

[0059] (4) After the spinning was completed, the aluminum foil on which the fiber film was received was taken out and dried in a vacuum at 30°C for 12 h. After drying, the glycine / PLLA composite film was obtained.

[0060] The preparation process of Example 2 was the same as that of Example 1, the only difference was that the core layer solution and the core layer solution were exchanged in position to prove the key role of the confinement of PLLA in the formation of high-voltage electric β-glycine in the coaxial electrospinning process. It can be seen from Figure 7 that the glycine crystal obtained in the composite film is α-glycine without piezoelectric property when the PLLA is used as the core layer solution and the glycine is used as the shell layer solution for spinning, and the glycine solution is no longer confined by the outer layer of PLLA.

Claims

1. A method for preparing a β-glycine composite fiber film coated with a left-handed polylactic acid, characterized by: The PLLA electrospinning solution is used as the shell layer solution, and the beta-glycine solution is used as the core layer solution, and a coaxial electrospinning is adopted; during the coaxial electrospinning, the needle is connected to the positive electrode, the receiving roller is covered with an aluminum foil, and the negative electrode is connected; after the electrospinning is completed, the aluminum foil covered with the film is removed, and after drying under vacuum, the film is removed from the aluminum foil to obtain the PLLA / β-glycine composite fiber film with a core-shell structure wrapping the beta-glycine; during the electrospinning, the temperature is not more than 10 ℃, and the humidity is in the range of 25-40%. Preparation of the core layer solution: Dissolve β-glycine in distilled water DW to prepare a 5-10 wt% β-glycine solution; add N,N-dimethylformamide DMF solution to the β-glycine solution, the volume ratio of distilled water to DMF is in the range of V DW :V DMF = 12:1-6:1; Preparation of the shell solution: PLLA solution with a concentration of 6-13 wt% ester-terminated L-polylactic acid in dichloromethane (DCM) was prepared; the solution was stirred and ultrasonicated until the solution was clear; then DMF was added to the PLLA solution in DCM, and the volume ratio of DCM to DMF was in the range of V DCM :V DMF = 4: 1 ~ 6:

1.

2. The method for preparing a β-glycine composite fiber film coated with a levorotatory polylactic acid according to claim 1, characterized by: The positive voltage of the needle is in the range of 14-18 kV, and the negative voltage is in the range of -1 to -2 kV.

3. The method of claim 1, wherein the preparation of the β-glycine composite fiber film coated with the L-polylactic acid is characterized by: The distance between the needle and the receiving roller is in the range of 10-15 cm.

4. The method of claim 1, wherein the preparation of the β-glycine composite fiber film coated with the L-polylactic acid is characterized by: The drying under vacuum is drying under vacuum and at a temperature of ≤35 ℃ for 12 h.

5. The method of claim 1, wherein the preparation of the β-glycine composite fiber film coated with the L-polylactic acid is characterized by: During the coaxial electrospinning, the sum of the feeding rates of the shell layer solution and the core layer solution is not more than 0.3 mm / min; the feeding rate ratio of the PLLA solution to the glycine solution is in the range of 20:1 to 2:

1.

6. The method of claim 1, wherein the preparation of the β-glycine composite fiber film coated with the L-polylactic acid is characterized by: The coaxial electrospinning needle parameters are as follows: the coaxial electrospinning needle with a shell layer diameter of 0.8-1.2 mm and a core layer diameter of 0.2-0.5 mm.

7. The composite film of β-glycine coated with the L-polylactic acid according to the preparation method of any one of claims 1 to 6, characterized in that: The PLLA is used as the outer wrapping material to isolate the inner beta-glycine from the outside environment, so that the beta-glycine can stably exist; the piezoelectric output of the PLLA composite fiber film wrapping the beta-glycine is 12 V / 940 nA; the force applied to the film is 10 N, and the frequency is 2 Hz.

8. The use of the β-glycine composite fiber film coated with the levorotatory polylactic acid prepared by the method according to any one of claims 1 to 6, characterized in that: The coating of PLLA ensures the preparation and stable existence of beta-glycine, and is used as a bio-piezoelectric material for in-vivo implantation.

Images