Multiscale reinforced dipole shell-core microspheres, preparation method and composite bio-piezoelectric

Abstract

The application discloses a kind of multi-scale reinforced dipole shell-core microspheres, preparation method and its composite biological electret, it is related to biomedical, bionic technical field, medical dielectric material and so on field, the preparation method includes: by emulsion phase separation and complex coacervation method preparation shell-core structure microsphere;Preparation polydimethylsiloxane dipole chamber;Take the shell-core structure microsphere is placed in the polydimethylsiloxane dipole chamber and cover seal, solidification treatment is carried out polarization treatment, again from the polydimethylsiloxane dipole chamber, obtain multi-scale reinforced dipole shell-core microspheres.The technical scheme of the present application is simple, the production cost is low, dipole charge density is high, charge stability is good, biocompatibility is good, and processability is strong, the multi-scale shell-core structure electret microsphere prepared and its composite biological electret have good dipole charge stability, and surface charge change can be regulated by exogenous stimulation (such as stress change, ultrasonic stimulation).

Description

Technical Field

[0001] This invention relates to the fields of biomedicine, biomimetic technology, and medical dielectric materials, specifically to a multi-scale reinforced dipole core microsphere, its preparation method, and its composite bioelectrode. Background Technology

[0002] The biological effects (piezoelectric, pyroelectric, and ferroelectric effects, etc.) produced by bio-electrets have been widely applied in tissue repair, biosensing, and intelligent biomedical devices. Electrets, as exogenous electrical stimulation, primarily utilize the piezoelectric effect, electrostatic effect, and the generated local microcurrent. The electrostatic field of an electret mainly originates from the electric field generated by space charges outside the material and the electric field generated by dipole charges inside the material. The piezoelectric effect of an electret mainly occurs when it is subjected to tensile or compressive stress, causing strain that induces changes in charge density at both ends of the material, thereby altering the electric field. Since the 1950s, many studies have introduced bio-electrets as an exogenous electrical stimulus. By spontaneously generating micro-electric fields and microcurrents to compensate for or modulate the electret state of the human microenvironment, it can improve blood microcirculation, prevent thrombosis, improve vascular permeability, promote bone growth and fracture healing, promote transdermal drug absorption, and facilitate controlled in vitro drug release.

[0003] Currently, inert bio-electrode materials are widely used, mainly including inorganic semiconductors, ceramics, and inert polymers, such as silicon-based materials (SiO2), calcium titanate (CaTiO3) ferroelectric ceramics, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polydimethylsiloxane (PDMS) piezoelectric materials. They possess characteristics such as high stability, resistance to high temperatures and humidity, and long lifespan; however, their application carries the risk of immune rejection and exhibits poor mechanical properties. Bio-based electrets, such as chitosan, hyaluronic acid, polylactic acid, hydroxyapatite, and natural cellulose, offer better biocompatibility and have received increasing attention in recent years. However, the low charge density, short lifespan, and rapid discharge of bio-based electrets often fail to meet their application requirements. Summary of the Invention

[0004] To address the above issues, this invention provides a multi-scale reinforced dipole core-shell microsphere, its preparation method, and its composite bio-electroporate. The core material is primarily prepared using an emulsion phase separation method to obtain micro / nano-scale microspheres. Biomolecules are uniformly coated onto the core material using a complex condensation method as the wall material. The prepared core-shell microspheres are then placed in a polydimethylsiloxane (PDMS) dipole chamber for thermal polarization to obtain a multi-scale core-shell structure electret microsphere. The designed and constructed multi-scale core-shell structure electret microspheres can be used as "dipole-like" physical dopants to incorporate different biopolymers. Thermal polarization of the "dipole-like" composite biomaterial within the dipole chamber yields a reinforced dipole composite bio-electroporate. This preparation method is simple, low-cost, produces high dipole charge density, exhibits good charge stability, good biocompatibility, and strong processability. The prepared multi-scale core-shell structure electret microspheres and their composite bio-electroporates possess excellent dipole charge stability, and their surface charge changes can be modulated by external stimuli (such as stress changes or ultrasonic stimulation). This study is of great significance for understanding the mechanisms by which exogenous electret states regulate endogenous electret states in organisms and for developing new tissue engineering treatments. It can also be applied to fields such as biosensing, biomimetic skin, medical dielectric materials, and tissue repair.

[0005] According to a first aspect of the present invention, a method for preparing multi-scale reinforced dipole core-shell microspheres is provided, wherein the preparation method includes:

[0006] Step 1: Prepare shell-core structured microspheres by emulsion phase separation and complex condensation method;

[0007] Step 2: Preparation of polydimethylsiloxane (PDMS) dipole chamber;

[0008] Step 3: Place the shell-core structured microspheres into the polydimethylsiloxane (PDMS) dipole chamber and seal the opening. After curing, perform polarization treatment and then remove them from the polydimethylsiloxane (PDMS) dipole chamber to obtain multi-scale reinforced dipole shell-core microspheres.

[0009] Furthermore, step 1 specifically includes:

[0010] Step 1.1: Under low-speed mechanical stirring, take a certain amount of material with dipolar properties and place it in a container with the gum arabic aqueous solution and place the whole container in a water bath. Heat under stirring until completely melted.

[0011] Step 1.2: Increase the stirring speed and maintain emulsification. Under stirring conditions, rapidly cool down and add chitosan acetate solution, followed by dropwise addition of acetic acid solution to adjust the pH to the isoelectric point of chitosan.

[0012] Step 1.3: Cool down the whole process, then add a certain amount of glutaraldehyde, slowly crosslink and mix thoroughly, then quickly heat up and continue the crosslinking reaction;

[0013] Step 1.4: After vacuum filtration and centrifugal washing, the microspheres with shell-core structure are freeze-dried for a period of time to obtain the microspheres.

[0014] Further, in step 1.1, the weight percentage of the gum arabic aqueous solution is 1wt%-2wt%.

[0015] Further, in step 1.2, the stirring speed is increased to 1000-1200 r / min, and the emulsification time is maintained for 15-30 min; the temperature is rapidly reduced to 50°C under stirring, and 1% (w / v) chitosan acetate solution is slowly added under stirring, followed by slow dropwise addition of 10% acetic acid solution, adjusting the pH to the isoelectric point of chitosan, and reacting for 30 min.

[0016] Further, in step 1.3, the overall temperature is lowered to 0°C, a certain amount of 2% glutaraldehyde is added, the mixture is slowly crosslinked and thoroughly mixed for 30 minutes, the temperature is rapidly raised to 50°C, and the crosslinking reaction continues for 60 minutes.

[0017] Furthermore, in step 1.4, the sample is placed in a freeze dryer at -50°C and 10Pa for freeze drying for 24 hours.

[0018] Furthermore, step 2 specifically includes:

[0019] Step 2.1: Weigh a certain amount of polydimethylsiloxane, add curing agent and stir thoroughly to obtain PDMS silicone prepolymer, and then perform defoaming treatment;

[0020] Step 2.2: Take a portion of the PDMS silicone prepolymer and place it in a polytetrafluoroethylene mold. Let it stand and cure in a constant temperature oven to form a substrate polydimethylsiloxane at the bottom of the polytetrafluoroethylene mold.

[0021] Step 2.3: Place the polypropylene box and a portion of the PDMS silicone prepolymer together in a polytetrafluoroethylene mold with the polydimethylsiloxane substrate, and let it stand in a constant temperature oven to cure, thereby obtaining a polydimethylsiloxane (PDMS) dipole chamber.

[0022] Furthermore, in step 2.3, the inner diameter of the polypropylene box is 7.0 cm and the height is 5 mm.

[0023] Furthermore, in step 2.1, the mass fraction of the curing agent is 1%-5%.

[0024] Furthermore, in steps 2.2 and 2.3, the conditions for static curing are: static curing in a constant temperature oven at 50℃-60℃ for 24 hours.

[0025] Furthermore, step 3 specifically includes:

[0026] Step 3.1: Place the shell-core structured microspheres into the polydimethylsiloxane (PDMS) dipole chamber, seal the opening, and then let it stand and cure in a constant temperature oven;

[0027] Step 3.2: Place the PDMS mold containing the core-shell structured microspheres between two thermally polarized electrodes and put them together in a constant temperature oven;

[0028] Step 3.3: The electrode is connected to the power supply of the thermal polarization charging device for polarization treatment, and then taken out from the polydimethylsiloxane (PDMS) dipole chamber to obtain multi-scale reinforced dipole core microspheres.

[0029] Furthermore, in step 3.3, the temperature of the constant temperature oven is 25 to 100°C, the power supply is set to -20 to -30kV, and the charging time is 10 to 60 minutes.

[0030] According to a second aspect of the present invention, a multi-scale reinforced dipole shell-core microsphere is provided, wherein the multi-scale reinforced dipole shell-core microsphere is prepared by the preparation method described in any of the above aspects.

[0031] According to a third aspect of the present invention, a composite bio-electroporium with shell-core structure electret microspheres for dipole reinforcement is provided. The composite bio-electroporium with shell-core structure electret microspheres for dipole reinforcement is prepared based on multi-scale reinforced dipole shell-core microspheres as described above. The preparation method of the composite bio-electroporium with shell-core structure electret microspheres for dipole reinforcement is as follows:

[0032] Step 1: Take a certain amount of the multi-scale reinforced dipole shell-core microspheres, screen the particle size and then dope them into the bioactive macromolecular matrix. After ultrasonic stirring to disperse them evenly, they are then shaped and processed to obtain composite material microspheres.

[0033] Step 2: Preparation of polydimethylsiloxane (PDMS) dipole chamber;

[0034] Step 3: Place the composite material microspheres into the polydimethylsiloxane (PDMS) dipole chamber and seal the opening. After curing, perform polarization treatment and then remove them from the polydimethylsiloxane (PDMS) dipole chamber to obtain a composite bio-electrode with a core-shell structure electret microsphere-reinforced dipole.

[0035] Furthermore, step 3 specifically includes:

[0036] Step 3.1: Place the composite material microspheres into the polydimethylsiloxane (PDMS) dipole chamber, seal it, and then let it stand and cure in a constant temperature oven;

[0037] Step 3.2: Place the PDMS mold containing the composite material between two thermally polarized electrodes and put them together in a constant temperature oven;

[0038] Step 3.3: The electrode is connected to the power supply of the thermal polarization charging device for polarization treatment, and then taken out from the polydimethylsiloxane (PDMS) dipole chamber to obtain a composite bio-electrode with a core-shell structure electret microsphere reinforced dipole.

[0039] Furthermore, in step 3.3, the temperature of the constant temperature oven is 25 to 100°C, the power supply is set to -20 to -30kV, and the charging time is 10 to 60 minutes.

[0040] The beneficial effects of this invention are:

[0041] 1. The present invention provides a multi-scale enhanced dipole shell-core structure electret microsphere and its composite bio-electret. The core material of the shell-core structure electret microsphere has different dipoles. A stable shell-core structure is formed by using macromolecular polysaccharides as wall materials. The wall materials can stabilize the dipole charge of the core material and have good biocompatibility, making it difficult for the dipole charge of the core material to depolarize.

[0042] 2. The shell-core electret microspheres designed and constructed in this invention can be composited with different biomaterials according to different tissue engineering needs. The composite material is also placed in a self-made dipole PDMS chamber for thermal polarization to obtain a composite bioelectrode with enhanced dipoles. The dipoles of the shell-core electret microspheres in the polymer matrix are enhanced by secondary polarization. At the same time, more cavity dipole charge traps are introduced at the junction of the crystalline and amorphous regions of the matrix material. Secondly, chain entanglement and chain curling occur between the electret microspheres and the polymer molecular chains, generating physical defects at the interface and forming a large number of interface cavity dipole charge traps.

[0043] 3. In this invention, the PDMS silicone dipole chamber is composed of PDMS and a polypropylene box. PDMS has a high breakdown voltage and good elasticity, while the polypropylene box can provide a stable storage space. Using PDMS as a raw material to make dipole molds can provide stable polarization voltage and polarization temperature, which solves the problem of easy breakdown of polymer materials under high voltage. At the same time, it can meet the polarization of dipole materials with different shell-core structures and their composite materials, thus broadening the dipoleization of biopolymer materials.

[0044] 4. In this invention, a composite bio-electropor composed of electret microspheres with a physical-chemical-physical multi-level cross-linked network structure formed by polyvinyl alcohol and polyacrylamide is used as an example, but this method is also applicable to other biocompatible polymer materials.

[0045] 5. The method and equipment used in this invention are simple. The self-made dipole chamber successfully avoids the problem that conventional biopolymer materials have low breakdown voltage and cannot be polarized at high voltage, thus broadening the diversity of bioelectrode materials. Moreover, the preparation process is simple and low-cost, which is conducive to large-scale production. In addition, the drugs used in this invention are all low-toxicity or non-toxic reagents and have little environmental pollution. Attached Figure Description

[0046] Figure 1 A flowchart illustrating the preparation method of multi-scale reinforced dipole core microspheres according to the present invention;

[0047] Figure 2 Optical microscope images (5 μm) of core-shell structure electret microspheres at different scales;

[0048] Figure 3 The images are scanning electron microscope (SEM) images (500 nm) of the shell-core structure electret microspheres, where a is the surface morphology of the core material palm wax and b is the surface morphology of the shell-core structure microspheres.

[0049] Figure 4 The surface charge density decay diagram of the composite biological electret;

[0050] Figure 5 The electrical signal generated by the composite biological electret under different external force cyclic compression. Detailed Implementation

[0051] The following specific implementation examples further illustrate the embodiments of the present invention. These implementation examples are merely illustrative and not intended to limit the scope of the invention. Furthermore, various equivalent modifications made to the present invention by those skilled in the art after reading the teachings of this invention also fall within the scope claimed in the claims of this application.

[0052] Doping polymer matrices with nanofillers is one of the effective ways to improve dipole charge storage density. This method is highly effective and simple to operate, thus possessing significant research value and application prospects for enhancing the dipole charge density of electrets. The addition of nanoparticles introduces more cavitation charge traps at the interface between the crystalline and amorphous regions of the matrix material. Secondly, chain entanglement and coiling occur between nanoparticles and polymer molecular chains, generating physical defects at the interface and forming numerous interfacial cavity traps. Furthermore, chemical bonding on the nanoparticle surface also generates dipole charge traps, including covalent bonds, ionic bonds, coordination bonds, hydrogen bonds, electrostatic interactions, hydrophilic-hydrophobic balance, and van der Waals forces. The doping of nanofillers provides more dipole charge traps, thereby increasing the dipole charge density.

[0053] To this end, the present invention provides a multi-scale reinforced dipole shell-core microsphere, a preparation method, and a composite bio-electropor. The shell-core structure electropor microsphere can be designed and constructed to be combined with different biomaterials according to different tissue engineering needs. The composite material is also placed in the dipole chamber for thermal polarization to obtain a composite bio-electropor with reinforced dipoles. It can be applied to fields such as biosensing, biomimetic skin, medical dielectric materials, and tissue repair.

[0054] In this process, micro- and nano-scale microspheres are prepared as the core material using an emulsion phase separation method. Biomolecules serve as the wall material, forming a core-shell structure through complex condensation. These core-shell microspheres are then placed in a self-made PDMS dipole chamber and thermally polarized to obtain multi-scale electret microspheres with a core-shell structure. The designed and constructed core-shell electret microspheres can be used as "dipole-like" physical dopants in different biopolymers. Thermal polarization of the composite biomaterials containing these "dipole-like" dopants yields composite bioelectrodes with enhanced dipoles. The core-shell electret microspheres in the composite material can increase the dipole charge trapping density through the nanoparticle effect, thereby improving the dipole charge storage density. The polymer cross-linking network in the composite material forms a "locked-in" structure for the "dipole-like" dopants, improving the stability of the matrix dipole charge. The thermal polarization method involves cooling and "freezing" the dipole charges within the orientation matrix under high electric and temperature fields and sustained electric field action. This preparation method is simple, low-cost, produces high dipole charge density, good charge stability, and good biocompatibility. The prepared shell-core electret microspheres and their composite bio-electrodes exhibit good dipole charge stability and their surface charge changes can be modulated by external stimuli (such as stress changes and ultrasound stimulation). This is of great significance for studying the mechanisms by which external electret states regulate endogenous electret states in organisms and for developing new tissue engineering treatments. It can also be applied in fields such as biosensing, biomimetic skin, medical dielectric materials, and tissue repair.

[0055] Specifically, the technical solution of this invention first provides a method for preparing multi-scale reinforced dipole core-shell microspheres, such as... Figure 1 As shown, it includes:

[0056] Step 101: Preparation of core-shell structured microspheres

[0057] Shell-core structured microspheres were prepared by emulsion phase separation and complex coagulation. Under low-speed mechanical stirring, a certain amount of material with dipolar properties was placed in a 500 mL three-necked flask containing 250 mL of a 1 wt%–2 wt% gum arabic aqueous solution. The system was placed in a water bath and slowly heated until completely melted under stirring. The stirring speed was increased to increase shear force, reaching 1000–1200 r / min, and the emulsification time was maintained for 15–30 min. While maintaining stirring, the system temperature was rapidly reduced to 50 °C. 100 mL of a 1% (w / v) chitosan acetate solution was slowly added under stirring, followed by a slow dropwise addition of a 10% acetic acid solution. The pH was adjusted to the isoelectric point of chitosan, which was approximately 4.0. The reaction was allowed to proceed for 30 min, allowing the -NH4+ groups of chitosan in the solution to reach their final concentration. 3+ Positive charge and gum arabic -COO - Negative charges are fully combined. Finally, the mixture is placed in an ice-water bath and cooled to 0°C. A certain amount of 2% glutaraldehyde is added, and the mixture is slowly crosslinked and thoroughly mixed for 30 minutes. The temperature is then rapidly increased to 50°C, and the crosslinking reaction continues for 60 minutes, allowing the chitosan to completely crosslink under the action of glutaraldehyde to form a stable wall material. The mixture is then vacuum filtered, centrifuged and washed 3-5 times to thoroughly remove uncoated chitosan. Finally, it is freeze-dried in a freeze dryer at -50°C and 10 Pa for 24 hours to obtain shell-core structured microspheres.

[0058] Step 102: Preparation of PDMS Dipolar Chamber

[0059] Weigh out an appropriate amount of polydimethylsiloxane and add 1%-5% (by mass) of curing agent to obtain PDMS prepolymer. Defoam at 25℃ by ultrasonication for 1-2 hours. Place a portion of the PDMS silicone prepolymer in a 10.0cm diameter, 10mm high polytetrafluoroethylene (PTFE) mold and cure in a 50℃-60℃ constant temperature oven for 24 hours as a substrate. The cured silicone thickness is approximately 2.5mm. Place the chamber (a 7.0cm inner diameter, 5mm high polypropylene box) and the PDMS silicone prepolymer together in the substrate-covered PTFE mold and cure in a 50℃-60℃ constant temperature oven for 24 hours. The dipole chamber is formed by selecting PDMS, which has high breakdown strength and good elasticity, and the polypropylene box, which also has excellent electret properties. The high breakdown strength of PDMS provides a stable high field voltage and polarization temperature for the dipole mold, while the polypropylene box provides storage space for quasi-electret materials.

[0060] Step 103: Preparation of core-shell electret microspheres

[0061] Open the polypropylene chamber from step two, place the shell-core structured microspheres prepared in step three inside, cover the chamber, and seal it with the prepared PDMS silicone prepolymer. Let it cure in a constant temperature oven at 50℃ for 24 hours. Select two thermally polarized electrodes with a diameter of 8.0 cm, sandwich the PDMS mold containing the shell-core structured microspheres between the two electrodes, and place them together in the constant temperature oven. Connect the electrodes to the power supply of the thermal polarization charging device, set the oven temperature to 25–100℃, the high voltage power supply to -20–-30 kV, and the charging time to 10–60 min, keeping the voltage constant during polarization. Afterwards, multi-scale reinforced dipole shell-core structured electret microspheres are obtained.

[0062] The present invention provides a multi-scale reinforced dipole shell-core microsphere, which is prepared using the above method.

[0063] The present invention also provides a composite bio-electroporate, the preparation method of which is as follows:

[0064] A certain amount of the multi-scale reinforced dipole core-shell microspheres prepared in step three were taken and screened to obtain microspheres with a particle size of 1-10 micrometers. These microspheres were then incorporated into the bioactive macromolecular matrix through physical blending. During this process, the microspheres were continuously dispersed and homogenized by ultrasonic stirring. Finally, the microspheres were shaped and processed according to different requirements. The processed composite material was placed in the electret chamber of step four. Two thermally polarized electrodes with a diameter of 8.0 cm were selected, and the PDMS mold containing the composite material was sandwiched between the two electrodes and placed in a constant temperature oven. The electrodes were connected to a thermally polarized charging power supply. The temperature of the constant temperature oven was set to 25-100℃, the high voltage power supply was set to -20 to -30 kV, and the charging time was 10-60 min. The voltage remained constant during the polarization process, resulting in a composite bio-electroporation with core-shell structure electret microspheres reinforcing the dipole.

[0065] Here, the core material of the shell-core electret microspheres has different dipoles. A stable shell-core structure is formed by using macromolecular polysaccharides as wall materials. The wall materials can stabilize the dipole charge of the core material and have good biocompatibility, making it difficult for the dipole charge of the core material to depolarize. The core material used is not limited to the palm wax microspheres in the examples, but can also be inorganic materials with excellent electret properties, such as barium titanate, perovskite, silica, and nano-hydroxyapatite, all of which can be used in this invention. The wall material used is not limited to chitosan in the examples, but can also be other polysaccharide polymers with good biocompatibility.

[0066] Simultaneously, the designed and constructed core-shell electret microspheres can be used as "dipole-like" physical dopants in different biopolymers. Thermal polarization treatment of the composite biomaterials containing "dipole-like" microspheres yields composite bioelectropories with enhanced dipoles. The core-shell electret microspheres in the composite material can increase the dipole charge trapping density and improve the dipole charge storage density through the nanoparticle effect. The polymer cross-linking network in the composite material forms a "locked-in" structure for the "dipole-like" microspheres, improving the stability of the matrix dipole charge. The thermal polarization method involves cooling and "freezing" the dipole charges within the orientation matrix under high electric and temperature fields and sustained electric field action.

[0067] The dipole chamber is composed of PDMS and a polypropylene box. PDMS has a high breakdown voltage and good elasticity, while the polypropylene box provides a stable storage space. Using PDMS as a raw material to make dipole molds can provide stable polarization voltage and polarization temperature, which solves the problem of easy breakdown of polymer materials under high voltage. At the same time, it meets the polarization requirements of dipole materials with different shell-core structures and their composites, thus broadening the dipoleization of biopolymer materials.

[0068] In addition, the polymer material in the composite bio-electrode can theoretically be a biocompatible biomacromolecule, such as chitosan, gelatin, bacterial cellulose, sodium alginate, biodegradable polyurethane, etc., and can be one or more of these composites. The interaction between polymers can further "lock" the shell-core electret microspheres and enhance the charge stability of the entire matrix.

[0069] Example 1

[0070] Step 1: Preparation of surfactant aqueous solution

[0071] Add 200 mL of deionized water to a 1 L beaker; add the surfactant gum arabic at a water mass fraction of 2%, and dissolve it completely under high shear force until it becomes colorless and clear.

[0072] Step 2: Preparation of chitosan acetate solution

[0073] Measure 2 mL of glacial acetic acid and dissolve it in 98 mL of aqueous solution to prepare a 2% (V / V) glacial acetic acid solution. Weigh a certain amount of the prepared glacial acetic acid solution of low viscosity (<200 mPa.s) chitosan and prepare a 1% (W / V) chitosan acetic acid solution. Place the solution in a refrigerator at 4℃ and let it stand to remove air bubbles.

[0074] Step 3: Preparation of core-shell structured microspheres

[0075] Chitosan / carnauba wax shell-core structured microspheres were prepared by emulsion phase separation and complex coagulation. Under low-speed mechanical stirring, 5g of carnauba wax was added to 250mL of the gum arabic solution from step one and placed in a 500mL three-necked flask. The system was then placed in a water bath and slowly heated to 85℃ with stirring until the carnauba wax was completely melted. The stirring speed was increased to increase shear force, reaching 1200r / min, and the emulsification time was maintained for 15min. While maintaining stirring, the system temperature was rapidly reduced to 50℃. 100mL of the 1% (w / v) chitosan acetate solution prepared in step two was slowly added with stirring, followed by the slow addition of 10% acetic acid solution to adjust the pH to 4.0. The reaction was allowed to proceed for 30min, allowing the -NH4+ groups of chitosan in the solution to condense. 3+ Positive charge and gum arabic -COO - The negative charges fully combine. Finally, the mixture is placed in an ice-water bath to cool to 0°C, a certain amount of 2% glutaraldehyde is added, and the mixture is slowly cross-linked and cured for 30 minutes. The temperature is then raised to 50°C, and the cross-linking reaction continues for 60 minutes. The mixture is then vacuum filtered, centrifuged and washed 5 times, and finally freeze-dried in a freeze dryer at -50°C and 10 Pa for 24 hours to obtain shell-core structured microspheres.

[0076] Step 4: Preparation of PDMS Dipolar Chamber

[0077] Weigh an appropriate amount of polydimethylsiloxane and add 1%-5% curing agent by mass to obtain PDMS prepolymer. Defoam at 25℃ by ultrasonication for 1-2 hours. Place a portion of the PDMS silicone prepolymer in a polytetrafluoroethylene mold with a diameter of 10.0cm and a height of 10mm. Let it stand and cure in a constant temperature oven at 50℃-60℃ for 24 hours as a substrate. The thickness of the cured silicone is about 2.5mm. Place the small chamber (a polypropylene box with an inner diameter of 7.0cm and a height of 5mm) and the PDMS silicone prepolymer together in a polytetrafluoroethylene mold with a substrate. Let it stand and cure in a constant temperature oven at 50℃-60℃ for 24 hours.

[0078] Step 5: Preparation of core-shell electret microspheres

[0079] Open the polypropylene chamber from step four, place the shell-core structured microspheres prepared in step three inside, cover the chamber, seal it with the prepared PDMS silicone prepolymer, and let it stand and cure in a constant temperature oven at 50℃ for 24 hours. Select two thermally polarized electrodes with a diameter of 8.0cm, sandwich the PDMS mold containing the shell-core structured microspheres between the two electrodes, and place them together in the constant temperature oven. Connect the electrodes to the power supply of the thermally polarized charging device, set the temperature of the constant temperature oven to 60℃, the high voltage power supply to -20kV, and the charging time to 30min. The voltage remains constant during the polarization process.

[0080] Step Six: Preparation of Polyvinyl Alcohol-Based Composite Bio-Electropor with Core-Shell Structure Electroporated Microspheres Reinforced by Dipole

[0081] A certain amount of the core-shell electret microspheres prepared in step three were taken and screened to obtain microspheres with a particle size of 1-10 micrometers. These microspheres were then incorporated into a 30wt% polyvinyl alcohol matrix through physical blending. During this process, the microspheres were continuously dispersed and homogenized using ultrasonic stirring. Finally, the microspheres were molded according to different requirements. The processed composite material was placed in the electret chamber of step four and connected to a thermally polarized electrode. A PDMS mold containing the composite material was sandwiched between the two electrodes and placed in a constant temperature oven. The electrodes were connected to a thermally polarized charging power supply. The oven temperature was set to 60℃, the high-voltage power supply to -20kV, and the charging time to 60min. The voltage remained constant during polarization, resulting in a polyvinyl alcohol-based composite bioelectrode with a core-shell electret microsphere-reinforced dipole.

[0082] Example 2

[0083] Step 1: Preparation of surfactant aqueous solution

[0084] Add 200 mL of deionized water to a 1 L beaker; add the surfactant gum arabic at a water mass fraction of 2%, and dissolve it completely under high shear force until it becomes colorless and clear.

[0085] Step 2: Preparation of chitosan acetate solution

[0086] Measure 2 mL of glacial acetic acid and dissolve it in 98 mL of aqueous solution to prepare a 2% (V / V) glacial acetic acid solution. Weigh a certain amount of the prepared glacial acetic acid solution of low viscosity (<200 mPa.s) chitosan and prepare a 1% (W / V) chitosan acetic acid solution. Place the solution in a refrigerator at 4℃ and let it stand to remove air bubbles.

[0087] Step 3: Preparation of core-shell structured microspheres

[0088] Chitosan / carnauba wax shell-core structured microspheres were prepared by emulsion phase separation and complex coagulation. Under low-speed mechanical stirring, 5g of carnauba wax was added to 250mL of the gum arabic solution from step one and placed in a 500mL three-necked flask. The system was placed in a water bath and slowly heated to 85℃ under stirring to completely melt the carnauba wax. The stirring speed was increased to increase shear force, and the stirring speed was increased to 800r / min, maintaining the emulsification time for 15min. While maintaining stirring, the system temperature was rapidly reduced to 50℃. 50mL of the 1% (w / v) chitosan acetate solution prepared in step two was slowly added under stirring, followed by the slow dropwise addition of 10% acetic acid solution to adjust the pH to 4.0. The reaction was allowed to proceed for 30min, allowing the -NH4+ groups of chitosan in the solution to condense. 3+ Positive charge and gum arabic -COO- The negative charges fully combine. Finally, the mixture is placed in an ice-water bath to cool to 0°C, a certain amount of 2% glutaraldehyde is added, and the mixture is slowly cross-linked and cured for 30 minutes. The temperature is then raised to 50°C, and the cross-linking reaction continues for 60 minutes. The mixture is then vacuum filtered, centrifuged and washed 5 times, and finally freeze-dried in a freeze dryer at -50°C and 10 Pa for 24 hours to obtain shell-core structured microspheres.

[0089] Step 4: Preparation of PDMS Dipolar Chamber

[0090] Weigh an appropriate amount of polydimethylsiloxane and add 1%-5% curing agent by mass to obtain PDMS prepolymer. Defoam at 25°C by ultrasonication for 2 hours. Place a portion of the PDMS silicone prepolymer in a polytetrafluoroethylene mold with a diameter of 10.0 cm and a height of 10 mm. Let it stand and cure in a constant temperature oven at 50°C for 24 hours as a substrate. The thickness of the cured silicone is about 2.5 mm. Place the small chamber (a polypropylene box with an inner diameter of 7.0 cm and a height of 5 mm) and the PDMS silicone prepolymer together in a polytetrafluoroethylene mold with a substrate. Let it stand and cure in a constant temperature oven at 50°C for 24 hours.

[0091] Step 5: Preparation of core-shell electret microspheres

[0092] Open the polypropylene chamber from step four, place the shell-core structured microspheres prepared in step three inside, cover the chamber, seal it with the prepared PDMS silicone prepolymer, and let it stand and cure in a constant temperature oven at 50℃ for 24 hours. Select two thermally polarized electrodes with a diameter of 8.0cm, sandwich the PDMS mold containing the shell-core structured microspheres between the two electrodes, and place them together in the constant temperature oven. Connect the electrodes to the power supply of the thermally polarized charging device, set the temperature of the constant temperature oven to 70℃, the high voltage power supply to -20kV, and the charging time to 30min. The voltage remains constant during the polarization process.

[0093] Step Six: Preparation of Polyvinyl Alcohol / Polyacrylamide Composite Bio-electrode with Core-Shell Structure Electrode Microspheres Reinforced by Dipole

[0094] A certain amount of the shell-core electret microspheres prepared in step three were taken and screened to a particle size of 1-10 micrometers. The microspheres were then incorporated into 50g of 10wt% polyvinyl alcohol solution matrix through physical blending. During this process, the microspheres were continuously dispersed by ultrasonic stirring to ensure uniformity. The beaker was placed in an ultrasonic machine for ultrasonication for 15 minutes. During ultrasonication, the beaker was continuously shaken to ensure uniform dispersion of the microspheres in the PVA molecular network structure. Subsequently, 8g of acrylamide monomer was dissolved in the above solution to form a homogeneous solution. Then, ammonium persulfate (56mg), N,N′-methylenebisacrylamide (80mg), and N,N,N′,N′-tetramethylethylenediamine (56mg) were added as initiator. The solution was then uniformly spread on a clean and dry glass plate by casting to form a film. The sample was placed in a 60℃ oven for a full crosslinking reaction for 1 hour. Cut into several small circular pieces with a diameter of 20mm, place them in the dipole chamber for thermal polarization treatment, and then place the dipole chamber under a high-temperature thermal polarization charging device for charging. Set the temperature to 70℃, the voltage to -20kV, and the charging time to 60min. Then keep the voltage constant and cool down to room temperature to complete the electret process.

[0095] It should be noted that: the above embodiments use chitosan as the wall material and palm wax as the core material to illustrate the shell-core structure of electret microspheres, but this method is also applicable to other biocompatible polysaccharide polymers. For example... Figure 2 As shown, the shell-core microspheres prepared according to the examples, when observed under an optical microscope, reveal that the microspheres have a relatively uniform particle size, with a size scale between micrometers and nanometers; Figure 3 As shown, the surface structure of the palm wax core microspheres is smooth and continuous, while the surface structure of the microspheres becomes rough and has more wrinkles after being coated with chitosan wall material. This also shows that the chitosan wall material was successfully composited onto the surface of the core material to obtain stable shell-core microspheres.

[0096] Application Example 1: The surface charge density of the shell-core structure electret microsphere dipole-reinforced polyvinyl alcohol-based composite bioelectrode was tested using a surface charge amplifier.

[0097] like Figure 4 As shown in Example 1, the surface charge density of the polyvinyl alcohol-based composite bioelectrode reinforced with a shell-core structure electret microsphere dipole was monitored. Initially, the charge density decayed rapidly due to environmental factors, but after 8 days, its surface charge density stabilized at 21 nC / m². 2 This indicates that it has good charge stability.

[0098] Application Example 2: Test of the biomechanical-electric response of a core-shell structured electret microsphere dipole-reinforced polyvinyl alcohol / polyacrylamide composite bioelectrode.

[0099] like Figure 5As shown in Example 2, the output of the electrical signal of the polyvinyl alcohol / polyacrylamide composite bioelectrode reinforced by the shell-core structure electret microsphere dipole was tested by cyclic compressive strain. The results show that a stable output electrical signal can be generated under cyclic strain, indicating that it has a certain electromechanical response.

[0100] This invention utilizes a suitable method to dissolve or melt materials with different dipole polarities to form an oil phase. This oil phase is then incorporated into a water-in-oil or water-in-oil system within an emulsion using water as the medium. Different polysaccharide macromolecules are selected as wall materials, and a stable shell-core structure microsphere is formed by adding a crosslinking agent. The shell-core microspheres are then separated and purified using steps such as stirring and washing, ultrasonic dispersion, and centrifugation. A dipole chamber is fabricated using PDMS and polypropylene. The shell-core microspheres are then thermally polarized within this self-made dipole chamber to obtain multi-scale shell-core electret microspheres. Based on this, the multi-scale shell-core electret microspheres can be physically doped into biopolymer materials to obtain reinforced dipole composite bioelectrodes through secondary polarization.

[0101] In summary, in this invention, the core material is prepared using a micro / nanoscale microsphere obtained through an emulsion phase separation method. Biomolecules serve as the wall material, forming a core-shell structure through complex condensation. Multi-scale electret microspheres with a core-shell structure are obtained through thermal polarization treatment within a self-made PDMS dipole cavity. The designed and constructed core-shell electret microspheres can be used as "dipole-like" physical dopants in different biopolymers. Thermal polarization treatment of the composite biomaterial containing "dipole-like" materials yields a composite bioelectrode with enhanced dipoles. The core-shell electret microspheres in the composite material can increase the dipole charge trapping density and improve the dipole charge storage density through the nanoparticle effect. The polymer crosslinking network in the composite material forms a "lock-in" structure for the "dipole-like" components, improving the stability of the matrix dipole charge. The thermal polarization method involves cooling and "freezing" the dipole charges within the orientation matrix under high electric and temperature fields and sustained electric field action. This preparation method is simple, low-cost, produces high dipole charge density, good charge stability, and good biocompatibility. The prepared shell-core electret microspheres and their composite bio-electropories exhibit good dipole charge stability and their surface charge changes can be modulated by external stimuli (such as stress changes or ultrasound stimulation). This is of great significance for studying the mechanisms by which external electret states regulate endogenous electret states in organisms and for developing new tissue engineering treatments. It can also be applied in fields such as biosensing, biomimetic skin, medical dielectric materials, and tissue repair.

[0102] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. For those skilled in the art, any changes, modifications, substitutions, and variations made to the embodiments based on the teachings of the present invention without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing multi-scale reinforced dipole core-shell microspheres, characterized in that, The preparation method includes: Step 1: Prepare shell-core structured microspheres by emulsion phase separation and complex condensation method; Step 2: Prepare the polydimethylsiloxane dipole chamber; Step 3: Place the shell-core structured microspheres into the polydimethylsiloxane dipole chamber and seal the opening. After curing, perform polarization treatment and then remove them from the polydimethylsiloxane dipole chamber to obtain multi-scale reinforced dipole shell-core microspheres. Specifically, step 1 includes: Step 1.1: Under low-speed mechanical stirring, take a certain amount of material with dipolar properties and place it in a container with the gum arabic aqueous solution and place the whole container in a water bath. Heat under stirring until completely melted. Step 1.2: Increase the stirring speed and maintain emulsification. Under stirring conditions, rapidly cool down and add chitosan acetate solution, followed by dropwise addition of acetic acid solution to adjust the pH to the isoelectric point of chitosan. Step 1.3: Cool down the whole process, then add a certain amount of glutaraldehyde, slowly crosslink and mix thoroughly, then quickly heat up and continue the crosslinking reaction; Step 1.4: After vacuum filtration and centrifugal washing, the microspheres with shell-core structure are freeze-dried for a period of time to obtain the microspheres. Specifically, step 3 includes: Step 3.1: Place the shell-core structured microspheres into the polydimethylsiloxane dipole chamber, seal the opening, and then let it stand and cure in a constant temperature oven; Step 3.2: Place the PDMS mold containing the core-shell structured microspheres between two thermally polarized electrodes and put them together in a constant temperature oven; Step 3.3: The electrode is connected to the power supply of the thermal polarization charging device for polarization treatment, and then taken out from the polydimethylsiloxane dipole chamber to obtain multi-scale reinforced dipole shell-core microspheres.

2. The preparation method according to claim 1, characterized in that: In step 1.1, the weight percentage of the gum arabic aqueous solution is 1 wt% - 2 wt%. In step 1.2, the stirring speed is increased to 1000-1200 r / min, and the emulsification time is maintained for 15-30 min. Under stirring conditions, the temperature is rapidly reduced to 50 ℃, and 1% W / V chitosan acetate solution is slowly added under stirring conditions, followed by 10% acetic acid solution. The pH is adjusted to the isoelectric point of chitosan, and the reaction is carried out for 30 min. In step 1.3, the overall temperature is lowered to 0 ℃, a certain amount of 2% glutaraldehyde is added, the cross-linking is slowly carried out and fully mixed for 30 min, the temperature is rapidly raised to 50 ℃, and the cross-linking reaction is continued for 60 min. In step 1.4, the food is placed in a freeze dryer at -50 ℃ and 10 Pa for freeze drying for 24 hours.

3. The preparation method according to claim 1, characterized in that, Step 2 specifically includes: Step 2.1: Weigh a certain amount of polydimethylsiloxane, add curing agent and stir thoroughly to obtain polydimethylsiloxane silicone prepolymer, and then perform defoaming treatment; Step 2.2: Take a portion of the polydimethylsiloxane silicone prepolymer and place it in a polytetrafluoroethylene mold. Let it stand and cure in a constant temperature oven to form a layer of polydimethylsiloxane substrate at the bottom of the polytetrafluoroethylene mold. Step 2.3: Place the polypropylene box and a portion of the polydimethylsiloxane silicone prepolymer together in a polytetrafluoroethylene mold with the polydimethylsiloxane substrate, and let it stand and cure in a constant temperature oven to obtain a polydimethylsiloxane dipole chamber.

4. The preparation method according to claim 3, characterized in that: In step 2.1, the mass fraction of the curing agent is 1%-5%; In steps 2.2 and 2.3, the conditions for static curing are: static curing in a constant temperature oven at 50 ℃-60 ℃ for 24 h; In step 2.3, the inner diameter of the polypropylene box is 7.0 cm and the height is 5 mm.

5. The preparation method according to claim 4, characterized in that, In step 3.3, the temperature of the constant temperature oven is 25 ~ 100 ℃, the power supply is set to -20 ~ -30 kV, and the charging time is 10 ~ 60 min.

6. A multi-scale reinforced dipole shell-core microsphere, characterized in that, The multi-scale reinforced dipole shell-core microspheres are prepared using the preparation method according to any one of claims 1 to 5.

7. A composite bio-electroporium with a core-shell structure and dipole-reinforced electret microspheres, characterized in that, The composite bio-electroporium with shell-core structure electret microspheres and dipole reinforcement is obtained based on the preparation of multi-scale reinforced dipole shell-core microspheres according to claim 6, wherein the preparation method of the composite bio-electroporium with shell-core structure electret microspheres and dipole reinforcement is as follows: Step 1: Take a certain amount of the multi-scale reinforced dipole shell-core microspheres, screen the particle size and then dope them into the bioactive macromolecular matrix. After ultrasonic stirring to disperse them evenly, they are then shaped and processed to obtain composite material microspheres. Step 2: Prepare the polydimethylsiloxane dipole chamber; Step 3: Place the composite material microspheres into the polydimethylsiloxane dipole chamber and seal the opening. After curing, perform polarization treatment and then remove them from the polydimethylsiloxane dipole chamber to obtain a composite bio-electrode with a core-shell structure electret microsphere-reinforced dipole.

8. The composite bio-electroporium according to claim 7, characterized in that, Step 3 specifically includes: Step 3.1: Place the composite material microspheres into the polydimethylsiloxane dipole chamber, seal the opening, and then let it stand and cure in a constant temperature oven; Step 3.2: Place the PDMS mold containing the composite material between two thermally polarized electrodes and put them together in a constant temperature oven; Step 3.3: The electrode is connected to the power supply of the thermal polarization charging device for polarization treatment, and then taken out from the polydimethylsiloxane dipole chamber to obtain a composite bio-electrode with a core-shell structure electret microsphere reinforced dipole.

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