Antibacterial dressing based on magneto-rheological and magneto-thermal synergistic effect and preparation method thereof

Abstract

The invention discloses an antibacterial dressing based on a magnetorheological and magnetocaloric synergistic effect, the antibacterial dressing comprises a dressing substrate, specific magnetic particles and specific magnetocaloric particles, the specific magnetic particles are orderly arranged on the surface of the dressing substrate, and the specific magnetocaloric particles are uniformly distributed in the dressing substrate; the length of the specific magnetic particles is 4 [mu] m, the width of the specific magnetic particles is 2 [mu] m, the height of the specific magnetic particles is 10 [mu] m, and the distance between the specific magnetic particles is 1 [mu] m. The antibacterial dressing disclosed by the invention is based on a magneto-rheological effect and a magnetothermal effect, so that collaborative regulation and control on a force-thermal microenvironment of a wound surface are realized, and a physical condition with an optimal antibacterial effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic materials, and in particular to an antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal effects and a preparation method thereof. Background Art

[0002] At present, bacterial resistance has become a global concern. Infections caused by resistant bacteria have become a new challenge for anti-infection treatment in the new century and are the main threat to human health and life today. Clinically, skin defects caused by trauma, burns, venous ulcers and diabetic ulcers can cause serious bacterial infections, which bring great pain and heavy medical burden to patients. Bacterial infection is the main obstacle to wound healing. Researchers have invested a lot of energy in finding new antibiotics to solve the problem of bacterial resistance. However, the speed of developing new antibiotics is far behind the speed of bacterial resistance; what is more serious is that bacteria continue to mutate, and when new antibiotics are used, they continue to induce resistance to new antibiotics, forming a vicious circle. Due to the emergence and rapid spread of drug-resistant strains, some pan-resistant strains have even become "untreatable", making the rate of infectious diseases still quite high and the failure rate of empirical medication increased. Summary of the invention

[0003] The present invention proposes an antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal, which is used to solve the problem that the current antibacterial dressing is easy to cause bacteria to mutate and produce drug resistance, thereby losing the antibacterial effect.

[0004] The present invention provides the following technical solutions:

[0005] In the first aspect, the present specification provides an antibacterial dressing based on the synergistic effect of magnetorheology and magnetocaloric effect, comprising a dressing base, specific magnetic particles, and specific magnetocaloric particles, wherein: the specific magnetic particles are arranged in an orderly manner on the surface of the dressing base, and the specific magnetocaloric particles are uniformly distributed in the dressing base; the length of the specific magnetic particles is 4 μm, the width of the specific magnetic particles is 2 μm, the height of the specific magnetic particles is 10 μm, and the spacing between the specific magnetic particles is 1 μm.

[0006] Optionally, the specific magnetic particles are iron nanowires with a minimum particle size of 500 nm, and the specific magnetocaloric particles are ferroferric oxide particles.

[0007] In a second aspect, the present invention provides a method for preparing the antibacterial dressing, comprising: mixing polydimethylsiloxane and boric acid in a preset ratio, heating and stirring at high temperature to obtain a base liquid; ultrasonically dissolving the base liquid in a chloroform solution, adding specific magnetic particles, specific magnetocaloric particles and carbon nanotubes to obtain a mixture; stirring the mixture under preset temperature conditions, adding iron nanowires, and stirring again to obtain a first homogeneous mixed solution; adding the first homogeneous mixed solution to a first mold, with cylindrical NdFeB permanent magnets fixed at both ends of the first mold; placing the first mold in an oven for curing to obtain a dressing.

[0008] In a third aspect, the present invention provides a method for preparing the antibacterial dressing, comprising: mixing polydimethylsiloxane and boric acid in a preset ratio, heating and stirring at high temperature to obtain a base liquid; ultrasonically dissolving the base liquid in a chloroform solution, adding specific magnetic particles, specific magnetocaloric particles and carbon nanotubes to obtain a mixture; stirring the mixture under preset temperature conditions, adding iron nanowires, and stirring again to obtain a first homogeneous mixed solution; adding the first homogeneous mixed solution to a first mold, with cylindrical NdFeB permanent magnets fixed at both ends of the first mold; placing the first mold in an oven for curing to obtain a dressing; taking a preset mass of the first homogeneous mixed solution, adding iron particles and ferrosoferric oxide particles, and stirring to obtain a second homogeneous mixed solution; placing the dressing at the bottom of a second mold, pouring the second homogeneous mixed solution into the second mold, with cylindrical NdFeB permanent magnets fixed at both ends of the second mold, and placing the second mold in an oven for curing to obtain a double-layer dressing.

[0009] Optionally, after adding specific magnetic particles, specific magnetocaloric particles and carbon nanotubes, it also includes: adding specific diamagnetic metal particles and carbonyl iron particles, the specific diamagnetic metal particles are copper micro-nano particles or silver micro-nano particles, and the carbonyl iron particles are micrometer-sized or nanometer-sized carbonyl iron particles.

[0010] Optionally, taking a preset mass of the first homogeneous mixed solution, adding iron particles and ferroferric oxide particles, and stirring to obtain a second homogeneous mixed solution, specifically comprising: taking a preset mass of the first homogeneous mixed solution, adding iron particles with a diameter of 50 μm and ferroferric oxide particles with a diameter of 100 μm, and stirring for 2 hours to obtain a second homogeneous mixed solution.

[0011] In a fourth aspect, the present invention provides a method for using the antibacterial dressing, comprising: respectively setting an AC coil on both sides of the antibacterial dressing, setting a DC coil above the antibacterial dressing, applying an electric current of a preset frequency to the DC coil, and generating a magnetic field of a preset intensity around the antibacterial dressing.

[0012] Optionally, the preset intensity is greater than the minimum magnetic field intensity that destroys the surface stiffness of bacteria, and the preset frequency is not less than 60 kHz.

[0013] Optionally, the AC coil is a ring-shaped coil, and the inner diameter of the ring-shaped coil is not less than the maximum cross-sectional diameter of the target tissue.

[0014] Optionally, after the DC coil is arranged above the antibacterial dressing, the method further includes: arranging a permanent magnet on the DC coil.

[0015] The antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal provided in an embodiment of the present invention applies a constant magnetic field in a direction perpendicular to the dressing surface. Under the magnetorheological effect, the morphology and stiffness of the dressing surface change to form an outward needle-shaped array structure. This structure has the ability to capture and destroy bacteria, and then remove the bacteria, thereby solving the problem that the existing antibacterial dressings are prone to lose their antibacterial effect due to bacterial mutation and drug resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the internal structure of the dressing in an embodiment of the present invention;

[0017] Figure 2 Schematic diagram of a dressing preparation process according to an embodiment of the present invention;

[0018] Figure 3 A schematic diagram of mechanically controlling magnetorheological effect in an embodiment of the present invention;

[0019] Figure 4 A schematic diagram of temperature rise controlling magnetocaloric effect in an embodiment of the present invention;

[0020] Figure 5 Schematic diagram of a skin heat transfer model under magnetothermal response in an embodiment of the present invention;

[0021] Figure 6 Schematic diagram of the synergistic effect of the dressing in a constant / alternating magnetic field in an embodiment of the present invention;

[0022] Figure 7 Schematic diagram of a dressing surface morphology control experiment in an embodiment of the present invention;

[0023] Figure 8 (a) is a schematic diagram of the micro-nanostructure of the dressing and the attachment of bacteria in an embodiment of the present invention;

[0024] Figure 8 (b) is a schematic diagram of a bacterial cell wall tension model in an embodiment of the present invention;

[0025] Fig. 9 Schematic diagram of a three-dimensional model of the interaction between micro-nano morphology and bacteria in an embodiment of the present invention;

[0026] Fig.10 This is a colony diagram of Escherichia coli after antibacterial treatment in an embodiment of the present invention.

[0027] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of this specification more clear, the technical solutions of this specification will be clearly and completely described below in combination with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of them. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0029] As described herein, the term “including” and various variations thereof may be understood as open-ended terms meaning “including but not limited to,” and the term “one embodiment” may be understood as “at least one embodiment.”

[0030] The inventors have discovered that existing antibacterial dressings are prone to causing bacteria to mutate and develop drug resistance, thereby losing their antibacterial effects. In view of this, in an embodiment of the present invention, a constant magnetic field is applied in a direction perpendicular to the dressing surface, and the morphology and stiffness of the dressing surface change under the magnetorheological effect, forming an outward needle-like array structure, thereby removing bacteria.

[0031] Embodiment 1

[0032] like Figure 1 As shown, an embodiment of the present invention provides an antibacterial dressing based on the synergistic effect of magnetorheology and magnetocaloric effect, including a dressing base, specific magnetic particles, and specific magnetocaloric particles, wherein: the specific magnetic particles are arranged in an orderly manner on the surface of the dressing base, and the specific magnetocaloric particles are uniformly distributed in the dressing base; the length of the specific magnetic particles is 4 μm, the width of the specific magnetic particles is 2 μm, the height of the specific magnetic particles is 10 μm, and the spacing between the specific magnetic particles is 1 μm.

[0033] In a specific implementation, the specific magnetic particles are iron nanowires with a minimum particle size of 500 nm, and the specific magnetocaloric particles are ferroferric oxide particles.

[0034] This antibacterial dressing takes the unique fine micro-nano antibacterial structure of the natural biological surface of insects (such as cicada wings, dragonfly wings, moth eyes, etc.) as the starting point, constructs a bionic micro-nano structural morphology, and has certain characteristics and functions, such as biocompatibility, chemical inertness, toxicity, fatigue strength, wear resistance and corrosion resistance.

[0035] Based on the mechanism of bacterial surface adhesion and biofilm formation, this example studies the Brownian motion of bacteria during the initial adhesion process and the interaction force with the applied surface. In order to achieve the oriented magnetorheological effect in the direction perpendicular to the skin surface and ensure the good oriented magnetization of the magnetic particles, the internal structure design schematic diagram of the dressing used in this example is shown in the figure. Figure 1 As shown. This embodiment uses iron oxide nanowires with a diameter of 100nm and a length of 20μm as magnetic particles, and modifies their surface to achieve better biocompatibility. In order to meet the requirements of the magnetothermal response of the dressing under the alternating magnetic field horizontal to the skin surface, while not being affected by the magnetorheological effect generated by the constant magnetic field perpendicular to the skin surface, this embodiment uses micron- or nano-scale antimagnetic metal particles as magnetically controlled eddy current heat sources (copper or silver micro-nano particles with antibacterial properties) to ensure that the copper and silver particles are not magnetized during the preparation process and remain evenly distributed in the dressing.

[0036] Specifically, Figure 3 The schematic diagram of mechanically controlled magnetorheological effect is shown in the figure. The dressing is placed horizontally in the uniform magnetic field area in the center of the coil, and a sliding magnet is used to achieve a constant magnetic field in the range of 0 to 1000 Gs. Its stiffness change performance, shear hardening performance, rheological properties and magnetostrictive drive performance are tested. The rheological properties and stiffness changes of the surface morphology of the MRE-MT dressing at different shear frequencies, shear strains and temperatures are compared and analyzed, and the modified Bingham model is introduced to characterize the magnetorheological effect of the dressing:

[0037] F(t)=C d e&+F d (E)sgn(e&)-f0=K d (xe)-f0

[0038] Where F(t) is the output force on the dressing surface; C d is the viscous damping coefficient of the dressing; F d (E) is the controllable Coulomb damping force; e is the Bingham unit displacement; x is the dressing surface displacement; K d is the equivalent axial stiffness of the dressing, and f0 is the output force deviation of the dressing.

[0039] Specifically, Figure 4This is a schematic diagram of the temperature rise control magnetocaloric effect. The dressing is placed parallel to the axial middle and end of the induction heating coil. Based on the zero voltage switch (ZVS) induction heating circuit, the Helmholtz coil generates a 60kHz current. The MRE-MT dressing bottom layer particles are heated by heat. The magnetic field strength and frequency are adjusted to control the dressing response between 40 and 45°C (skin safety temperature). The temperature rise performance of the dressing is tested by an infrared imager, and its temperature rise rate and temperature distribution are characterized.

[0040] Specifically, Figure 5 This is a skin heat transfer model under magnetothermal response. For the heat transfer process of the local skin tissue microenvironment, it is assumed that the skin wound surface is multi-layered, homogeneous and isotropic. Considering that the heat generated by blood circulation and metabolic factors will inevitably exchange heat energy with the surrounding tissues, it affects the heat conduction process in the tissues. The Fourier heat transfer model cannot describe the influence of this complex biological phenomenon on heat conduction. Therefore, an improved Pennes bioheat transfer model is proposed to represent it.

[0041] Specifically, Figure 6 The figure is a schematic diagram of the synergistic effect of dressings in a constant / alternating magnetic field. Skin wounds are usually distributed over a certain area on the skin surface. When performing antibacterial treatment on the skin, it is not convenient to set up electromagnetic induction coils in certain physiological parts. Therefore, suitable magnetic field generating devices are studied for different skin parts. Figure 6 As shown in the figure, for the constant magnetic field perpendicular to the application surface for changing the magnetorheological micro-nano morphology stiffness of the dressing, considering the requirements of wound area and magnetic field strength, flexible multi-turn coils, coil arrays, and superimposed responses of coils and permanent magnets are used to achieve this. For the alternating magnetic field horizontal to the application surface for generating magnetothermal temperature rise, the coil alternating magnetic field excitation is realized based on the zero voltage switching (ZVS) induction heating circuit. Considering the spatial limitations such as the wound surface position, length, and cross-sectional size, through-type solenoids, split flexible coils, and their arrays are used to achieve this.

[0042] Specifically, Figure 7 This is a schematic diagram of the dressing surface morphology control experiment. The research foundation shows that the magnetorheological effect is controllable on the surface morphology of the elastomer, and its stiffness can be adjusted according to the magnetic field response, thereby achieving stress regulation of the attachment.

[0043] Specifically, Figure 8 (a) is a schematic diagram of the dressing micro-nanostructure and bacterial attachment. Figure 8(b) is a schematic diagram of the bacterial cell wall tension model. In view of the antibacterial effect, this embodiment further selects more suitable elastomer components, surface morphology structures and dimensions. Mechanical force is generated by the swing of particles with a surface length of 4 μm, a width of 2 μm, a height of 10 μm and a spacing of 1 μm to capture and destroy bacteria, ultimately achieving mechanical intervention on bacteria.

[0044] Specifically, Fig. 9 It is a three-dimensional model of the interaction between micro-nanotopography and bacteria. This embodiment uses a biophysical model to explain the interaction between the surface nanocone structure and bacteria: when bacteria come into contact with the surface of cicada wings, they are divided into two regions, the region in direct contact with the nanopillars and the region suspended between the nanopillars.

[0045] Specifically, Fig.10 In order to take Escherichia coli as an example to illustrate the colony map after antibacterial treatment, this embodiment selects a plate without micro-nano structure, MRE-MT with a micro-nano structure surface of 3μm spacing, MRE-MT with a micro-nano structure surface of 5μm spacing, and MRE-MT with a micro-nano structure surface of 10μm spacing as different experimental groups, and uses a Helmholtz coil as a magnetic field generating device to apply a magnetic field strength of 300mT. The Helmholtz coil is used to generate a current with a frequency of 60kHz to raise the sample temperature to 45°C to ensure the magnetic thermal temperature rise effect of the sample. Finally, the mortality rate of Escherichia coli is calculated, and the survival rate of Escherichia coli on the plate without micro-nano structure is BS=93% The survival rate of Escherichia coli on the surface of MRE micro-nanostructure with a spacing of 10 μm is BS=87%, the survival rate of Escherichia coli on the surface of MRE micro-nanostructure with a spacing of 5 μm is BS=69%, and the survival rate of Escherichia coli on the surface of MRE micro-nanostructure with a spacing of 3 μm is BS=8%. The surface of the micro-nanostructure with a spacing of 3 μm has obvious antibacterial effect, and the present invention has good antibacterial effect against Escherichia coli (1×108CFU / mL) and similar biological binary bacteria, such as Staphylococcus aureus (7.5×106CFU / mL) and Pseudomonas aeruginosa (1.5×108CFU / mL).

[0046] Embodiment 2

[0047] like Figure 2 As shown, an embodiment of the present invention provides a method for preparing an antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal:

[0048] Step 1: Mix polydimethylsiloxane and boric acid in a preset ratio, heat and stir at high temperature to obtain a base liquid.

[0049] Step 2: After the base liquid is ultrasonically dissolved in a chloroform solution, specific magnetic particles, specific magnetocaloric particles and carbon nanotubes are added to obtain a mixture.

[0050] Step 3: Stir the mixture under a preset temperature condition, add iron nanowires, and stir again to obtain a first homogeneous mixed solution.

[0051] Step 4: Add the first homogeneous mixed solution into a first mold, with cylindrical NdFeB permanent magnets fixed at both ends of the first mold.

[0052] Step 5: placing the first mold in an oven for curing to obtain a dressing.

[0053] Step six: an AC coil is disposed on both sides of the dressing, a DC coil is disposed above the dressing, a current of a preset frequency is applied to the DC coil, and a magnetic field of a preset intensity is generated around the dressing.

[0054] The above-mentioned embodiment combines the constant / alternating magnetic field driving method, based on the magnetorheological and magnetocaloric effects, to achieve the coordinated regulation of the wound force-thermal microenvironment to achieve the physical conditions for the best antibacterial effect. By applying a constant magnetic field in a direction perpendicular to the dressing surface, the morphology and stiffness of the dressing surface change under the magnetorheological effect, forming an outward needle-shaped array structure, which has the ability to capture and destroy bacteria, and then remove the bacteria, thereby solving the problem that the existing antibacterial dressings are prone to lose their antibacterial effect due to bacterial mutation and drug resistance.

[0055] Embodiment 3

[0056] like Figure 2 As shown, an embodiment of the present invention provides a method for preparing an antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal:

[0057] Step 1: Mix polydimethylsiloxane and boric acid in a preset ratio, heat and stir at high temperature to obtain a base liquid.

[0058] Step 2: After the base liquid is ultrasonically dissolved in a chloroform solution, specific magnetic particles, specific magnetocaloric particles and carbon nanotubes are added to obtain a mixture.

[0059] Step 3: Stir the mixture under a preset temperature condition, add iron nanowires, and stir again to obtain a first homogeneous mixed solution.

[0060] Step 4: Add the first homogeneous mixed solution into a first mold, with cylindrical NdFeB permanent magnets fixed at both ends of the first mold.

[0061] Step 5: placing the first mold in an oven for curing to obtain a dressing.

[0062] Step 6: Take a preset mass of the first homogeneous mixed solution, add iron particles and ferroferric oxide particles, and stir to obtain a second homogeneous mixed solution.

[0063] Step seven: placing the dressing at the bottom of the second mold, pouring the second homogeneous mixed solution into the second mold, fixing cylindrical NdFeB permanent magnets at both ends of the second mold, placing the second mold in an oven for curing to obtain a double-layer dressing.

[0064] Step eight, respectively set AC coils on both sides of the double-layer dressing, set a DC coil above the double-layer dressing, apply current of a preset frequency to the DC coil, and generate a magnetic field of a preset intensity around the double-layer dressing.

[0065] The above embodiment further processes the single-layer dressing into a double-layer dressing, so that the dressing has a stronger ability to capture and destroy bacteria, and achieves a better antibacterial effect under the same conditions, thereby solving the problem that the existing antibacterial dressings are prone to lose their antibacterial effect due to bacterial mutation and drug resistance.

[0066] Embodiment 4

[0067] like Figure 2 As shown, the embodiment of the present invention also provides a method for preparing an antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal:

[0068] Step 1: PDMS is used as a base material and boric acid is used as a cross-linking agent. The mixture is mixed in different proportions and heated at high temperature and stirred, so that the PDMS is gradually cross-linked by the boric acid to form a base liquid.

[0069] Step 2: Dissolve the base liquid into the chloroform solution by ultrasound, add iron oxide nanowires or silver micro-nanoparticles, and add carbon nanotubes to regulate the conductivity of the dressing.

[0070] Step 3: Stir at 45°C for 1 hour, then add iron nanowires to the mixture and continue stirring for 2 hours to obtain a homogeneous mixed solution, which is then poured into a cylindrical array mold with a diameter of 5 cm and a thickness of 0.5 cm. Cylindrical NdFeB permanent magnets (surface strength of more than 1000 Gs) are fixed at both ends of the mold to allow the magnetic lines to evenly penetrate the mold. Under the action of the magnetic field, the iron nanowires and uncured PDMS mixture will spontaneously assemble along the direction of the magnetic field to form a tightly ordered linear array.

[0071] Step 4: Finally, put the whole into an oven and heat it to 80°C. After curing for 2 hours, the upper layer of MRE-MT dressing is formed. The surface particle size is 4 μm in length, 2 μm in width, and 10 μm in height, and the particle spacing is 1 μm.

[0072] Step 5: Add iron particles with a diameter of 50 μm and ferrosoferric oxide particles with a diameter of 100 μm to the mixture obtained in step 2, stir for 2 hours to obtain a homogeneous mixed solution, place the upper positive mold of the dressing obtained in step 4 at the bottom of the film mold, and pour the mixed solution into the mold, repeat the corresponding steps of steps 3 and 4, and finally obtain the MRE-MT double-layer dressing.

[0073] Step 6: Apply the dressing to the wound surface, and use a flexible multi-turn coil, a coil array, and a superimposed response of the coil and a permanent magnet to generate a constant magnetic field that destroys the surface stiffness of the bacteria in a direction perpendicular to the dressing surface.

[0074] Step 7: Use a through-type solenoid, a split flexible coil and its array to generate an alternating magnetic field with magnetothermal temperature rise in the horizontal direction of the application surface. The Helmholtz coil generates a 60kHz current to provide heat to increase the temperature and further destroy the bacteria.

[0075] The above-mentioned embodiment adds antimagnetic micro-nanoparticles and oriented iron nanowires into the dressing. Under the alternating magnetic field, based on the magnetocaloric effect, the dressing can form eddy currents to achieve the effect of generating a thermal microenvironment. Under a constant magnetic field, the dressing can form a wound microenvironment to achieve an antibacterial effect. In addition, the above-mentioned embodiment uses an alternating magnetic field drive to achieve a thermal microenvironment. By applying a 60kHz current to the Helmholtz coil, an alternating magnetic field parallel to the dressing surface is generated, and magnetic heat is further generated, thereby forming a temperature that is not conducive to the survival of bacteria to ensure the antibacterial effect.

[0076] Embodiment 5

[0077] like Figure 2 As shown, the embodiment of the present invention also provides a method for preparing an antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal:

[0078] PDMS was used as the substrate and boric acid as the cross-linking agent. The mixture was heated and stirred at high temperature, so that PDMS was gradually cross-linked by boric acid to form a base liquid. The base liquid was dissolved into a chloroform solution by ultrasound, and copper or silver micro-nanoparticles were added to adjust the conductivity of the dressing. Carbon nanotubes were added to regulate the conductivity of the dressing. Stirring was performed at 45°C for 1 hour, and then different mass fractions of iron nanowires were added to the mixture and continued to stir for 2 hours to obtain a homogeneous mixed solution, which was poured into a cylindrical mold with a diameter of 5 cm and a thickness of 0.5 cm. Cylindrical NdFeB permanent magnets (surface strength of more than 1000 Gs) were fixed at both ends of the mold to allow the magnetic lines to evenly penetrate the mold. Under the action of the magnetic field, the iron nanowires and the uncured PDMS mixture will spontaneously assemble along the direction of the magnetic field to form a compact and orderly linear array. Finally, the whole was placed in an oven and heated to 80°C, and cured for 2 hours to form an MRE dressing.

[0079] The above embodiment uses PDMS as the base material, which has good safety, non-toxicity and biocompatibility. By applying a constant magnetic field in a direction perpendicular to the dressing surface, the morphology and stiffness of the dressing surface change under the magnetorheological effect, forming an outward needle array structure, which has the ability to capture and destroy bacteria, thereby removing the bacteria.

[0080] The present invention uses magnetorheological effect and magnetothermal effect to carry out antibacterial treatment from two physical directions: vertical and horizontal.

[0081] For the constant magnetic field perpendicular to the dressing surface for changing the magnetorheological micro-nano morphology stiffness of the dressing, in order to achieve the oriented magnetorheological effect in the direction perpendicular to the skin surface and ensure the good oriented magnetization of the magnetic particles, the present invention adopts iron oxide nanowires with a minimum particle size of 500nm as magnetic particles, and modifies their surface to achieve better biocompatibility. Considering the requirements of wound area and magnetic field strength, the present invention adopts flexible multi-turn coils, coil arrays, and superposition responses of coils and permanent magnets to change the morphology stiffness of the dressing surface through a constant magnetic field. The particles with a length of 4μm, a width of 2μm, a height of 10μm, and a spacing of 1μm on the dressing surface will swing accordingly to generate mechanical force, thereby destroying the basic structure of bacteria, so as to ensure the effect of regulating the morphology stiffness of the dressing surface, and establish a magnetorheological effect control mechanism of the dressing based on iron oxide nanowires;

[0082] For the alternating magnetic field horizontal to the dressing surface for generating magnetothermal temperature rise, the present invention realizes coil alternating magnetic field excitation based on a zero voltage switch (ZVS) induction heating circuit, uses a Helmholtz coil to generate a 60kHz frequency current, considers the space limitations such as the wound surface position, length and cross-sectional size, adopts through-type solenoids, split flexible coils and their arrays, and uses a heating circuit to control the dressing to form a temperature that is not conducive to bacterial survival, so as to ensure the effect of magnetothermal temperature rise, and establishes a magnetothermal effect control mechanism for dressings doped with high-conductivity micro-nano particles;

[0083] Furthermore, in response to an alternating magnetic field, heat is generated in the dressing mainly by magnetocaloric particles (iron particles with a diameter of 50 μm and ferrosoferric oxide particles with a diameter of 100 μm), and the conductivity of the dressing is regulated by antimagnetic micron-sized metal particles and carbon nanotubes to ensure that heat is generated mainly by the magnetocaloric particles in response to an alternating magnetic field.

[0084] In summary, the substrate in the embodiment of the present invention adopts PDMS which is non-toxic, tasteless, physiologically inert and has good chemical stability. The alternating magnetic field used has no tissue penetration depth limitation, can be used to treat deep tissues, can selectively kill tumor cells or bacteria, and can achieve precise positioning heat therapy in the physical targeted area. While effectively killing harmful cells or bacteria, it reduces damage to normal tissues. In addition, magnetic heat therapy can also stimulate the body's own immune function and produce a "remote effect". At the same time, the absorption of magnetic field energy by the magnetic heat medium is higher than that of normal tissues of the body, so that the temperature of the lesion site is significantly higher than that of the surrounding healthy tissues, which greatly improves the effectiveness and safety of heat therapy, thereby solving the problem that the existing antibacterial dressings are prone to lose their antibacterial effect due to drug resistance caused by bacterial mutation.

[0085] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0086] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An antibacterial dressing based on the synergistic effect of magnetorheology and magnetothermal, characterized in that: It includes a dressing base, specific magnetic particles, and specific magnetic thermal particles, wherein: The specific magnetic particles are orderly arranged on the surface of the dressing base, and the specific magnetocaloric particles are evenly distributed in the dressing base; The length of the specific magnetic particle is 4 μm, the width of the specific magnetic particle is 2 μm, the height of the specific magnetic particle is 10 μm, and the interval between the specific magnetic particles is 1 μm.

2. The antibacterial dressing according to claim 1, characterized in that: The specific magnetic particles are iron nanowires with a minimum particle size of 500 nm, and the specific magnetocaloric particles are ferroferric oxide particles.

3. A method for preparing the antibacterial dressing according to claim 1, characterized in that: include: The polydimethylsiloxane and boric acid are mixed in a preset ratio, heated and stirred at high temperature to obtain a base liquid; After the base liquid is ultrasonically dissolved in a chloroform solution, specific magnetic particles, specific magnetocaloric particles and carbon nanotubes are added to obtain a mixture; The mixture is stirred at a preset temperature, iron nanowires are added, and the mixture is stirred again to obtain a first homogeneous mixed solution; Adding the first homogeneous mixed solution into a first mold, with cylindrical NdFeB permanent magnets fixed at both ends of the first mold; The first mold is placed in an oven for curing to obtain a dressing.

4. A method for preparing the antibacterial dressing according to claim 1, characterized in that: include: The polydimethylsiloxane and boric acid are mixed in a preset ratio, heated and stirred at high temperature to obtain a base liquid; After the base liquid is ultrasonically dissolved in a chloroform solution, specific magnetic particles, specific magnetocaloric particles and carbon nanotubes are added to obtain a mixture; The mixture is stirred at a preset temperature, iron nanowires are added, and the mixture is stirred again to obtain a first homogeneous mixed solution; Adding the first homogeneous mixed solution into a first mold, with cylindrical NdFeB permanent magnets fixed at both ends of the first mold; placing the first mold into an oven for curing to obtain a dressing; Taking a preset mass of the first homogeneous mixed solution, adding iron particles and ferroferric oxide particles, and stirring to obtain a second homogeneous mixed solution; The dressing is placed at the bottom of the second mold, and the second homogeneous mixed solution is poured into the second mold. Both ends of the second mold are fixed with cylindrical NdFeB permanent magnets. The second mold is placed in an oven for curing to obtain a double-layer dressing.

5. The method according to claim 3 or 4, characterized in that: After adding specific magnetic particles, specific magnetocaloric particles and carbon nanotubes, it also includes: Specific diamagnetic metal particles and carbonyl iron particles are added, wherein the specific diamagnetic metal particles are copper micro-nano particles or silver micro-nano particles, and the carbonyl iron particles are micron-sized or nano-sized carbonyl iron particles.

6. The method according to claim 4, characterized in that Taking a preset mass of the first homogeneous mixed solution, adding iron particles and ferroferric oxide particles, and stirring to obtain a second homogeneous mixed solution, specifically comprising: A preset mass of the first homogeneous mixed solution was taken, and iron particles with a diameter of 50 μm and ferroferric oxide particles with a diameter of 100 μm were added, and stirred for 2 hours to obtain a second homogeneous mixed solution.

7. A method for using the antibacterial dressing as claimed in claim 1, characterized in that: include: An AC coil is arranged on both sides of the antibacterial dressing, and a DC coil is arranged above the antibacterial dressing. A current of a preset frequency is applied to the DC coil to generate a magnetic field of a preset intensity around the antibacterial dressing.

8. The method according to claim 7, characterized in that The preset intensity is greater than the minimum magnetic field intensity that destroys the surface rigidity of bacteria, and the preset frequency is not less than 60 kHz.

9. The method according to claim 7, characterized in that: The AC coil is a ring-shaped coil, and the inner diameter of the ring-shaped coil is not less than the maximum cross-sectional diameter of the target tissue.

10. The method according to claim 7, characterized in that After the DC coil is arranged above the antibacterial dressing, the method further includes: arranging a permanent magnet on the DC coil.

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