MXene functionalized antibacterial self-healing hydrogel and application thereof

Abstract

The invention belongs to the technical field of functional polymer materials, and discloses MXene functionalized antibacterial self-healing hydrogel and application thereof. The hydrogel is obtained by mixing and reacting polydopamine modified MXene powder, modified chitosan and a polyvinyl alcohol solution in a first buffer solution. The dynamic network self-healing conductive hydrogel based on interaction of a dynamic boron ester bond, a Schiff base bond and a non-covalent bond is obtained and can be applied to a flexible strain sensor.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional polymer materials, and more specifically, relates to a MXene functionalized antibacterial self-healing hydrogel and applications thereof. Background Art

[0002] With the advent of the era of artificial intelligence and big data, flexible devices such as human-computer interaction interfaces, implantable physiological signal tracking systems, and medical health testing have developed rapidly. Among them, flexible strain sensors have the dual characteristics of flexibility and conductivity. They can respond to external stress or external stimuli with resistance or capacitance signals, and then monitor human movement or physiological signals. They are widely used in the field of medical health testing.

[0003] Compared with traditional rigid sensors, flexible strain sensors have obvious advantages in stretchability and conformability to external materials, and have great potential in the fields of wearable devices, artificial intelligence, electronic skin, etc. Flexible strain sensors generally fill conductive fillers (graphene, carbon nanotubes, metal nanoparticles) into an elastic gel matrix, but conductive fillers are generally difficult to distribute evenly, which will affect their mechanical properties and detection sensitivity. At the same time, when the flexible main material hydrogel of the flexible strain sensor is damaged by the outside world, the flexible strain sensor will be damaged or even fail, which will affect data collection and subsequent analysis, especially when used in implantable medical devices, and surgical replacement is also involved.

[0004] The concept of self-healing originates from the self-repair and regeneration ability of animal and plant tissues. Introducing it into flexible strain sensors can extend their service life and improve cost-effectiveness.

[0005] In addition, considering the long-term contact with human tissue, good antibacterial properties ensure the safety and health of the use of flexible strain sensors.

[0006] In summary, optimizing the hydrogel network structure, constructing composite hydrogels, improving their basic properties and giving them multifunctional properties are necessary to improve the practical value of flexible strain sensors and broaden their application areas. Therefore, it is urgent to propose a MXene functionalized antibacterial self-healing hydrogel. Summary of the invention

[0007] The purpose of the present invention is to address the deficiencies of the prior art and propose a MXene functionalized antibacterial self-healing hydrogel and its application. The present invention obtains a dynamic network self-healing conductive hydrogel based on dynamic boron ester bonds, Schiff base bonds and non-covalent bond interactions, which can be used in flexible strain sensors.

[0008] In order to achieve the above-mentioned object, the present invention provides a MXene functionalized antibacterial self-healing hydrogel on the one hand, wherein the hydrogel is obtained by mixing and reacting polydopamine-modified MXene powder (MXene@PDA) with modified chitosan and polyvinyl alcohol solution in a first buffer solution.

[0009] The idea of ​​the present invention is as follows:

[0010] In the hydrogel network system of the present invention, multiple dynamic reversible chemical bonds are constructed, which are used as reversible connections and sacrificial bonds to dissipate stress, thereby enhancing the mechanical strength of the hydrogel of the present invention and giving it self-healing properties. Specifically: the present invention first uses a composite formed by blending chitosan modified with 3-carboxyphenylboronic acid and polyvinyl alcohol as a hydrogel matrix material to give the system sacrificial bonds to dissipate stress; secondly, the present invention uses polydopamine-modified MXene (MXene@PDA) as a conductive phase, and through the oxidative polymerization of dopamine, while forming a reversible Schiff base bond with the modified chitosan, more hydrogen bonds are also formed with polyvinyl alcohol (PVA) molecules, thereby constructing a three-dimensional network in which the polymer chain and the conductive phase are interconnected to obtain a hydrogel with multifunctional properties. The dynamic reversible bonds of the hydrogel of the present invention include boron ester bonds formed between chitosan modified with 3-carboxyphenylboronic acid and polyvinyl alcohol, Schiff base bonds formed between polydopamine and modified chitosan, and hydrogen bonds;

[0011] In addition, the present invention introduces polydopamine-modified two-dimensional nanomaterial MXene to construct hydrogel and apply it to flexible strain sensors. On the one hand, polydopamine with antioxidant effect is grafted onto MXene. Due to the oxidation of dopamine, the surface of MXene can obtain more quinone carbonyl groups, which form Schiff base bonds with the amino groups of modified chitosan in the gel system, which not only improves the strength of the gel network, but also enhances the dispersion uniformity of MXene in the gel network. On the other hand, dopamine rich in catechol groups can give the hydrogel better adhesion, so that it can be better attached to human skin, which is conducive to better collection and output of signals at the human-machine interface. In addition, the introduction of polydopamine-coated MXene (MXene@PDA) gives the hydrogel antibacterial and antioxidant properties, which can ensure the safety of the hydrogel and extend its service life.

[0012] According to the present invention, preferably, the method for preparing the hydrogel comprises: mixing polydopamine-modified MXene powder with a first buffer solution and uniformly dispersing by ultrasonication to obtain a first dispersion; mixing the first dispersion with modified chitosan to obtain a mixed solution; mixing the mixed solution with a polyvinyl alcohol solution, stirring and reacting to obtain the hydrogel.

[0013] According to the present invention, preferably, in the preparation of the hydrogel:

[0014] The concentration of the polydopamine-modified MXene powder in the first dispersion is 2-10 mg / mL;

[0015] The first buffer solution is a phosphate buffer solution with a pH value of 7.0-9.0;

[0016] The ultrasonic dispersion time is 5-20min;

[0017] The concentration of the modified chitosan in the mixed solution is 30-60 mg / mL;

[0018] The polyvinyl alcohol solution is a mixed solution of polyvinyl alcohol and a phosphate buffer solution with a pH of 7.0-9.0, and the concentration of the polyvinyl alcohol is 5-15wt%;

[0019] The mixing, stirring and reaction time is 15-40 minutes;

[0020] The volume ratio of the mixed liquid to the polyvinyl alcohol solution is 1:(1-3).

[0021] In the present invention, the self-healing hydrogel of the present invention has dynamic reversible boron ester bonds, Schiff base bonds and reversible hydrogen bonds between networks, wherein the dynamic boron ester bonds formed by the boric acid bonds of modified chitosan and the abundant ortho-hydroxyl groups of polyvinyl alcohol have a wider pH formation condition.

[0022] According to the present invention, preferably, the preparation method of the polydopamine-modified MXene powder (MXene@PDA) comprises: mixing the MXene powder with a second buffer solution and uniformly dispersing it by ultrasonication to obtain a second dispersion; mixing the second dispersion with dopamine hydrochloride, stirring and reacting, centrifuging and washing with water, and freeze-drying to obtain the polydopamine-modified MXene powder.

[0023] According to the present invention, preferably, in the preparation of the polydopamine-modified MXene powder:

[0024] The second buffer solution is a Tris buffer solution with a pH value of 7.0-9.0;

[0025] The mass ratio of the dopamine hydrochloride to the MXene powder is 1:(0.5-1.2);

[0026] The ultrasonic dispersion time is 5-20min;

[0027] The mixing, stirring and reaction time is 6-18 hours, and the temperature is 10-25°C.

[0028] In the present invention, dopamine hydrochloride is oxidized to polydopamine under alkaline conditions and coated on the surface of MXene through hydrogen bonding to obtain the MXene@PDA.

[0029] According to the present invention, preferably, the preparation method of the modified chitosan (chitosan grafted with 3-carboxyphenylboronic acid) comprises: mixing chitosan with an acetic acid aqueous solution to obtain a chitosan solution; mixing 3-carboxyphenylboronic acid, N-hydroxysuccinimide (NHS), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and methanol to obtain a phenylboric acid solution; mixing the chitosan solution with the phenylboric acid solution, stirring and reacting, dialyzing, and freeze-drying to obtain the modified chitosan.

[0030] According to the present invention, preferably, in the preparation of the modified chitosan:

[0031] The concentration of the acetic acid aqueous solution is 0.2-0.4wt%;

[0032] The amount ratio of chitosan, acetic acid aqueous solution, 3-carboxyphenylboric acid, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and methanol is (450-550):(55-65):(330-360):(230-260):(320-350):(35-45) g / L / g / g / g / L.

[0033] In the present invention, as a preferred embodiment, the molecular weight cutoff of the dialysis bag used for dialysis is 14000Da, and the dialysis time is three days.

[0034] According to the present invention, preferably, the hydrogel is a dynamic boron ester bond network self-healing conductive hydrogel, and the self-healing time is 2-7s.

[0035] According to the present invention, preferably, the hydrogel has a scavenging rate of 2,2-diphenyl-1-picrylhydrazyl free radical of ≥96%.

[0036] Another aspect of the present invention provides the use of the MXene functionalized antibacterial self-healing hydrogel in a flexible strain sensor.

[0037] The beneficial effects of the technical solution of the present invention are as follows: The present invention provides a tough, self-healing, highly adhesive, antibacterial functional conductive hydrogel that can be used in flexible strain sensors. It is worth mentioning that the present invention uses polydopamine-modified MXene (MXene@PDA) to not only enhance the antibacterial properties of the hydrogel material, but also improve the cross-linking degree of the gel network, improve its dispersion uniformity and antioxidant stability in the gel system, and obtain a self-healing conductive hydrogel with enhanced antioxidant and antibacterial properties. The preparation method of the hydrogel of the present invention is simple, and as an application in strain sensors, it can sensitively detect fine expressions and physiological signals. Specifically:

[0038] (1) The hydrogel of the present invention has excellent mechanical properties: The hydrogel of the present invention uses chitosan modified with 3-carboxyphenylboronic acid, polyvinyl alcohol and polydopamine modified MXene as raw materials, and uses polydopamine to build a bridge between the conductive filler and the chitosan / polyvinyl alcohol hydrogel matrix, which effectively improves the dispersion stability of the conductive filler MXene in the hydrogel matrix. At the same time, the flexible structure also reduces stress concentration to a certain extent and improves the mechanical stability of the material. And the boron ester bond, Schiff base bond, and hydrogen bond formed can act as a sacrificial unit under the action of external stress, dissipate mechanical energy, improve the strength and toughness of the material, and then enhance the maximum tensile strain at break of the hydrogel. The tensile strength of the hydrogel provided by the present invention can reach 39.2KPa, and the elongation at break can reach 916.15%.

[0039] (2) The hydrogel of the present invention has good self-healing and adhesion properties: the hydrogel network of the present invention contains boron ester bonds formed by chitosan modified with 3-carboxyphenylboronic acid and polyvinyl alcohol, Schiff base bonds formed by polydopamine and modified chitosan, and sufficient hydrogen bonding between polyvinyl alcohol molecules, so that the hydrogel can interact with multiple substrates and broken hydrogels, thereby exhibiting multi-substrate adhesion properties and rapid self-healing ability.

[0040] (3) The hydrogel of the present invention has excellent antibacterial properties: The hydrogel of the present invention uses modified chitosan and polyvinyl alcohol as the main gel matrix and polydopamine-modified MXene as the conductive filler. The antibacterial effect of the hydrogel of the present invention on Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli was evaluated by the exhibition board method. The experiment confirmed that the hydrogel exhibited excellent antibacterial effect.

[0041] (4) The hydrogel of the present invention has excellent sensing properties: The hydrogel of the present invention connects the conductive filler - polydopamine-modified MXene to the hydrogel network through the bridge effect of polydopamine, thereby improving the dispersion stability of MXene and giving the hydrogel excellent conductive properties. When applied to strain sensors, it can detect large-scale movements, fine micro-expressions, and physiological signals of various parts of the body (face, vocal cords, elbows, palms, knees, etc.), showing sensitive strain sensing response.

[0042] (5) The hydrogel of the present invention has good antioxidant properties: the hydrogel of the present invention can achieve a scavenging rate of 95.6% for 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals, showing strong antioxidant ability, and the enhanced chemical stability prolongs the service life of the flexible strain sensor.

[0043] (6) The preparation method of the hydrogel of the present invention is simple: the present invention uses chitosan grafted with 3-carboxyphenylboronic acid, dopamine hydrochloride, MXene and polyvinyl alcohol PVA as raw materials, and only needs simple mixing to obtain a conductive hydrogel with the advantages of self-healing, stretchability, antibacterial, antioxidant, adhesion and durability. The strain sensor prepared by the hydrogel can be used for large-scale human motion and physiological signal detection, and can monitor large-scale limb movements, fine micro-expressions and physiological signals in real time. It has high sensitivity and can be promoted and applied to human-machine interfaces, wearable and implantable sensor devices. The preparation method of the hydrogel of the present invention is simple, low-cost, and environmentally friendly, and has broad application prospects in the fields of wearable flexible devices, electronic skin, and medical care.

[0044] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0046] Figure 1 (a)-(b) shows the self-healing performance test of the hydrogel prepared in Example 1 of the present invention.

[0047] Figures 2(a)-(b) show the tensile performance test results of the hydrogels prepared in Examples 1-3 of the present invention and Comparative Example 1 (wherein Figure 2(b) from top to bottom are intuitive diagrams of the hydrogels prepared in Example 2 stretched to different lengths).

[0048] Figures 3(a)-(b) show the adhesion performance test of the hydrogel prepared in Example 3 of the present invention (Figure 3(a)-1 is glass, Figure 3(a)-2 is rubber, Figure 3(a)-3 is pig skin, Figure 3(a)-4 is metal, Figure 3(a)-5 is a wooden board, and Figure 3(a)-6 is a glass bottle).

[0049] Figure 4 The antibacterial performance test results of the hydrogels prepared in Example 2 of the present invention and Comparative Example 1 are shown. The negative control is an antibacterial performance graph without hydrogel.

[0050] Figure 5 The results of DPPH free radical scavenging experiments on the hydrogels prepared in Example 2 of the present invention and Comparative Example 1 are shown.

[0051] Figure 6 (a)-(b) shows the tensile sensing performance test of the hydrogel prepared in Example 2 of the present invention.

[0052] Figure 7The hydrogel prepared in Example 2 of the present invention is attached near the pulse of a volunteer's wrist to monitor the pulse in real time.

[0053] Figures 8(a)-(c) show the elbow bending sensing performance test of the hydrogel prepared in Example 2 of the present invention attached to the elbow (Figure 8(b) shows the normal bending speed of the elbow, and Figure 8(c) shows the rapid bending speed of the elbow). DETAILED DESCRIPTION

[0054] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0055] In the following embodiments:

[0056] The dopamine hydrochloride is from Beijing Yikainuo Technology Co., Ltd. (KYEK511);

[0057] The MXene powder was obtained from Shanghai MacLean Biochemical Technology Co., Ltd. (T992821).

[0058] Example 1

[0059] This embodiment provides a MXene functionalized antibacterial self-healing hydrogel, and the preparation method of the hydrogel includes:

[0060] S1: Preparation of polydopamine-modified MXene powder

[0061] The MXene powder was mixed with a 0.01 mol / L Tris buffer solution with a pH of 8.5 and ultrasonically dispersed to obtain a second dispersion; the second dispersion (10 mL, the concentration of MXene in the second dispersion was 2 mg / mL) was mixed with 40 mg of dopamine hydrochloride, stirred and reacted for 8 hours, washed with water by centrifugation until neutral, and freeze-dried to obtain the polydopamine-modified MXene powder (MXene@PDA).

[0062] S2: Preparation of modified chitosan

[0063] 500 mg of chitosan is mixed with 60 mL of 0.3 wt% acetic acid aqueous solution to obtain a chitosan solution; 343 mg of 3-carboxyphenylboric acid, 247 mg of N-hydroxysuccinimide (NHS), 333 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and 40 mL of methanol are mixed and stirred at 25° C. for 30 min to obtain a phenylboric acid solution; the chitosan solution and the phenylboric acid solution are mixed and stirred and reacted for 24 h, dialyzed (molecular weight cutoff 14000 Da) for three days, and freeze-dried to obtain the modified chitosan.

[0064] S3: Preparation of hydrogel

[0065] 8 mg of polydopamine-modified MXene powder (MXene@PDA) was mixed with 2 mL of a phosphate buffer solution with a pH of 7.4 and uniformly dispersed by ultrasonication to obtain a first dispersion; the first dispersion was mixed with 100 mg of modified chitosan to obtain a mixed solution; the mixed solution was mixed with 2 mL of a polyvinyl alcohol solution (the polyvinyl alcohol solution was a mixed solution of polyvinyl alcohol and a phosphate buffer solution with a pH of 8.5, prepared under 90° C. water bath conditions, and the concentration of polyvinyl alcohol was 10 wt %) and reacted for 20 min to obtain the hydrogel (BC-P-MP-8).

[0066] Example 2

[0067] This embodiment provides a MXene functionalized antibacterial self-healing hydrogel, and the preparation method of the hydrogel includes:

[0068] S1: Preparation of polydopamine-modified MXene powder

[0069] The MXene powder was mixed with a 0.01 mol / L Tris buffer solution with a pH of 9.0 and ultrasonically dispersed to obtain a second dispersion; the second dispersion (10 mL, the concentration of MXene in the second dispersion was 3 mg / mL) was mixed with 40 mg of dopamine hydrochloride, stirred and reacted for 6 hours, washed with water by centrifugation until neutral, and freeze-dried to obtain the polydopamine-modified MXene powder (MXene@PDA).

[0070] S2: The preparation of modified chitosan is the same as that in Example 1.

[0071] S3: Preparation of hydrogel

[0072] 12 mg of polydopamine-modified MXene powder (MXene@PDA) was mixed with 2 mL of a phosphate buffer solution at pH 7.4 and uniformly dispersed by ultrasonication to obtain a first dispersion; the first dispersion was mixed with 100 mg of modified chitosan to obtain a mixed solution; the mixed solution was mixed with 2 mL of a polyvinyl alcohol solution (the polyvinyl alcohol solution was a mixed solution of polyvinyl alcohol and a phosphate buffer solution at pH 7.4, prepared under 90°C water bath conditions, and the concentration of polyvinyl alcohol was 10 wt%) and reacted for 25 minutes to obtain the hydrogel (BC-P-MP-12).

[0073] Example 3

[0074] This embodiment provides a MXene functionalized antibacterial self-healing hydrogel, and the preparation method of the hydrogel includes:

[0075] S1: Preparation of polydopamine-modified MXene powder

[0076] The MXene powder was mixed with a 0.01 mol / L Tris buffer solution with a pH of 8.5 and ultrasonically dispersed to obtain a second dispersion; the second dispersion (10 mL, the concentration of MXene in the second dispersion was 4 mg / mL) was mixed with 40 mg of dopamine hydrochloride, stirred and reacted for 6 hours, washed with water by centrifugation until neutral, and freeze-dried to obtain the polydopamine-modified MXene powder (MXene@PDA).

[0077] S2: The preparation of modified chitosan is the same as that in Example 1.

[0078] S3: Preparation of hydrogel

[0079] 16 mg of polydopamine-modified MXene powder (MXene@PDA) was mixed with 2 mL of a phosphate buffer solution with a pH of 7.4 and uniformly dispersed by ultrasonication to obtain a first dispersion; the first dispersion was mixed with 100 mg of modified chitosan to obtain a mixed solution; the mixed solution was mixed with 2 mL of a polyvinyl alcohol solution (the polyvinyl alcohol solution was a mixed solution of polyvinyl alcohol and a phosphate buffer solution with a pH of 8.5, prepared under 90°C water bath conditions, and the concentration of polyvinyl alcohol was 10 wt%) and reacted for 20 minutes to obtain the hydrogel (BC-P-MP-16).

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a chitosan-polyvinyl alcohol (BC-P) hydrogel grafted with phenylboronic acid, and the preparation process is as follows:

[0082] Using 2 mL of pH 7.4 phosphate buffer as solvent, a 5 wt % 3-carboxyphenylboronic acid grafted chitosan solution (BC solution) was prepared;

[0083] A polyvinyl alcohol solution is prepared in a water bath at 90° C. (the polyvinyl alcohol solution is a mixed solution of polyvinyl alcohol and a phosphate buffer solution with a pH of 7.4, and the concentration of the polyvinyl alcohol is 10 wt %);

[0084] Take 2 mL of BC solution and 2 mL of PVA solution, mix the two solutions and stir them evenly to finally obtain BC-P hydrogel.

[0085] As shown in Figure 1, the self-healing performance test of the hydrogel prepared in Example 1 of the present invention is carried out. BC-P-MP hydrogel has excellent self-healing performance based on hydrogen bonds, boron ester bonds, Schiff base bonds and the interaction of multiple functional groups. As can be seen in Figure 1 (a), after the hydrogel is cut off and then re-contacted, its excellent rapid self-healing ability enables the hydrogel to heal quickly. Figure 1 (b) connects the hydrogel with an LED lamp and a power supply to form a series circuit. When the hydrogel is in a disconnected state, the small light bulb cannot be lit when the power is turned on. When the disconnected hydrogel is in contact, the hydrogel quickly heals and forms a conductive series circuit, so that the light bulb is successfully lit, indicating that the hydrogel has good self-healing properties.

[0086] As shown in Figure 2, the tensile properties of the hydrogels prepared in Examples 1-3 of the present invention and Comparative Example 1 were tested. The addition of MXene@PDA to the gel network can cause competitive binding in the hydrogel network, achieve more complex functional integration, and improve the mechanical strength of the hydrogel. As can be seen from Figure 2 (a), the introduction of MXene@PDA effectively improves the tensile properties of the hydrogel, and with the increase of the MXene@PDA content, the tensile strength and elongation at break of the hydrogel are effectively improved. When the dosage of MXene@PDA is 12 mg, the elongation at break of the hydrogel can reach a maximum of 916.15%, and the maximum stress reaches 39.2 KPa, which far exceeds the maximum tensile deformation that the skin can withstand (~80%).

[0087] As shown in Figure 3, the adhesion performance test of the self-healing hydrogel prepared in Example 3 of the present invention is carried out. The results of the intuitive adhesion experiment (Figure 3 (a)) show that the BC-P-MP organohydrogel has good adhesion performance to different substrates (pigskin, glass, rubber, metal and wood board) at room temperature. As shown in Figure 3 (b), the adhesion of the hydrogel prepared in Example 3 to pigskin, glass, rubber, metal and wood board is 3.82, 3.34, 1.74, 2.07 and 5.40 KPa respectively. The adhesion mechanism of the hydrogel to pigskin is mainly attributed to the formation of strong hydrogen bonds between the surface functional groups of the organohydrogel and the substrate. Not only that, the aldehyde group of the organohydrogel can also form a Schiff base bond with the amino group of the protein. For wood boards and rubber, the possible adhesion mechanism is attributed to the formation of abundant hydrogen bonds and electrostatic interactions between the hydrogel and the surface carboxyl groups of these substrates.

[0088] like Figure 4 As shown, the antibacterial performance test of the self-healing hydrogels prepared in Example 2 and Comparative Example 1 of the present invention is carried out. First, the BC-P gel prepared in Comparative Example 1 has certain antibacterial properties, which is due to the presence of chitosan giving it certain antibacterial properties. The number of Escherichia coli and Staphylococcus aureus in the BC-P-MP hydrogel group of Example 2 is reduced to a certain extent compared with the BC-P hydrogel group of Comparative Example 1. This is because MXene can cause bacterial death by destroying bacterial walls and bacterial membranes. Membrane destruction is the main antibacterial mechanism of MXene-based hydrogels that cause bacterial death. At the same time, the adhesion properties of PDA can recruit more bacteria to obtain better antibacterial properties.

[0089] like Figure 5 As shown, the DPPH radical scavenging experiment was conducted on the hydrogels prepared in Example 2 of the present invention and Comparative Example 1. First, the DPPH scavenging rate of MXene@PDA is higher than that of MXene, which indicates that the activity of scavenging DPPH may be attributed to the joint action of MXene and PDA, and the surface modification of MXene with PDA can enhance the antioxidant capacity of MXene. The introduction of MXene@PDA can increase the DPPH radical scavenging rate of the hydrogel from 50.9% to 95.6%. The improvement of antioxidant capacity increases the stability of the hydrogel and can extend the service life of the hydrogel strain sensor.

[0090] As shown in FIG6 , the self-healing hydrogel prepared in Example 2 of the present invention was tested for tensile sensing performance. As shown in FIG6 (a), when the BC-P-MP hydrogel is stretched to a certain tensile strain, the relative resistance change (ΔR / R0) increases with the increase of strain. When the strain remains unchanged, ΔR / R0 maintains a constant value, indicating that the BC-P-MP hydrogel has good electrical stability. As shown in FIG6 (b), within the tensile range of 0-200%, the strain factor GF calculated by the rate of change of ΔR / R0 to strain is 0.95 (0-100% strain), 1.34 (100-150% strain) and 1.73 (150%-200% strain), respectively, with good sensitivity. The applicant attributes the resistance change during the deformation of the BC-P-MP hydrogel to the rearrangement of the 3D conductive MXene@PDA network for electron transport and the change of the 3D interconnected porous structure of the hydrogel for ion migration. Under stretching, the slippage of MXene@PDA nanosheets leads to a longer electron transport path, and the reduction of the pore size of the hydrogel network leads to a shorter ion migration path. Therefore, the resistance of the BC-P-MP hydrogel increases in time when undergoing tensile deformation.

[0091] like Figure 7 As shown, the self-healing hydrogel prepared in Example 2 of the present invention is attached near the wrist pulse of a volunteer to monitor the pulse in real time. Figure 7 As shown, the normal and regular pulse waveform of the volunteer is displayed, and the pulse rate is about 72 beats per minute (bpm). The high-sensitivity sensing performance of BC-P-MP hydrogel enables it to accurately monitor the pulse and obtain detailed pulse waveforms, including the systolic peak (P1) and the diastolic peak (P2). At the same time, Δh / Δt can indirectly reflect the myocardial contractility index. The volunteer's pulse waveform rises quickly and has an obvious second peak, and the second peak is relatively late, indicating that the volunteer's heart has a strong ejection capacity, low vascular resistance, good vascular elasticity, and sufficient blood supply.

[0092] As shown in Figure 8, the self-healing hydrogel prepared in Example 2 of the present invention was attached to the elbow to test the elbow bending sensing performance. When the BC-P-MP hydrogel was attached to the elbow of a volunteer to simulate normal elbow bending and rapid elbow bending, the signal peak shape at the normal bending rate was similar to the signal peak shape at the rapid bending rate within the same time, but the frequency was significantly lower, indicating that the BC-P-MP hydrogel can judge different motion states of the human body by collecting the frequency of the signal.

[0093] From the above, it can be seen that the hydrogel prepared by the present invention has good self-healing, stretchability, adhesion, antibacterial and antioxidant properties; it has high sensitivity and can realize real-time monitoring of large-scale human movements, fine micro-expressions and physiological signals, and can be applied to medical testing, human-machine interfaces, and wearable flexible devices.

[0094] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A MXene functionalized antibacterial self-healing hydrogel, characterized in that: The hydrogel is obtained by mixing and reacting polydopamine-modified MXene powder with modified chitosan and polyvinyl alcohol solution in a first buffer solution.

2. The MXene functionalized antibacterial self-healing hydrogel according to claim 1, wherein: The preparation method of the hydrogel comprises: mixing polydopamine-modified MXene powder with a first buffer solution and uniformly dispersing the mixture by ultrasonication to obtain a first dispersion; mixing the first dispersion with modified chitosan to obtain a mixed solution; and mixing the mixed solution with a polyvinyl alcohol solution, stirring the mixture and reacting the mixture to obtain the hydrogel.

3. The MXene functionalized antibacterial self-healing hydrogel according to claim 2, wherein: The concentration of the polydopamine-modified MXene powder in the first dispersion is 2-10 mg / mL; The first buffer solution is a phosphate buffer solution with a pH value of 7.0-9.0; The ultrasonic dispersion time is 5-20min; The concentration of the modified chitosan in the mixed solution is 30-60 mg / mL; The polyvinyl alcohol solution is a mixed solution of polyvinyl alcohol and a phosphate buffer solution with a pH of 7.0-9.0, and the concentration of the polyvinyl alcohol is 5-15wt%; The mixing, stirring and reaction time is 15-40 minutes; The volume ratio of the mixed liquid to the polyvinyl alcohol solution is 1:(1-3).

4. The MXene functionalized antibacterial self-healing hydrogel according to claim 1, wherein: The preparation method of the polydopamine-modified MXene powder comprises: mixing the MXene powder with a second buffer solution and uniformly dispersing it by ultrasonication to obtain a second dispersion; mixing the second dispersion with dopamine hydrochloride, stirring and reacting, centrifugally washing with water, and freeze-drying to obtain the polydopamine-modified MXene powder.

5. The MXene functionalized antibacterial self-healing hydrogel according to claim 4, wherein: The second buffer solution is a Tris buffer solution with a pH value of 7.0-9.0; The mass ratio of the dopamine hydrochloride to the MXene powder is 1:(0.5-1.2); The ultrasonic dispersion time is 5-20min; The mixing, stirring and reaction time is 6-18 hours, and the temperature is 10-25°C.

6. The MXene functionalized antibacterial self-healing hydrogel according to claim 1, wherein: The preparation method of the modified chitosan comprises: mixing chitosan with an acetic acid aqueous solution to obtain a chitosan solution; mixing and stirring 3-carboxyphenylboric acid, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and methanol to obtain a phenylboric acid solution; mixing and stirring the chitosan solution and the phenylboric acid solution, reacting, dialysis, and freeze-drying to obtain the modified chitosan.

7. The MXene functionalized antibacterial self-healing hydrogel according to claim 6, wherein: The concentration of the acetic acid aqueous solution is 0.2-0.4wt%; The amount ratio of chitosan, acetic acid aqueous solution, 3-carboxyphenylboric acid, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and methanol is (450-550):(55-65):(330-360):(230-260):(320-350):(35-45) g / L / g / g / g / L.

8. The MXene functionalized antibacterial self-healing hydrogel according to claim 1, wherein: The self-healing time of the hydrogel is 2-7s.

9. The MXene functionalized antibacterial self-healing hydrogel according to claim 1, wherein: The hydrogel has a scavenging rate of 96% or more for 2,2-diphenyl-1-picrylhydrazyl free radicals.

10. Application of the MXene functionalized antibacterial self-healing hydrogel according to any one of claims 1 to 9 in a flexible strain sensor.

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