MXene functionalized antibacterial self-healing hydrogel and application thereof

Abstract

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

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials technology, and more specifically, relates to an MXene-functionalized antibacterial self-healing hydrogel and its applications. Background Technology

[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 and health monitoring have developed rapidly. Among them, flexible strain sensors, due to their dual characteristics of flexibility and conductivity, can exhibit resistance or capacitance signals in response to external stress or external stimuli, thereby monitoring human movement or physiological signals, and are widely used in the field of medical and health monitoring.

[0003] Compared to traditional rigid sensors, flexible strain sensors exhibit significant advantages in tensile strength and adhesion to external materials, showing great potential in wearable devices, artificial intelligence, and electronic skin. Flexible strain sensors typically incorporate conductive fillers (graphene, carbon nanotubes, metal nanoparticles) into an elastic gel matrix. However, the uniform distribution of these conductive fillers is often difficult, affecting their mechanical properties and detection sensitivity. Furthermore, damage to the flexible hydrogel matrix can damage or even disable the sensor, impacting data acquisition and subsequent analysis. This is particularly problematic in implantable medical devices, where surgical replacement may be necessary.

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

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

[0006] In summary, optimizing the hydrogel network structure, constructing composite hydrogels, improving their basic properties, and endowing them with multifunctional properties are essential for enhancing the practical value of flexible strain sensors and broadening their application fields. Therefore, there is an urgent need to propose an MXene-functionalized antibacterial self-healing hydrogel. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing an MXene-functionalized antibacterial self-healing hydrogel and its applications. This invention yields a dynamic network self-healing conductive hydrogel based on dynamic borosilicate bonds, Schiff base bonds, and non-covalent interactions, which can be applied in flexible strain sensors.

[0008] To achieve the above objectives, the present invention provides an MXene-functionalized antibacterial self-healing hydrogel, 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 concept of this invention is as follows:

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

[0011] Furthermore, this invention introduces polydopamine-modified two-dimensional nanomaterial MXene to construct hydrogels and apply them to flexible strain sensors. On one hand, by grafting antioxidant polydopamine onto MXene, the oxidation of dopamine allows MXene to acquire more quinone carbonyl groups, forming Schiff base bonds with the amino groups of modified chitosan in the gel system. This not only improves the strength of the gel network but also enhances the uniformity of MXene dispersion within the network. On the other hand, dopamine rich in catechol groups imparts good adhesion to the hydrogel, allowing it to better adhere to human skin and facilitating better signal collection and output at the human-machine interface. Moreover, the introduction of polydopamine-coated MXene (MXene@PDA) endows the hydrogel with antibacterial and antioxidant properties, ensuring its safety and extending its service life.

[0012] According to the present invention, preferably, the method for preparing the hydrogel includes: mixing polydopamine-modified MXene powder with a first buffer solution and ultrasonically dispersing it uniformly to obtain a first dispersion; mixing the first dispersion with modified chitosan to obtain a mixture; and mixing and stirring the mixture with a polyvinyl alcohol solution to react and 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 of 7.0-9.0;

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

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

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

[0019] The mixing and reaction time is 15-40 minutes.

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

[0021] In this invention, the self-healing hydrogel has dynamic and reversible boron ester bonds, Schiff base bonds, and reversible hydrogen bonds between networks. 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 wide range of pH conditions.

[0022] According to the present invention, preferably, the preparation method of the polydopamine-modified MXene powder (MXene@PDA) includes: mixing MXene powder with a second buffer solution and ultrasonically dispersing it uniformly to obtain a second dispersion; mixing and stirring the second dispersion with dopamine hydrochloride and reacting it, 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 of 7.0-9.0;

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

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

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

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

[0029] According to the present invention, preferably, the preparation method of the modified chitosan (3-carboxyphenylboronic acid-grafted chitosan) includes: mixing chitosan with an aqueous acetic acid solution to obtain a chitosan solution; mixing and stirring 3-carboxyphenylboronic acid, N-hydroxysuccinimide (NHS), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) with methanol to obtain a phenylboronic acid solution; mixing and stirring the chitosan solution with the phenylboronic acid solution and reacting, dialyzing, and lyophilizing 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 0.2-0.4 wt%.

[0032] The ratio of chitosan, aqueous acetic acid, 3-carboxyphenylboronic 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.

[0033] In this invention, as a preferred embodiment, the dialysis bag used for dialysis has a molecular weight cutoff of 14,000 Da, 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 with a self-healing time of 2-7 seconds.

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

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

[0037] The beneficial effects of the technical solution of this invention are as follows: This invention provides a tough, self-healing, highly adhesive, and antibacterial functionalized conductive hydrogel that can be applied in flexible strain sensors. It is worth mentioning that the polydopamine-modified MXene (MXene@PDA) used in this invention not only enhances the antibacterial properties of the hydrogel material but also increases the cross-linking degree of the gel network, improving its dispersion uniformity and antioxidant stability in the gel system, thus obtaining a self-healing conductive hydrogel with enhanced antioxidant and antibacterial properties. The hydrogel preparation method of this invention is simple, and when applied to strain sensors, it can sensitively detect subtle facial expressions and physiological signals. Specifically:

[0038] (1) The hydrogel of this invention possesses excellent mechanical properties: The hydrogel of this invention uses 3-carboxyphenylboronic acid-modified chitosan, polyvinyl alcohol, and polydopamine-modified MXene as raw materials. Polydopamine forms a bridge between the conductive filler and the chitosan / polyvinyl alcohol hydrogel matrix, effectively improving the dispersion stability of the conductive filler MXene in the hydrogel matrix. Simultaneously, the flexible structure reduces stress concentration to some extent, improving the mechanical stability of the material. Furthermore, the formed boronic ester bonds, Schiff base bonds, and hydrogen bonds can act as sacrificial units under external stress, dissipating mechanical energy and improving the strength and toughness of the material, thereby enhancing the maximum tensile strain at break of the hydrogel. The hydrogel provided by this invention has a tensile strength of up to 39.2 kPa and an elongation at break of 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, which enables the hydrogel to interact with multiple substrates and fractured 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 against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli was evaluated by the plate method. The experiment confirmed that the hydrogel exhibits excellent antibacterial effect.

[0041] (4) The hydrogel of the present invention has excellent sensing performance: The hydrogel of the present invention connects the conductive filler - polydopamine modified MXene to the hydrogel network through the bridging effect of polydopamine, thereby improving the dispersion stability of MXene and giving the hydrogel superior conductivity. When applied to strain sensors, it can detect large-amplitude movements, fine micro-expressions and physiological signals of various parts of the body (face, vocal cords, elbows, palms, knees, etc.), and exhibits 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-picrylhydrazine (DPPH) free radicals. It exhibits strong antioxidant capacity, and the enhanced chemical stability improves the service life of the flexible strain sensor.

[0043] (6) The hydrogel preparation method of this invention is simple: This invention uses chitosan grafted with 3-carboxyphenylboronic acid, dopamine hydrochloride, MXene, and polyvinyl alcohol (PVA) as raw materials. A conductive hydrogel with advantages such as self-healing, stretchability, antibacterial properties, antioxidant properties, adhesion, and durability can be obtained simply by mixing these materials. The strain sensor prepared from this hydrogel can be used for detecting large-amplitude human movements and physiological signals. It can monitor large-amplitude limb movements, subtle micro-expressions, and physiological signals in real time, exhibiting high sensitivity. It can be widely applied to human-machine interfaces, wearable devices, and implantable sensing devices. The hydrogel preparation method of this invention is simple, low-cost, and environmentally friendly, and has broad application prospects in wearable flexible devices, electronic skin, and healthcare.

[0044] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

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

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

[0047] Figures 2(a)-(b) show the tensile properties of the hydrogels prepared in Examples 1-3 and Comparative Example 1 of the present invention (wherein, Figure 2(b) is a visual diagram of the hydrogels prepared in Example 2 stretched to different lengths from top to bottom).

[0048] Figures 3(a)-(b) show the adhesion performance test results 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 pigskin, Figure 3(a)-4 is metal, Figure 3(a)-5 is wood, and Figure 3(a)-6 is glass bottle).

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

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

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

[0052] Figure 7The image shows a hydrogel prepared in Example 2 of the present invention attached to the wrist near the pulse of a volunteer for real-time monitoring of pulse.

[0053] Figures 8(a)-(c) show the elbow flexion sensing performance test results when the hydrogel prepared in Example 2 of the present invention is attached to the elbow (Figure 8(b) shows the normal elbow flexion speed, and Figure 8(c) shows the rapid elbow flexion speed). Detailed Implementation

[0054] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0055] In the following embodiments:

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

[0057] The MXene powder is from Shanghai McLean Biochemical Technology Co., Ltd. (T992821).

[0058] Example 1

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

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

[0061] MXene powder was mixed with a 0.01 mol / L Tris buffer solution at pH 8.5 and ultrasonically dispersed to obtain a second dispersion. The second dispersion (10 mL, with MXene concentration of 2 mg / mL) was mixed with 40 mg dopamine hydrochloride and stirred for 8 h. After centrifugation and washing with water until neutral, the mixture was lyophilized to obtain the polydopamine-modified MXene powder (MXene@PDA).

[0062] S2: Preparation of modified chitosan

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

[0064] S3: Preparation of hydrogels

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

[0066] Example 2

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

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

[0069] MXene powder was mixed with a 0.01 mol / L Tris buffer solution at pH 9.0 and ultrasonically dispersed to obtain a second dispersion. The second dispersion (10 mL, with MXene concentration of 3 mg / mL) was mixed with 40 mg dopamine hydrochloride and stirred for 6 h. After centrifugation and washing with water until neutral, the mixture was lyophilized to obtain the polydopamine-modified MXene powder (MXene@PDA).

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

[0071] S3: Preparation of hydrogels

[0072] 12 mg of polydopamine-modified MXene powder (MXene@PDA) was mixed with 2 mL of phosphate buffer solution at pH 7.4 and ultrasonically dispersed 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 then mixed with 2 mL of polyvinyl alcohol solution (the polyvinyl alcohol solution was a mixture of polyvinyl alcohol and phosphate buffer solution at pH 7.4, prepared under a 90°C water bath, with a polyvinyl alcohol concentration of 10 wt%) and stirred for 25 min to obtain the hydrogel (BC-P-MP-12).

[0073] Example 3

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

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

[0076] MXene powder was mixed with a 0.01 mol / L Tris buffer solution at pH 8.5 and ultrasonically dispersed to obtain a second dispersion. The second dispersion (10 mL, with MXene concentration of 4 mg / mL) was mixed with 40 mg dopamine hydrochloride and stirred for 6 h. After centrifugation and washing with water until neutral, the mixture was lyophilized to obtain the polydopamine-modified MXene powder (MXene@PDA).

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

[0078] S3: Preparation of hydrogels

[0079] 16 mg of polydopamine-modified MXene powder (MXene@PDA) was mixed with 2 mL of phosphate buffer solution at pH 7.4 and ultrasonically dispersed 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 then mixed with 2 mL of polyvinyl alcohol solution (the polyvinyl alcohol solution was a mixture of polyvinyl alcohol and phosphate buffer solution at pH 8.5, prepared under a 90°C water bath, with a polyvinyl alcohol concentration of 10 wt%) and stirred for 20 min to obtain the hydrogel (BC-P-MP-16).

[0080] Comparative Example 1

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

[0082] A 5 wt% solution of 3-carboxyphenylboronic acid-grafted chitosan (BC solution) was prepared using 2 mL of phosphate buffer solution at pH 7.4 as the solvent.

[0083] A polyvinyl alcohol solution was prepared under a 90℃ water bath (the polyvinyl alcohol solution was a mixed solution of polyvinyl alcohol and a phosphate buffer solution with a pH of 7.4, and the concentration of polyvinyl alcohol was 10wt%).

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

[0085] Figure 1 shows the self-healing performance test of the hydrogel prepared in Example 1 of this invention. The BC-P-MP hydrogel exhibits excellent self-healing properties based on hydrogen bonds, boronic ester bonds, Schiff base bonds, and the interaction of various functional groups. As shown in Figure 1(a), when the hydrogel is cut and then re-contacted, its excellent rapid self-healing ability allows it to heal quickly. Figure 1(b) shows a series circuit formed by the hydrogel, an LED light, and a power supply. When the hydrogel is disconnected, the light bulb cannot be lit when the power is on. However, when the disconnected hydrogel is re-contacted, it heals rapidly and forms a conductive series circuit, successfully lighting the bulb. This demonstrates the excellent self-healing properties of the hydrogel.

[0086] Figure 2 shows the tensile properties of the hydrogels prepared in Examples 1-3 and Comparative Example 1 of this invention. The addition of MXene@PDA to the gel network can induce competitive bonding within the hydrogel network, enabling more complex functional integration and improving the mechanical strength of the hydrogel. As shown in Figure 2(a), the introduction of MXene@PDA effectively improves the tensile properties of the hydrogel. Furthermore, with the increase of MXene@PDA content, both the tensile strength and elongation at break of the hydrogel are effectively increased. When the amount of MXene@PDA is 12 mg, the maximum elongation at break of the hydrogel reaches 916.15%, and the maximum stress reaches 39.2 kPa, far exceeding the maximum tensile deformation (~80%) that the skin can withstand.

[0087] Figure 3 shows the adhesion performance test results of the self-healing hydrogel prepared in Example 3 of this invention. The results of the direct adhesion experiment (Figure 3(a)) indicate that the BC-P-MP organic hydrogel exhibits good adhesion performance to different substrates (pigskin, glass, rubber, metal, and wood) at room temperature. Figure 3(b) shows that the adhesion forces of the hydrogel prepared in Example 3 to pigskin, glass, rubber, metal, and wood are 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 organic hydrogel and the substrate. Furthermore, the aldehyde groups of the organic hydrogel can also form Schiff base bonds with the amino groups of proteins. For wood and rubber, the possible adhesion mechanism is attributed to the abundant hydrogen bonds and electrostatic interactions between the surface carboxyl groups of the hydrogel and these substrates.

[0088] like Figure 4 The image shows the antibacterial performance test results of the self-healing hydrogels prepared in Example 2 and Comparative Example 1 of this invention. Firstly, the BC-P gel prepared in Comparative Example 1 exhibits certain antibacterial properties, which is attributed to the presence of chitosan. Compared to the BC-P hydrogel group in Comparative Example 1, the BC-P-MP hydrogel group in Example 2 showed a reduction in the number of Escherichia coli and Staphylococcus aureus. This is because MXene can cause bacterial death by disrupting the bacterial wall and membrane. Membrane disruption is the main antibacterial mechanism by which MXene-based hydrogels cause bacterial death. Simultaneously, the adhesive properties of PDA can recruit more bacteria, resulting in better antibacterial performance.

[0089] like Figure 5 The diagram shows the DPPH radical scavenging experiment conducted on the hydrogels prepared in Example 2 and Comparative Example 1 of this invention. Firstly, the DPPH scavenging rate of MXene@PDA is higher than that of MXene, indicating that the DPPH scavenging activity may be attributed to the combined effect of MXene and PDA, and that modifying the MXene surface 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 improved antioxidant capacity increases the stability of the hydrogel, which can extend the service life of the hydrogel strain sensor.

[0090] Figure 6 shows the tensile sensing performance test of the self-healing hydrogel prepared in Example 2 of this invention. As shown in Figure 6(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 constant, ΔR / R0 remains constant, indicating that the BC-P-MP hydrogel has good electrical stability. As shown in Figure 6(b), in the tensile range of 0-200%, the strain coefficients GF calculated from the rate of change of strain of ΔR / R0 are 0.95 (0-100% strain), 1.34 (100-150% strain), and 1.73 (150%-200% strain), respectively, showing good sensitivity. The applicant attributes the resistance change during the deformation process 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 an increase in the electron transport path, while the reduction in the pore size of the hydrogel network leads to a decrease in the ion migration path. Therefore, the electrical resistance of the BC-P-MP hydrogel increases promptly upon undergoing tensile deformation.

[0091] like Figure 7 As shown, the self-healing hydrogel prepared in Example 2 of this invention is attached to the wrist pulse area of ​​a volunteer for real-time monitoring of pulse rate. Figure 7 As shown, the volunteer's normal and regular pulse waveform is displayed, with a pulse rate of approximately 72 beats per minute (bpm). The high-sensitivity sensing performance of the BC-P-MP hydrogel enables accurate monitoring of the pulse, obtaining detailed pulse waveforms, including the systolic peak (P1) and diastolic peak (P2). Simultaneously, Δh / Δt can indirectly reflect myocardial contractility indicators. The volunteer's pulse waveform shows a rapid rise with a distinct second peak, which is relatively late in the pulse, indicating strong cardiac ejection capacity, low vascular resistance, good vascular elasticity, and adequate blood supply.

[0092] As shown in Figure 8, the self-healing hydrogel prepared in Example 2 of this invention was applied to the elbow for elbow flexion sensing performance testing. When the BC-P-MP hydrogel was applied to a volunteer's elbow to simulate normal elbow flexion and rapid elbow flexion, the signal peak shape at the normal flexion rate was similar to that at the rapid flexion rate, but the frequency was significantly lower. This indicates that the BC-P-MP hydrogel can determine different movement states of the human body by collecting signal frequencies.

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

[0094] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An 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; The method for preparing the modified chitosan includes: mixing chitosan with an aqueous acetic acid solution to obtain a chitosan solution; mixing and stirring 3-carboxyphenylboronic acid, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride with methanol to obtain a phenylboronic acid solution; mixing and stirring the chitosan solution with the phenylboronic acid solution and reacting, dialyzing, and lyophilizing to obtain the modified chitosan.

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

4. The MXene-functionalized antibacterial self-healing hydrogel according to claim 1, wherein, The method for preparing the polydopamine-modified MXene powder includes: mixing MXene powder with a second buffer solution and ultrasonically dispersing it uniformly to obtain a second dispersion; mixing and stirring the second dispersion with dopamine hydrochloride and reacting it, centrifuging and 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 of 7.0-9.0; The mass ratio of dopamine hydrochloride to MXene powder is 1:(0.5-1.2). The ultrasonic dispersion time is 5-20 minutes; The mixing and reaction time is 6-18 hours, and the temperature is 10-25℃.

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

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

8. The MXene-functionalized antibacterial self-healing hydrogel according to claim 1, wherein, The hydrogel exhibits a scavenging rate of ≥96% for 2,2-diphenyl-1-picrylhydrazine free radicals.

9. The application of the MXene-functionalized antibacterial self-healing hydrogel according to any one of claims 1-8 in the preparation of flexible strain sensors.

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