Composite hydrogel material and preparation method and its application in wearable sensors

Abstract

The present invention discloses a preparation method of a polypeptide composite hydrogel material with anti-pollution and self-healing properties and its application in wearable electrochemical sensors. The polypeptide composite hydrogel material comprises: L-type polypeptide powder and reduced graphene oxide; the L-type polypeptide powder is dissolved in a DMSO solvent to prepare a polypeptide solution, and then the polypeptide solution is diluted with an aqueous solution of reduced graphene oxide, and the composite hydrogel material is obtained. The wearable electrochemical sensor is a flexible electrochemical sensor based on the polypeptide composite hydrogel, which is modified onto a flexible printed electrode interface by a drop coating method. The sensor of the present invention does not need to process sweat, and can directly measure the biochemical indicators therein, and can be free from contamination and influence in sweat with complex components and usually small collection volume; the polypeptide composite hydrogel of the present invention has good biocompatibility, high sensitivity, good flexibility and self-healing function.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and more particularly to a composite hydrogel material, a preparation method thereof, and a wearable sensor. Background Art

[0002] In recent years, wearable sensors have attracted much attention due to their great potential in vital sign monitoring. Their use is limited by the energy consumption provided by small batteries, which limits the autonomy of the device. Therefore, it is crucial to develop sustainable energy management and build self-powered sensors in the next generation of wearable electrochemical devices (WeSPEDs). Self-powered sensors do not require power, are easy to miniaturize, and have the potential to build wearable, portable, and real-time detection devices. Unlike traditional electrochemical sensors, fuel cell (FC)-based wearable electrochemical devices do not require external power supplies and complex equipment, but are power generation devices that convert the chemical energy of redox reactions in fuel cells into electrical energy. Autonomous energy systems are key to continuously powering electronic skin. Potential autonomous energy sources include sunlight, human motion, sweat, and body heat, among which biofuels in human sweat are the most natural and feasible candidate energy sources. By using biofuels in human sweat, wearable biofuel cells can be made into reliable skin power sources. Not only does human sweat provide the natural fuel needed for self-powered sensors, but wearable sensors applied to human skin sweat can also provide the content of human biochemical metabolic markers. Therefore, continuous monitoring of biomarkers in sweat has the potential to complement laboratory-based blood analysis results, making real-time monitoring of daily health status and early disease detection and management possible.

[0003] However, although great progress has been made in the research of flexible wearable sweat sensors at home and abroad in recent years, there is still a gap from practical application. At present, such wearable sensors have not been commercialized and marketed. The main reasons are as follows:

[0004] (1) One of the key challenges in sweat analysis: the lack of self-healing flexible polypeptide hydrogel materials

[0005] Most of the current wearable sensors are rigid. When people move, rigid sensors may temporarily detach from the soft body surface, resulting in inaccurate data recording. If the accuracy of biometric information cannot be guaranteed, the data obtained cannot be used to judge health status. Therefore, data accuracy is a prerequisite for wearable biodiagnostics. Hydrogels are considered to have great application prospects in skin sweat due to their high water content, high permeability and flexibility, and their ability to simulate the function of extracellular matrix. However, hydrogel flexible materials are prone to structural damage or breakage due to physical activities such as skin bending and wrinkling, thereby affecting the output of sensor information.

[0006] (2) The second key challenge of sweat analysis: lack of anti-fouling hydrogels for detection in complex environments

[0007] Ideally, the analysis of sweat by flexible wearable sensor devices should be unprocessed, and the biochemical indicators in sweat can be directly measured, which can be free from contamination and influence in sweat with complex composition and usually small collection volume. Human body fluids are similar to blood, with very complex composition. A large number of coexisting chemical species, such as skin debris, protein and a large amount of human body oil, can be adsorbed to the sensing interface to contaminate and passivate the electrode, resulting in reduced credibility of the detection results. Therefore, it is urgent to develop anti-pollution hydrogel flexible materials with good anti-pollution ability.

[0008] In summary, the existing technical solutions have the following defects:

[0009] 1) Before the existing electrochemical sensor is tested, the test sample needs to be pre-treated to remove most of the substances that will contaminate the electrode, and then the test is carried out.

[0010] 2) Existing conductive materials with active functions modified at the electrode interface (such as metal nanowires, metal nanoparticles, graphene, carbon nanotubes, etc.) have inherent disadvantages such as high rigidity, easy pollution, and short fatigue life. It is difficult for them to better fit human skin and withstand the complex mechanical shapes of natural skin such as twisting, bending, stretching and folding, and it is difficult to achieve the self-healing function of the material, which brings great challenges to the real practical application of wearable electronic devices.

[0011] 3) There is currently a lack of wearable self-powered fuel cells that can directly provide the most natural autonomous energy. Without the need for external energy, they can use the biological raw materials in human sweat to provide energy and detect changes in biochemical information in human sweat.

[0012] Therefore, how to obtain a flexible, self-healing material that fits well with human skin, develop personalized medical and monitoring equipment that is non-destructive to the skin, enable clinical testing to be free from the limitations of large equipment in laboratories or hospitals, and be used to continuously, in situ, and intuitively detect a series of clinically effective chemical and biological molecular information on patients is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0013] In view of this, the present invention provides a method for preparing a composite hydrogel material and its application in a self-powered wearable sensor. The present invention provides an anti-pollution-self-healing polypeptide composite hydrogel material with high flexibility, self-healing performance, high sensitivity and comprehensive anti-pollution performance, and constructs a micro self-powered wearable electrochemical sweat sensor based on the multifunctional material for detecting target objects in sweat. Finally, through a small Bluetooth transmission system, the biochemical sensing signal in the sweat is transmitted to the mobile phone interface via Bluetooth for detection.

[0014] In order to achieve the above object, the present invention adopts the following technical solution:

[0015] A composite hydrogel material comprises: L-type polypeptide powder and reduced graphene oxide.

[0016] Preferably, the L-type polypeptide powder is (Nap) 2 kkf;

[0017] In the above formula (Nap) 2 express k represents lysine; f represents phenylalanine.

[0018] The two naphthalene groups have hydrophobic force and are connected together with reduced graphene oxide through π-π stacking. This physical force will not disappear and is the basis for the self-healing of the composite hydrogel.

[0019] Another object of the present invention is to provide a method for preparing the above-mentioned composite hydrogel material, comprising: dissolving L-type polypeptide powder in DMSO solvent to prepare a polypeptide solution, then diluting the polypeptide solution with a reduced graphene oxide (rGOx) aqueous solution, and standing to obtain an rGOx / Pep composite hydrogel.

[0020] Preferably, the concentration of the polypeptide solution is 150 mg / mL, the concentration of the reduced graphene oxide aqueous solution is 2 mg / mL, and the dilution is performed to dilute the polypeptide solution to a concentration of 5 mg / mL.

[0021] At the above concentration, the obtained polypeptide composite hydrogel has the best flexibility and self-healing properties.

[0022] Preferably, the standing time is 0.5 h.

[0023] Another object of the present invention is to provide a self-powered wearable electrochemical sensor, by which 10 μL of the above-mentioned composite hydrogel is modified onto the flexible printed electrode interface by a drop coating method to construct a flexible electrochemical sensor based on the composite hydrogel.

[0024] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The sensor of the present invention does not require any treatment of sweat and can directly measure the biochemical indicators therein, and can be protected from contamination and influence in sweat with complex components and usually small collection volume;

[0026] (2) The composite hydrogel of the present invention has good biocompatibility, high sensitivity, good flexibility and self-healing function;

[0027] (3) The wearable sensor of the present invention utilizes biological materials in human sweat to provide energy and detect changes in biochemical information in human sweat without requiring external energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 A schematic diagram of a wearable sensor provided by the present invention;

[0030] Figure 2 A schematic diagram of the working principle of the wearable sensor provided by the present invention;

[0031] Figure 3 The anti-pollution principle diagram (A) and self-healing performance diagram (B) of the composite hydrogel material;

[0032] Figure 4 This is a physical picture of the wearable sensor of the present invention;

[0033] Figure 5 Figure 2 is a diagram of the self-healing process of the composite hydrogel;

[0034] Figure 6 E of different contents of uric acid (UA) OCV Signal response diagram;

[0035] Figure 7 DPV diagrams of the anti-contamination of bare electrode (A) and hydrogel (B) to sweat. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] Materials and Reagents:

[0039] The designed peptide is (Nap) 2 kkf (peptide is L polypeptide), reduced graphene oxide (rGOx), pure protein myoglobin (Mb), lysozyme (Lys), bovine serum albumin (BSA).

[0040] Material preparation process:

[0041] 1. Synthesis of polypeptide hydrogel materials: The synthesized L-type polypeptide powders were dissolved in DMSO solvent to prepare stock solutions with a concentration of 150 mg / mL; the polypeptide solutions were then diluted with ultrapure water to a polypeptide concentration of 5 mg / mL, and allowed to stand for 0.5 h to form gels, thereby obtaining polypeptide hydrogels.

[0042] 2. Synthesis of polypeptide composite hydrogel material: The synthesized L-type polypeptide powder was dissolved in DMSO solvent to prepare a stock solution with a concentration of 150 mg / mL; the polypeptide solution was then diluted with rGOx aqueous solution (2 mg / mL) to a polypeptide concentration of 5 mg / mL. After standing for 0.5 h, it formed a gel to obtain rGOx / Pep hydrogel.

[0043] Construction and testing process of electrochemical sensor:

[0044] 1. Electrode construction process: 10 mL of polypeptide composite hydrogel was modified onto the flexible printed electrode interface by drop coating to construct a flexible electrochemical sensor based on the composite hydrogel.

[0045] 2. Evaluation of antifouling performance: The antifouling performance of different modified electrode surfaces was evaluated in a pure protein environment using BSA, Lys, and Mb proteins with different charges (negatively charged, positively charged, and neutrally charged, respectively). In addition, the antifouling performance of the sensor was tested in a complex environment (human sweat), and the differential pulse voltammetry (DPV) signal change rate was recorded before and after 0.5h of immersion in samples of different concentrations of protein and human sweat to evaluate the short-term antifouling performance.

[0046] Sensing test: The catalytic performance and specificity of the flexible electrochemical sensor for markers such as vitamin C and uric acid in PBS buffer solution were investigated by DPV, and the open circuit voltage (E OCV ); Finally, the electrochemical sensor detects vitamin C and uric acid in human sweat and transmits the monitoring signal to the mobile phone via Bluetooth device, realizing the home detection function of human metabolites.

[0047] Figure 6 The sensor is placed in a complex environment (human sweat) to record the E of uric acid (UA) at different levels. OCV Signal response diagram. The results show that the sensor can realize in-situ detection of UA in sweat without an external power supply, and the output signal is good and stable.

[0048] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0049] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polypeptide composite hydrogel material, characterized in that: include: L-type polypeptide powder and reduced graphene oxide; The L-type polypeptide powder is (Nap) 2kkf; In the above formula, (Nap)2 represents k represents lysine; f represents phenylalanine.

2. A method for preparing a composite hydrogel material as claimed in claim 1, characterized in that: include: The L-type polypeptide powder was dissolved in DMSO solvent to prepare a polypeptide solution, and then the polypeptide solution was diluted with reduced graphene oxide aqueous solution and allowed to stand to obtain the rGOx / Pep composite hydrogel.

3. The method for preparing a composite hydrogel material according to claim 2, characterized in that: The concentration of the polypeptide solution is 150 mg / mL, the concentration of the reduced graphene oxide aqueous solution is 2 mg / mL, and the dilution is performed to dilute the polypeptide solution to a concentration of 5 mg / mL.

4. The method for preparing a composite hydrogel material according to claim 2, characterized in that: The standing time is 0.5h.

5. A wearable electrochemical sensor, characterized in that: The composite hydrogel according to claim 1 is modified onto the interface of a flexible printed electrode by a drop coating method to obtain the sensor.

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