Electric biosensor and preparation method thereof

Abstract

The invention provides an electric biosensor and a preparation method thereof, and relates to the technical field of biosensing. The electric biosensor comprises a screen-printed electrode and a plurality of probes, the screen printing electrode comprises at least three working electrodes, a reference electrode and a counter electrode, the counter electrode is arranged in an area defined by the multiple working electrodes, the reference electrode is located between the counter electrode and the working electrodes, and the reference electrode is arranged around the working electrodes; each working electrode is of a circular plane structure, a carboxylated g-C3N4 thin film layer modified by ternary noble metal is formed on the surface of each working electrode, and each thin film layer comprises a gradient composite structure sequentially formed by rhodium, platinum and gold; the probes and the working electrodes are arranged in a one-to-one correspondence mode, and at least part of the probes are matched with different types of target objects. The electric biosensor has relatively high biocompatibility and stability, can be used for multi-target detection, and improves the adaptability to complex analysis requirements.

Description

Technical Field

[0001] The present disclosure relates to the field of biosensor technology, and in particular, to a biosensor and a method for preparing the same. Background Art

[0002] An electrochemical biosensor (also called an electro-biosensor) is an analytical device that combines a bio-recognition element with an electrochemical transducer. It generates a detectable electrochemical signal through the specific interaction between the bio-recognition element (such as enzymes, antibodies, DNA, cells, etc.) and the target analyte, thereby achieving quantitative or qualitative detection of the target analyte. Due to its high sensitivity and fast response speed, electro-biosensors have broad application prospects in the fields of medicine, environment, food, scientific research and industry.

[0003] At present, due to the material and performance limitations of the sensor materials, the commonly used electrical biosensors have poor stability and low binding efficiency between the sensor and the biological probe, which in turn affects the detection sensitivity and detection results of the sensor. In addition, the sensor itself has poor applicability and can only detect a single target analyte.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In view of this, an electrical biosensor and a preparation method thereof are provided. The electrical biosensor forms a ternary precious metal-modified carboxylated g-C3N4 thin film layer on the working electrode, so that each working electrode can be adapted to different types of probes. The electrical biosensor can be used for the detection of multiple targets and has good stability and high detection sensitivity.

[0006] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by the practice of the present disclosure.

[0007] According to one aspect of the present disclosure, there is provided an electrical biosensor, the electrical biosensor comprising: Screen-printed electrodes, the screen-printed electrodes comprising at least three working electrodes, a reference electrode and a counter electrode, the counter electrode being arranged in an area surrounded by the plurality of working electrodes, the reference electrode being located between the counter electrode and the working electrode, and the reference electrode being arranged around each of the working electrodes; Wherein, each of the working electrodes has a circular planar structure, and a carboxylated g-C3N4 thin film layer modified with a ternary noble metal is formed on the surface of each of the working electrodes, wherein the thin film layer includes a gradient composite structure formed by rhodium, platinum, and gold in sequence; A plurality of probes are provided corresponding to the working electrodes in a one-to-one manner, the probes are used to detect targets, and at least some of the probes are adapted to different types of targets.

[0008] In an exemplary embodiment of the present disclosure, the thickness of the thin film layer is 100nm~500nm, rhodium, platinum and gold are formed in sequence from the working electrode to the direction of the probe, and the mass ratios of rhodium, platinum and gold doped in the thin film layer are 0.1%~0.3%, 0.2%~0.5% and 0.3%~0.6% respectively.

[0009] In an exemplary embodiment of the present disclosure, the ratio of the distance between two adjacent working electrodes to the diameter of the working electrodes is greater than or equal to three.

[0010] In an exemplary embodiment of the present disclosure, the portion of the reference electrode surrounding each of the working electrodes is a semi-wrapped concentric ring structure, the reference electrode covers 30% to 60% of the circumference of the working electrode, and the area of ​​the reference electrode is 15% to 20% of the total area of ​​the working electrode.

[0011] In an exemplary embodiment of the present disclosure, the counter electrode adopts a continuously bent serpentine structure, and the serpentine structure of the counter electrode includes at least 5 periodic bending units, the bending angle of each bending unit is 90°~135°, and the bending line width of each bending unit is 0.5mm~1mm.

[0012] According to another aspect of the present disclosure, a method for preparing an electrical biosensor is provided, the method comprising: Forming initial screen-printed electrodes, the initial screen-printed electrodes comprising at least three initial working electrodes, a counter electrode and a reference electrode, wherein the reference electrode is located between the counter electrode and the initial working electrode, and the portion of the reference electrode surrounding each of the initial working electrodes is in a semi-wrapped concentric ring structure, and the counter electrode is in a continuously bent serpentine structure; Forming a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each of the initial working electrodes to form a working electrode, wherein the thin film layer includes a gradient composite structure formed by rhodium, platinum, and gold in sequence; Probes are formed on each of the working electrodes, and at least some of the probes are adapted to detect targets of different types.

[0013] In an exemplary embodiment of the present disclosure, the forming of a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each of the initial working electrodes comprises: Preparation of few-layer ternary noble metal modified g-C3N4 powder; Carboxylating the few-layer ternary noble metal-modified g-C3N4 powder to obtain a ternary noble metal-modified carboxylated g-C3N4 dispersion; The ternary noble metal-modified carboxylated g-C3N4 dispersion is sprayed on each of the initial working electrodes to form a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each of the initial working electrodes.

[0014] In an exemplary embodiment of the present disclosure, the preparation of a few-layer ternary noble metal-modified g-C3N4 powder comprises: preparing g-C3N4 precursor powder; Placing the g-C3N4 precursor powder in a mixed solution, and refluxing at a first preset temperature for a preset time, wherein the mixed solution comprises ethanol and glycerol in a volume ratio of not less than 3, the first preset temperature is 80°C to 90°C, and the preset time is 4h to 8h; During the reflux process, rhodium nitrate, chloroplatinic acid and chloroauric acid are sequentially added to the mixed solution at intervals, and the addition amounts of the rhodium nitrate, the chloroplatinic acid and the chloroauric acid are 0.1% to 0.3%, 0.2% to 0.5% and 0.3% to 0.6% of the mass of the g-C3N4 precursor powder, respectively, and the mixture is filtered and dried to obtain a ternary noble metal-modified g-C3N4 precursor powder; The g-C3N4 precursor powder modified with the ternary noble metal is subjected to a first heat treatment to obtain a few-layer ternary noble metal modified g-C3N4 powder.

[0015] In an exemplary embodiment of the present disclosure, the first heat treatment includes: The ternary noble metal modified g-C3N4 precursor powder is heated to a first temperature and kept warm for a first time to obtain ternary noble metal modified g-C3N4 powder, wherein the first temperature is 550°C to 650°C, the first time is 1h to 2h, and the heating rate is 2°C / min to 5°C / min; The ternary noble metal modified g-C3N4 powder is kept at a second temperature for a second time to obtain the few-layer ternary noble metal modified g-C3N4 powder, wherein the second temperature is 500°C to 550°C, and the second time is 1h to 2h.

[0016] In an exemplary embodiment of the present disclosure, the preparation of the precursor powder of g-C3N4 comprises: Dissolving melamine and urea powder in a deionized water solution, and then adding a preset amount of solid phosphorous acid to obtain a nitrogen-rich g-C3N4 precursor aqueous solution, wherein the mass ratio of melamine to urea is greater than or equal to 2; After the nitrogen-rich g-C3N4 precursor aqueous solution is subjected to a second heat treatment, it is filtered and rinsed to obtain the g-C3N4 precursor powder. The insulation temperature of the second heat treatment is 160°C~180°C, and the insulation time is 12h~16h.

[0017] The electrical biosensor provided by the present disclosure is provided with at least three working electrodes, and a carboxylated g-C3N4 thin film layer modified with a ternary precious metal is formed on each working electrode, and the thin film layer includes a gradient composite structure formed by rhodium, platinum and gold in sequence. Through the multi-scale synergistic effect of rhodium, platinum and gold, the biocompatibility of each working electrode can be improved, the binding efficiency and stability of the working electrode and the probe are improved, the test sensitivity can be improved, and then the accuracy of the detection result is improved; the electrical biosensor can perform repeatable detection; in addition, because the multiple working electrodes of the electrical biosensor can match different types of targets, simultaneous detection of multiple targets can be achieved, the detection efficiency is improved, and it is adaptable to various complex analysis requirements.

[0018] The preparation method of the electrical biosensor provided in the present disclosure can form a ternary precious metal-modified carboxylated g-C3N4 thin film layer on multiple working electrodes in the electrical biosensor, thereby forming an electrical biosensor with good stability and high sensitivity, which can match different targets and is suitable for multi-target detection.

[0019] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0021] Figure 1 Schematic diagram of the structure of an electrical biosensor with six working electrodes in an exemplary embodiment of the present disclosure.

[0022] Figure 2 Schematic diagram of the structure of an electrical biosensor with five working electrodes in an exemplary embodiment of the present disclosure.

[0023] Figure 3 Schematic diagram of the structure of an electrical biosensor with four working electrodes in an exemplary embodiment of the present disclosure.

[0024] Figure 4 Schematic diagram of the structure of an electrical biosensor with three working electrodes in an exemplary embodiment of the present disclosure.

[0025] Figure 5 4 is a curve relationship diagram of the film layer thickness, the probe adsorption amount and the peak current in the exemplary embodiment of the present disclosure.

[0026] Figure 6 4 is a curve relationship diagram of the rhodium doping ratio, peak current and base current in the exemplary embodiment of the present disclosure.

[0027] Figure 7 Graph showing the relationship between the platinum doping ratio and the working electrode impedance in an exemplary embodiment of the present disclosure.

[0028] Figure 8 4 is a graph showing the relationship between the gold doping ratio and the probe adsorption amount in an exemplary embodiment of the present disclosure.

[0029] Fig. 9 : This is the XRD spectrum of the carboxylated g-C3N4 thin film layer modified with ternary noble metals in the exemplary embodiment of the present disclosure.

[0030] Fig.10 3 is a SEM image of a carboxylated g-C3N4 thin film layer modified with a ternary noble metal in an exemplary embodiment of the present disclosure.

[0031] Fig.11 TEM image of the carboxylated g-C3N4 thin film layer modified with ternary noble metals in an exemplary embodiment of the present disclosure.

[0032] Fig.12 3 is a STEM element distribution diagram of the carboxylated g-C3N4 thin film layer modified with ternary noble metals in an exemplary embodiment of the present disclosure.

[0033] Fig.13 In the exemplary embodiment of the present disclosure Fig.12 Corresponding STEM elemental distribution map of rhodium in the ternary noble metal modified carboxylated g-C3N4 thin film layer.

[0034] Fig.14 In the exemplary embodiment of the present disclosure Fig.12 Corresponding STEM elemental distribution map of platinum in the ternary noble metal modified carboxylated g-C3N4 thin film layer.

[0035] Fig.15 In the exemplary embodiment of the present disclosure Fig.12 Corresponding STEM elemental distribution map of gold in the ternary noble metal modified carboxylated g-C3N4 thin film layer.

[0036] Fig.16 This is a Raman test image of the carboxylated g-C3N4 thin film layer modified with ternary noble metals in an exemplary embodiment of the present disclosure.

[0037] Fig.17 4 is a Fourier infrared spectrum of the carboxylated g-C3N4 thin film layer modified with ternary noble metals in an exemplary embodiment of the present disclosure.

[0038] Fig.18 The present invention is a flowchart of a method for preparing an electrical biosensor according to an exemplary embodiment of the present invention.

[0039] The reference numerals are described as follows: W, working electrode; S1, reference electrode; S2, counter electrode. DETAILED DESCRIPTION

[0040] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0041] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of the illustration to another component, these terms are used in this specification only for convenience, such as according to the orientation of the examples described in the drawings. It is understood that if the device of the illustration is turned upside down, the component described as "upper" will become the component "lower". When a structure is "on" other structures, it may mean that the structure is formed integrally on the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through another structure.

[0042] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express an open-ended inclusive meaning and mean that additional elements / components / etc. may exist in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used merely as labels and are not intended to limit the quantity of their objects.

[0043] Among the related technologies, electrochemical biosensors can achieve high sensitivity and rapid response, especially in the field of multi-target analysis, and have unique advantages. However, due to the limited electrochemical properties of existing sensor materials, the binding rate between the sensor and the biological probe reaches a bottleneck, making it difficult to achieve efficient detection of the target analyte. In addition, the existing sensors and target analytes are usually detected one-to-one, resulting in low detection efficiency.

[0044] Based on this, the present disclosure provides an electrical biosensor, such as Figure 1 As shown, combined Figures 2 to 4 The electrical biosensor includes: a screen-printed electrode and a plurality of probes.

[0045] Among them, the screen-printed electrode includes at least three working electrodes, a reference electrode and a counter electrode, the counter electrode is arranged in the area surrounded by the multiple working electrodes, the reference electrode is located between the counter electrode and the working electrode, and the reference electrode is arranged around each working electrode; wherein each working electrode is a circular planar structure, and a carboxylated g-C3N4 (Graphitic Carbon Nitride, graphite phase carbon nitride) thin film layer modified by a ternary precious metal is formed on the surface of each working electrode, and the thin film layer includes a gradient composite structure formed by rhodium, platinum and gold in sequence; the probes are arranged in a one-to-one correspondence with the working electrodes, the probes are used to detect the target, and at least some of the probes are adapted to different types of targets.

[0046] The electrical biosensor provided by the present disclosure is provided with at least three working electrodes, and a carboxylated g-C3N4 thin film layer modified with a ternary precious metal is formed on each working electrode, and the thin film layer includes a gradient composite structure formed by rhodium, platinum and gold in sequence. Through the multi-scale synergistic effect of rhodium, platinum and gold, the biocompatibility of each working electrode can be improved, the binding efficiency and stability of the working electrode and the probe are improved, the test sensitivity can be improved, and then the accuracy of the detection result is improved; the electrical biosensor can perform repeatable detection; in addition, because the multiple working electrodes of the electrical biosensor can match different types of targets, simultaneous detection of multiple targets can be achieved, the detection efficiency is improved, and it is adaptable to various complex analysis requirements.

[0047] The following will describe in detail the various parts of the electrical biosensor provided by the embodiment of the present disclosure in conjunction with the accompanying drawings: In the embodiments provided in the present disclosure, the electrical biosensor includes screen-printed electrodes, and the screen-printed electrodes include at least three working electrodes, a reference electrode and a counter electrode. In the following embodiments of the present disclosure, the electrical biosensor is referred to as a sensor for short. It should be understood that the sensor provided in the present disclosure includes other structures necessary for the operation of the sensor, such as an electrode interface, etc., in addition to the working electrode, the counter electrode and the reference electrode. These other necessary structures are arranged in the sensor of the present disclosure to provide a structural basis for the normal operation of the sensor. These other necessary structures are not described in detail here.

[0048] The working electrode, reference electrode and counter electrode can all be prepared by screen printing technology. The screen printing technology can improve the shape accuracy and relative positional relationship of each electrode, providing a structural basis for the subsequent preparation of electrical biosensors.

[0049] Among them, the working electrode can be prepared by silver paste. Since silver paste has the characteristic of low resistance, the sensitivity of the sensor can be improved. The electrical biosensor also includes a wire printed with silver paste, which is used to form an electrical connection between each working electrode and an external device. The working electrode has a circular planar structure, which can solve the problem of uneven current density caused by edge effect and improve the performance of each working electrode. Each working electrode has a circular planar structure, and the diameters of multiple working electrodes can be all the same, partially the same, or all different. The sizes of multiple working electrodes can be selected and adaptively adjusted according to the actual design and use requirements of the sensor, but in order to simplify the manufacturing process and improve the versatility of the sensor, multiple working electrodes can adopt a structure with all the same diameters.

[0050] In order to meet the multi-target detection requirements of the sensor, the number of working electrodes is at least three, for example, the working electrodes can be three, four, five, six or even more, and the number of working electrodes can be determined according to the specific structural design requirements of the sensor and the number and type of targets, and the present disclosure does not make specific limitations. Multiple working electrodes can be arranged in an array to form an array-type electrical biosensor, which is more conducive to improving the reliability of multi-target detection.

[0051] Taking the structure in which multiple working electrodes adopt the same diameter as an example, the ratio of the distance between two adjacent working electrodes to the diameter of the working electrode is greater than or equal to 3, which can effectively suppress the overlap of the diffusion layers of adjacent electrodes and ensure the stability of the sensor structure. Specifically, the diameter of the working electrode can be 1mm~3mm, for example, it can be 1mm, 1.5mm, 2mm, 2.5mm or 3mm, etc.; the distance between adjacent working electrodes can be 3mm~9mm, for example, it can be 3mm, 4mm, 5mm, 6mm, 7mm, 8mm or 9mm, etc. The diameter of each working electrode and the distance between adjacent working electrodes are within the above range. It is necessary to ensure that the ratio of the distance between adjacent working electrodes to the diameter of the working electrode is greater than or equal to 3. For example, when the diameter of the working electrode is 2mm, the distance between adjacent working electrodes can be 6mm or more. It should be noted that the distance between two adjacent working electrodes in the present disclosure refers to the minimum distance between the two working electrodes.

[0052] The surface of each working electrode is formed with a carboxylated g-C3N4 thin film layer modified with ternary noble metals, and the thin film layer includes a gradient composite structure formed by rhodium, platinum and gold in sequence. Through the multi-scale synergistic mechanism between the ternary noble metals, the binding efficiency of the sensor and the probe is improved, the detection sensitivity, stability and reliability of the sensor are improved, and the overall performance of the sensor is improved.

[0053] Among them, rhodium, platinum and gold are formed in sequence from the working electrode to the direction of the probe. In the process of forming the thin film layer on the working electrode, a g-C3N4 layer is first formed on the working electrode, and then rhodium is reduced and deposited on the surface of the g-C3N4 layer to form a catalytically active core layer, which effectively promotes the proton reduction reaction and increases the sensitivity and selectivity of the sensor; then platinum is formed on the basis of rhodium, and platinum is used to construct an electron transmission channel, and carriers are separated by Schottky junction technology of the metal-semiconductor cross-section, so as to improve the speed and reliability of electron transmission; finally, gold is formed on the basis of platinum, and gold forms a specific surface structure in the outermost layer, and its thiol group binding site is conducive to the directional adsorption of the probe molecules, so as to improve the binding efficiency between the working electrode and the probe, thereby improving the detection sensitivity and stability of the sensor. In the present disclosure, the gradient composite structure formed by the ternary noble metals in the thin film layer can be exposed through the catalytic active points of rhodium, and jointly realize cross-scale coupling with the electronic bridge effect of platinum. The ternary noble metals work synergistically with each other to improve the catalytic efficiency, electron transfer efficiency and probe binding efficiency. Compared with a single noble metal element, it is not a simple superposition of functions, but complements each other to jointly enhance the functionality of the sensor.

[0054] Specifically, the mass ratio of rhodium doping in the thin film layer can be 0.1% to 0.3%, for example, it can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc. Figure 6 As shown, Figure 6 The graph shows the change curve of the DPV (Differential Pulse Voltammetry) peak current of the working electrode at different rhodium doping ratios. It can be seen from the figure that with the increase of the rhodium doping ratio, the DPV peak current gradually increases, but the background signal dark current will also increase. When the rhodium doping ratio is about 0.2%, the DPV peak current reaches the maximum value, that is, the rhodium doping ratio of 0.2% is the best ratio. However, it should be noted that when the mass ratio of rhodium doping in the film layer is in the range of 0.1%~0.3%, rhodium has a good performance improvement on the working electrode.

[0055] The mass ratio of platinum doping in the thin film layer can be 0.2% to 0.5%, for example, it can be 0.2%, 0.3%, 0.4%, 0.5%, etc. Figure 7 As shown, Figure 7 The impedance curves of platinum at different doping ratios are shown in the figure. It can be seen from the figure that as the platinum doping ratio increases, the impedance arc radius decreases, and the electron transmission effect is better. However, due to cost factors and the limitation of component composition ratio, the platinum doping ratio of 0.4% is the best ratio. However, it should be noted that when the mass ratio of platinum doping in the film layer is in the range of 0.2%~0.5%, platinum has a good performance improvement on the working electrode.

[0056] The mass ratio of gold doping in the thin film layer can be 0.3% to 0.6%, for example, it can be 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, etc. Figure 8 As shown, Figure 8 The adsorption of probe by gold at different doping ratios is shown in the figure. It can be seen from the figure that as the gold doping ratio increases, the adsorption of probe increases, and the better the probe adsorption effect, the peak of the probe adsorption is reached when the gold doping ratio is 0.5%. Therefore, the gold doping ratio of 0.5% is the best ratio. However, it should be noted that when the mass ratio of gold doping in the film layer is in the range of 0.3% to 0.6%, gold has a good effect on improving the performance of the working electrode.

[0057] In addition, due to the introduction of precious metal gold, the adsorption capacity of the working electrode to the probe is increased, that is, the binding efficiency between the working electrode and the probe is improved, and this working electrode is suitable for various types of probes. For example, the probe can be one or more of aptamers, enzymes, and antibodies, which improves the application range of the sensor and its adaptability to complex detection tasks.

[0058] The film layer also includes carboxylated g-C3N4. By introducing carboxyl functional groups into g-C3N4, the biocompatibility of the sensor is further improved, and the stability and detection sensitivity of the sensor are improved. The carboxylated g-C3N4 is combined with ternary noble metal modification to form a film layer, which can improve the overall functionality of the sensor. The thickness of the film layer can be 100nm~500nm, for example, 100nm, 200nm, 300nm, 400nm, 500nm, etc. Figure 5 A curve chart showing the relationship between the thickness of the thin film layer and the probe adsorption amount shows that, as the thickness of the thin film layer increases, the probe adsorption amount increases, but the peak current decreases, that is, due to the semiconductor properties of the device, as the thickness of the thin film layer increases, the peak current of the sensor decreases, resulting in a decrease in the sensitivity of the sensor. Therefore, in order to increase the probe adsorption amount while ensuring the sensitivity of the sensor, the thickness of the thin film layer is in the range of 100nm~500nm. Furthermore, when the thickness of the thin film layer is 200nm, the probe adsorption amount and the peak current can reach the optimal balance point, that is, the optimal thickness of the thin film layer is 200nm.

[0059] Among them, the reference electrode can be prepared by silver chloride. Since the reference electrode needs to provide a stable potential reference point for the working electrode in the sensor, the silver chloride reference electrode has a small potential drift and a fast response speed, which can improve the potential measurement accuracy and reliability of the working electrode.

[0060] The reference electrode is located between the counter electrode and the working electrode, and the reference electrode is arranged around each working electrode. The portion of the reference electrode surrounding each working electrode is a semi-wrapped concentric ring structure to improve the uniformity and stability of the potential around each working electrode. Among them, the proportion of the reference electrode covering the circumference of the working electrode is 30% to 60%, for example, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc. Within the above range, it not only ensures the uniformity and stability of the potential around the working electrode, but also reduces the response time delay. Among them, the area of ​​the reference electrode is 15% to 20% of the total area of ​​the working electrode, for example, it can be 15%, 16%, 17%, 18%, 19%, 20%, etc., to further ensure the stability of the reference potential. By adjusting the ratio of the circumference and area between the reference electrode and the working electrode, the stability of the reference electrode can be ensured, and the performance of the sensor can be further improved.

[0061] Among them, the counter electrode can be prepared by carbon slurry. Since the counter electrode needs to ensure the closure of the circuit and the stability of the current flow in the sensor, the carbon counter electrode has high conductivity and chemical stability, which can ensure the circuit closure of the sensor and improve the stability of the current flow.

[0062] The counter electrode is arranged in the area surrounded by multiple working electrodes, and the counter electrode adopts a continuously bent serpentine structure, which reduces the electrode polarization while increasing or decreasing the reaction current, thereby improving the accuracy and stability of the detection. Among them, the serpentine structure of the counter electrode can include at least 5 periodic bending units, each bending unit has a bending angle of 90°~135°, and each bending unit has a bending line width of 0.5mm~1mm, which improves the functionality of the counter electrode while increasing the service life of the counter electrode. In addition, the overall shape of the serpentine structure of the counter electrode needs to match the working electrode and the reference electrode. On the one hand, it can avoid structural interference between the electrodes and cause the sensor function to decline, and on the other hand, it can also improve the compactness of the sensor structure.

[0063] In some specific embodiments, Figures 1 to 4 As shown in FIG. 1 , the number of working electrodes of the sensor is 3, 4, 5, and 6 respectively. Figure 1 As shown, when the number of working electrodes is 6, the 6 working electrodes are evenly and symmetrically distributed on both sides of the counter electrode and each working electrode adopts a circular structure with the same diameter, the reference electrode is located between the counter electrode and the working electrode, the counter electrode and the reference electrode are in an axisymmetric structure, and the reference electrode is semi-wrapped around each working electrode, and the counter electrode is in a first serpentine structure with continuous bending. The symmetrical structure of the sensor can improve the stability and practicality of the device, reduce detection errors, improve the performance of the device, and facilitate the simplification of the manufacturing process.

[0064] like Figure 2As shown, when the number of working electrodes is 5, a counter electrode and a reference electrode having the same structure as the six working electrodes can be used. When setting the position of the working electrodes, one working electrode can be reduced based on the six working electrode structures. It should be noted that when the number of working electrodes is 5, a reference electrode and a counter electrode having different structures from the six working electrodes can also be used, and the structures of the reference electrode and the counter electrode can be adaptively adjusted and changed to adapt to changes in the number of working electrodes.

[0065] like Figure 3 As shown, when the number of working electrodes is 4, the 4 working electrodes are evenly and symmetrically distributed on both sides of the counter electrode and each working electrode adopts a circular structure with the same diameter, the reference electrode is located between the counter electrode and the working electrode, the counter electrode and the reference electrode are axially symmetrical, and the reference electrode is semi-wrapped around each working electrode, and the counter electrode is a continuously bent second serpentine structure, wherein the second serpentine structure is different from the first serpentine structure, and the number of bending units of the second serpentine structure is less than the number of bending units of the first serpentine structure.

[0066] like Figure 4 As shown, when the number of working electrodes is 3, a counter electrode and a reference electrode having the same structure as the four working electrodes can be used. When setting the position of the working electrodes, one working electrode can be reduced based on the four working electrode structures. It should be noted that when the number of working electrodes is 3, a reference electrode and a counter electrode having different structures from the four working electrodes can also be used, and the structures of the reference electrode and the counter electrode can be adaptively adjusted and changed to adapt to changes in the number of working electrodes.

[0067] In the embodiments provided in the present disclosure, the electrical biosensor includes a plurality of probes, and the probes are arranged in a one-to-one correspondence with the working electrodes. The probes are used to detect the target, and at least some of the probes are adapted to different types of targets. Among them, the probes may be one or more of aptamers, antibodies, and enzymes. The probes are arranged on the working electrodes. Since there are multiple working electrodes in the sensor, the probes may be arranged on all the working electrodes, or on some of the working electrodes. However, in order to improve the utilization rate of the sensor, probes are usually arranged on each working electrode. Among them, at least some of the probes are adapted to different types of targets, so as to realize the detection of different types of targets by the sensor, thereby improving the adaptability of the sensor to complex detection requirements and complex analysis requirements.

[0068] The electrical biosensor provided by the present disclosure is provided with at least three working electrodes, and a carboxylated g-C3N4 thin film layer modified with a ternary precious metal is formed on each working electrode, and the thin film layer includes a gradient composite structure formed by rhodium, platinum and gold in sequence. Through the multi-scale synergistic effect of rhodium, platinum and gold, the biocompatibility of each working electrode can be improved, the binding efficiency and stability of the working electrode and the probe can be improved, the test sensitivity can be improved, and then the accuracy of the detection result can be improved; the electrical biosensor can perform repeatable detection; in addition, because the multiple working electrodes of the electrical biosensor can match different types of targets, simultaneous detection of multiple targets can be achieved, the detection efficiency is improved, and it is adaptable to various complex analysis requirements and complex detection requirements.

[0069] The present disclosure provides a method for preparing an electrical biosensor, such as Fig.18 As shown, the method for preparing the electrical biosensor includes: step S10 to step S30.

[0070] Wherein, step S10: forming an initial screen-printed electrode, the initial screen-printed electrode comprising at least three initial working electrodes, a counter electrode and a reference electrode, wherein the reference electrode is located between the counter electrode and the initial working electrode, and the portion of the reference electrode surrounding each initial working electrode is a semi-wrapped concentric ring structure, and the counter electrode adopts a continuously bent serpentine structure; Step S20: forming a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each initial working electrode to form a working electrode, wherein the thin film layer includes a gradient composite structure formed of rhodium, platinum, and gold in sequence; Step S30: forming probes on each working electrode respectively, wherein at least some of the probes are adapted to different types of detection targets.

[0071] The preparation method of the electrical biosensor provided in the present disclosure can form a ternary precious metal-modified carboxylated g-C3N4 thin film layer on multiple working electrodes in the electrical biosensor, thereby forming an electrical biosensor with good stability and high sensitivity. The electrical biosensor can match various types of targets and is suitable for multi-target detection, thereby improving the adaptability of the sensor to complex detection requirements and complex analysis requirements, thereby improving the performance of the sensor.

[0072] It should be noted that the preparation method provided in the present disclosure can be used to prepare any of the electrical biosensors provided in the above embodiments.

[0073] The following is a detailed description of each step of the method for preparing the electrical biosensor provided in the embodiment of the present disclosure: In an embodiment provided by the present disclosure, in step S10, an initial screen-printed electrode is formed, and the initial screen-printed electrode includes at least three initial working electrodes, a counter electrode and a reference electrode.

[0074] Among them, the initial screen-printed electrode is prepared by screen printing process, each initial working electrode is prepared by silver paste, the reference electrode is prepared by silver chloride, and the counter electrode is prepared by carbon paste; in addition, it also includes silver paste wires prepared by screen printing process, which are used to realize electrical connection between the working electrode and external devices.

[0075] Each initial working electrode has a circular planar structure, the reference electrode is formed between the counter electrode and the initial working electrode, and the reference electrode is arranged around each initial working electrode, and the portion of the reference electrode surrounding each initial working electrode is a semi-wrapped concentric ring structure, the counter electrode is arranged in the area surrounded by the multiple initial working electrodes, and the counter electrode adopts a continuously bent serpentine structure. The specific shapes and structural parameters of the counter electrode and the reference electrode are the same as the data provided in the above embodiment, and will not be repeated here.

[0076] In the embodiment provided in the present disclosure, in step S20, a ternary noble metal-modified carboxylated g-C3N4 thin film layer is formed on each initial working electrode to form a working electrode.

[0077] The process of forming a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each initial working electrode includes steps S21 to S23.

[0078] Among them, step S21, prepare a few layers of ternary precious metal modified g-C3N4 powder; step S22, carboxylate the few layers of ternary precious metal modified g-C3N4 powder to obtain a ternary precious metal modified carboxylated g-C3N4 dispersion; step S23, spray the ternary precious metal modified carboxylated g-C3N4 dispersion on each initial working electrode to form a ternary precious metal modified carboxylated g-C3N4 thin film layer on each initial working electrode.

[0079] In step S21, preparing a few layers of ternary noble metal modified g-C3N4 powder includes steps S211 to S214.

[0080] Step S211, preparing g-C3N4 precursor powder; Step S212, placing the g-C3N4 precursor powder in a mixed solution, and refluxing at a first preset temperature for a preset time; Step S213, during the reflux process, sequentially adding rhodium nitrate, chloroplatinic acid, and chloroauric acid to the mixed solution at intervals, and the added amounts of rhodium nitrate, chloroplatinic acid, and chloroauric acid are 0.1%~0.3%, 0.2%~0.5%, and 0.3%~0.6% of the mass of the g-C3N4 precursor powder, respectively, and filtering and drying are performed to obtain ternary precious metal modified g-C3N4 precursor powder; Step S214, performing a first heat treatment on the ternary precious metal modified g-C3N4 precursor powder to obtain a few layers of ternary precious metal modified g-C3N4 powder.

[0081] Wherein, in step S211, preparing the g-C3N4 precursor powder includes steps S2111 and S2112. Wherein, in step S2111, melamine and urea powder are dissolved in a deionized water solution, and a preset amount of solid phosphorous acid is added to obtain a nitrogen-rich g-C3N4 precursor aqueous solution, wherein the mass ratio of melamine to urea is greater than or equal to 2; in step S2112, the nitrogen-rich g-C3N4 precursor aqueous solution is subjected to a second heat treatment, and then filtered and rinsed to obtain a g-C3N4 precursor powder, wherein the insulation temperature of the second heat treatment is 160°C to 180°C, and the insulation time is 12h to 16h.

[0082] In step S2111, melamine and urea powder are dissolved in a deionized water solution, and a preset amount of solid phosphorous acid is added, and the resulting mixed solution is stirred at a temperature of 80° C. The stirring time may be 30 min to 60 min to ensure the uniformity of the mixed solution. The mass of the preset amount of solid phosphorous acid may be 25% to 50% of the total mass of melamine and urea to promote the polycondensation reaction and avoid affecting the subsequent loading of the ternary metal due to excess phosphorous acid residue.

[0083] In step S2112, the second heat treatment may specifically be to place the nitrogen-rich g-C3N4 precursor aqueous solution in a hydrothermal reactor and heat it to 160°C to 180°C, and keep it warm for 12h to 16h. The product after the second heat treatment may be filtered and repeatedly re-filtered with ultrapure water to obtain the g-C3N4 precursor powder.

[0084] Wherein, in step S212, the mixed solution includes ethanol and glycerol in a volume ratio of not less than 3. Since ethanol has a low boiling point and glycerol has a high viscosity, the mixed solution can form a gradient heat transfer system, which is beneficial to improve the dispersion uniformity of the precursor powder of g-C3N4 during the reflux process; in addition, the strong coordination ability of the glycerol hydroxyl group can effectively anchor metal ions, inhibit the agglomeration of nanoparticles, and improve the subsequent diffusion uniformity of metal ions, thereby improving the formation quality of the subsequent thin film layer. The first preset temperature is the reflux temperature, which can be 80°C~90°C, and the preset time is the reflux time, which can be 4h~8h. The reflux temperature and reflux time can be adaptively adjusted according to the actual process design.

[0085] In step S213, during the reflux process, rhodium nitrate, chloroplatinic acid, and chloroauric acid are sequentially added to the mixed solution at intervals. Specifically, during the reflux process, after the temperature is raised to the first preset temperature, 0.1-0.3% rhodium nitrate, 0.2-0.5% chloroplatinic acid, and 0.3-0.6% chloroauric acid are sequentially added to the mixed solution at a time interval of 5-10 minutes, and the obtained product is filtered and dried to obtain a ternary noble metal modified g-C3N4 precursor powder.

[0086] In step S214, the g-C3N4 precursor powder modified with ternary precious metals is subjected to a first heat treatment to obtain a few-layer ternary precious metal modified g-C3N4 powder. The first heat treatment includes: heating the g-C3N4 precursor powder modified with ternary precious metals to a first temperature and keeping it warm for a first time to obtain a ternary precious metal modified g-C3N4 powder, wherein the first temperature is 550°C to 650°C, the first time is 1h to 2h, and the heating rate is 2°C / min to 5°C / min; keeping the g-C3N4 powder modified with ternary precious metals at a second temperature for a second time to obtain a few-layer ternary precious metal modified g-C3N4 powder, wherein the second temperature is 500°C to 550°C, and the second time is 1h to 2h.

[0087] In step S22, a few layers of ternary noble metal-modified g-C3N4 powder are carboxylated to obtain a ternary noble metal-modified carboxylated g-C3N4 dispersion.

[0088] The carboxylation treatment process includes: placing the obtained few-layer ternary precious metal-modified g-C3N4 powder in a citric acid solution with a mass fraction of 1% to 5%, and the mass ratio of the few-layer ternary precious metal-modified g-C3N4 powder to the citric acid solution is ≤100, to obtain a mixed solution of the two; placing the mixed solution in a reactor for hydrothermal reaction, and the reaction conditions are a temperature of 120°C to 160°C and a time of 6h to 8h; filtering and rinsing the product after the reaction, and drying it at 60°C for 8h to obtain ternary precious metal-modified carboxylated g-C3N4 powder; dispersing the ternary precious metal-modified carboxylated g-C3N4 powder in ultrapure water, with a powder mass fraction of 1% to 2%, and performing ultrasonic dispersion for 30min to 60min to obtain a ternary precious metal-modified carboxylated g-C3N4 dispersion.

[0089] The obtained ternary noble metal modified carboxylated g-C3N4 thin film layer is as follows Figures 9 to 17 As shown, Fig. 9 As shown, it can be seen that hydrothermal carboxylation does not affect the crystal structure of g-C3N4; Fig.10 and Fig.11As shown, they are the microscopic morphology of carboxylated g-C3N4 modified by ternary noble metals, and it can be seen that the film layer forms a good carboxyl group; Fig.12 , Fig.13 , Fig.14 and Fig.15 The distribution of ternary precious metals under TEM shows that the concentrations of the three precious metals are distributed from low to high in the order of rhodium, platinum, and gold; Figure 16 to Figure 17 As shown, it can be seen that the ternary noble metal-modified g-C3N4 powder forms carboxyl groups after hydrothermal treatment.

[0090] In step S23, the ternary noble metal modified carboxylated g-C3N4 dispersion is sprayed on each initial working electrode to form a ternary noble metal modified carboxylated g-C3N4 thin film layer on each initial working electrode. Specifically, 1 ml to 2 ml of the ternary noble metal modified carboxylated g-C3N4 dispersion is absorbed and sprayed on the initial working electrodes one by one to form a ternary noble metal modified carboxylated g-C3N4 thin film layer on each initial working electrode.

[0091] In the embodiment provided by the present disclosure, in step S30, probes are formed on each working electrode, and at least some of the probes are adapted to different types of detection targets. Specifically, a probe solution is obtained, which can be one or more of an aptamer, an antibody, and an enzyme; the probe corresponding to the target is dispersed in a phosphate buffer, and then dripped onto the working electrode having a carboxylated g-C3N4 thin film layer modified with a ternary precious metal using a glue dripping process, and incubated at 37°C for 2 hours to obtain the final electrical biosensor. Among them, a protein-free blocking solution can be used to block the non-specific binding sites of the probe.

[0092] The preparation method of the electrical biosensor provided in the present disclosure can form a ternary precious metal-modified carboxylated g-C3N4 thin film layer on multiple working electrodes in the electrical biosensor, thereby forming an electrical biosensor with good stability and high sensitivity. The electrical biosensor can match various types of targets and is suitable for multi-target detection, thereby improving the adaptability of the sensor to complex detection requirements and complex analysis requirements, thereby improving the performance of the sensor.

[0093] It should be noted that, although the steps of the method for preparing the electrical biosensor in the present disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps, etc.

[0094] The following is a description of the electrical biosensor provided by the present disclosure and its preparation method and application with specific embodiments: Example 1 Step 1: Place a PET film cut into 3 cm×6 cm in ultrapure water for 30 minutes of ultrasound, use silver paste to print conductors and six initial working electrodes, a reference electrode printed with silver chloride, and a counter electrode printed with carbon paste.

[0095] Step 2: Prepare carboxylated g-C3N4 powder modified with ternary noble metals.

[0096] 1.5 g of melamine and 0.5 g of urea powder were dissolved in 100 ml of deionized water to form a solution, and 1.0 g of solid phosphorous acid was added, and stirred at 80 ° C for 30 min until the solution was clear to obtain a nitrogen-rich g-C3N4 precursor aqueous solution; The g-C3N4 precursor aqueous solution was placed in a hydrothermal reactor and heated to 180°C for 16 h; The product obtained by hydrothermal treatment was filtered and repeatedly rinsed with ultrapure water to obtain g-C3N4 precursor powder; 1 g of g-C3N4 precursor powder was placed in a mixed solution of 100 ml of ethanol and glycerol, and refluxed at 90°C for 8 h, wherein the volume ratio of ethanol to glycerol was 4. During the reflux process, rhodium nitrate, chloroplatinic acid, and chloroauric acid were added in sequence every 10 min after the temperature was raised to the set temperature. The amounts of the three metals added were 0.3%, 0.5%, and 0.6% of the mass of the g-C3N4 precursor powder, respectively. The obtained product was filtered and dried to obtain a ternary noble metal-modified g-C3N4 precursor powder. The ternary noble metal modified g-C3N4 precursor powder was placed in a muffle furnace and heated to 600°C and kept at this temperature for 2 hours at a heating rate of 5°C / min to obtain ternary noble metal modified g-C3N4; The g-C3N4 modified with ternary noble metals was placed in a muffle furnace at 550°C for 1 hour to obtain g-C3N4 powder modified with few layers of ternary noble metals; Take 0.1g of a few-layer ternary noble metal-modified g-C3N4 powder and place it in 150ml of 5% by mass citric acid solution, then place the mixed solution in a reactor and hydroheat it at 120℃ for 8h. The obtained product is filtered and rinsed, and dried at 60℃ for 8h to obtain ternary noble metal-modified carboxylated g-C3N4 powder.

[0097] Step 3: Disperse the carboxylated g-C3N4 powder modified by the ternary noble metal in ultrapure water with a powder mass fraction of 2% and perform ultrasonic dispersion for 60 minutes to obtain a dispersion of the carboxylated g-C3N4 modified by the ternary noble metal.

[0098] Step 4: Take 2 ml of the ternary noble metal modified carboxylated g-C3N4 dispersion and spray it on the initial working electrode one by one to form a working electrode with a ternary noble metal modified carboxylated g-C3N4 thin film layer.

[0099] Step 5: The aptamer probes corresponding to the six tumor markers were modified on six working electrodes respectively. After incubation at 37° C. for 2 h, an electrical biosensor that can be used for the detection of six tumor markers was obtained.

[0100] Among them, the aptamers corresponding to the six tumor markers are shown in Table 1.

[0101] Table 1

[0102] In Table 1, AFP is alpha-fetoprotein, CEA is cancer antigen, CA125 is carbohydrate antigen 125, CA19-9 is cancer antigen 19-9, CA15-3 is carbohydrate antigen 15-3, and PSA is prostate specific antigen.

[0103] Among them, the detection results of six tumor markers obtained using the electrical biosensor provided by the present disclosure are shown in the figure, and the specific detection data are shown in Table 2.

[0104] Table 2

[0105] It can be seen from the data provided in Table 1 and Table 2 that the electrical biosensor provided by the present disclosure can be applied to the detection of different tumor markers, that is, multi-target detection can be achieved, and it is suitable for complex analysis needs and complex detection needs. The device has high sensitivity and high reliability of detection results.

[0106] Example 2 Step 1: Place a PET film cut into 3 cm×6 cm in ultrapure water for 30 minutes of ultrasound, use silver paste to print conductors and five initial working electrodes, a reference electrode printed with silver chloride, and a counter electrode printed with carbon paste.

[0107] Step 2: Prepare carboxylated g-C3N4 powder modified with ternary noble metals.

[0108] 2.0 g of melamine and 1.0 g of urea powder were dissolved in 100 ml of deionized water to form a solution, and 0.8 g of solid phosphorous acid was added, and stirred at 80 ° C for 60 min until the solution was clear to obtain a nitrogen-rich g-C3N4 precursor aqueous solution; The g-C3N4 precursor aqueous solution was placed in a hydrothermal reactor and heated to 160°C for 12 h; The product obtained by hydrothermal treatment is filtered and repeatedly rinsed with ultrapure water to obtain g-C3N4 precursor powder; 1 g of g-C3N4 precursor powder was placed in a mixed solution of 100 ml of ethanol and glycerol, and refluxed at 80-90°C for 4 h, wherein the volume ratio of ethanol to glycerol was 3. During the reflux process, rhodium nitrate, chloroplatinic acid, and chloroauric acid were added in sequence every 5 min after the temperature was raised to the set temperature. The amounts of the three metals added were 0.1%, 0.2%, and 0.3% of the mass of the g-C3N4 precursor powder, respectively. The obtained product was filtered and dried to obtain a ternary noble metal-modified g-C3N4 precursor powder. The ternary noble metal modified g-C3N4 precursor powder was heated to 550°C in a muffle furnace and kept at this temperature for 2 h at a heating rate of 2°C / min to obtain ternary noble metal modified g-C3N4; The g-C3N4 modified with ternary noble metals was placed in a muffle furnace at 500°C for 1 hour to obtain g-C3N4 powder modified with few layers of ternary noble metals; Take 0.1 g of a few layers of ternary noble metal-modified g-C3N4 powder and put it into 100 ml of 1% citric acid solution, then put the mixed solution into a reactor and hydroheat it at 160°C for 6 hours. The obtained product is filtered and rinsed, and dried at 60°C for 8 hours to obtain ternary noble metal-modified carboxylated g-C3N4 powder.

[0109] Step 3: Disperse the ternary noble metal-modified carboxylated g-C3N4 in ultrapure water with a powder mass fraction of 1% and perform ultrasonic dispersion for 30 minutes to obtain a ternary noble metal-modified carboxylated g-C3N4 dispersion.

[0110] Step 4: Take 1 ml of the ternary noble metal-modified carboxylated g-C3N4 dispersion and spray it on the initial working electrode one by one to form a working electrode with a ternary noble metal-modified carboxylated g-C3N4 thin film layer.

[0111] Step 5: Antibody probes corresponding to the five antibiotics were modified on five working electrodes respectively. After incubation at 37° C. for 2 h, an electrical biosensor that can be used for the detection of five antibiotics was obtained.

[0112] The antibodies corresponding to the five antibiotics are tetracycline monoclonal antibody, gentamicin monoclonal antibody, cyclosporine monoclonal antibody, streptomycin monoclonal antibody, and erythromycin monoclonal antibody. The detection results of the five antibiotics obtained using the electrical biosensor provided by the present disclosure are shown in Table 3.

[0113] Table 3

[0114] It can be seen from Table 3 that the electrical biosensor provided by the present disclosure can be applied to the detection of different antibiotics, that is, multi-target detection can be achieved, and is suitable for complex analysis needs and complex detection needs. The device has high sensitivity and high reliability of detection results.

[0115] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. An electrical biosensor, characterized in that: include: Screen-printed electrodes, the screen-printed electrodes comprising at least three working electrodes, a reference electrode and a counter electrode, the counter electrode being arranged in an area surrounded by the plurality of working electrodes, the reference electrode being located between the counter electrode and the working electrode, and the reference electrode being arranged around each of the working electrodes; Wherein, each of the working electrodes has a circular planar structure, and a carboxylated g-C3N4 thin film layer modified with a ternary noble metal is formed on the surface of each of the working electrodes, wherein the thin film layer includes a gradient composite structure formed by rhodium, platinum, and gold in sequence; A plurality of probes are provided corresponding to the working electrodes in a one-to-one manner, the probes are used to detect targets, and at least some of the probes are adapted to different types of targets.

2. The electrical biosensor according to claim 1, characterized in that The thickness of the thin film layer is 100nm~500nm, and rhodium, platinum and gold are formed in sequence from the working electrode to the direction of the probe, and the mass ratios of rhodium, platinum and gold doped in the thin film layer are 0.1%~0.3%, 0.2%~0.5% and 0.3%~0.6% respectively.

3. The electrical biosensor according to claim 1, characterized in that The ratio of the distance between two adjacent working electrodes to the diameter of the working electrodes is greater than or equal to three.

4. The electrical biosensor according to claim 1, characterized in that The reference electrode surrounds each of the working electrodes in a semi-wrapped concentric ring structure, the reference electrode covers 30% to 60% of the circumference of the working electrode, and the area of ​​the reference electrode is 15% to 20% of the total area of ​​the working electrode.

5. The electrical biosensor according to claim 1, characterized in that The counter electrode adopts a continuously bent serpentine structure, and the serpentine structure of the counter electrode includes at least 5 periodic bending units, the bending angle of each bending unit is 90°~135°, and the bending line width of each bending unit is 0.5mm~1mm.

6. A method for preparing an electrical biosensor, characterized in that: include: Forming initial screen-printed electrodes, the initial screen-printed electrodes comprising at least three initial working electrodes, a counter electrode and a reference electrode, wherein the reference electrode is located between the counter electrode and the initial working electrode, and the portion of the reference electrode surrounding each of the initial working electrodes is in a semi-wrapped concentric ring structure, and the counter electrode is in a continuously bent serpentine structure; Forming a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each of the initial working electrodes to form a working electrode, wherein the thin film layer includes a gradient composite structure formed by rhodium, platinum, and gold in sequence; Probes are formed on each of the working electrodes, and at least some of the probes are adapted to detect targets of different types.

7. The method for preparing the electrical biosensor according to claim 6, characterized in that: The step of forming a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each of the initial working electrodes comprises: Preparation of few-layer ternary noble metal modified g-C3N4 powder; Carboxylating the few-layer ternary noble metal-modified g-C3N4 powder to obtain a ternary noble metal-modified carboxylated g-C3N4 dispersion; The ternary noble metal-modified carboxylated g-C3N4 dispersion is sprayed on each of the initial working electrodes to form a ternary noble metal-modified carboxylated g-C3N4 thin film layer on each of the initial working electrodes.

8. The method for preparing the electrical biosensor according to claim 7, characterized in that: The method for preparing a few-layer ternary noble metal-modified g-C3N4 powder comprises: preparing g-C3N4 precursor powder; Placing the g-C3N4 precursor powder in a mixed solution, and refluxing at a first preset temperature for a preset time, wherein the mixed solution comprises ethanol and glycerol in a volume ratio of not less than 3, the first preset temperature is 80°C to 90°C, and the preset time is 4h to 8h; During the reflux process, rhodium nitrate, chloroplatinic acid and chloroauric acid are sequentially added to the mixed solution at intervals, and the addition amounts of the rhodium nitrate, the chloroplatinic acid and the chloroauric acid are 0.1% to 0.3%, 0.2% to 0.5% and 0.3% to 0.6% of the mass of the g-C3N4 precursor powder, respectively, and the mixture is filtered and dried to obtain a ternary noble metal-modified g-C3N4 precursor powder; The g-C3N4 precursor powder modified with the ternary noble metal is subjected to a first heat treatment to obtain a few-layer ternary noble metal modified g-C3N4 powder.

9. The method for preparing the electrical biosensor according to claim 8, characterized in that: The first heat treatment comprises: The ternary noble metal modified g-C3N4 precursor powder is heated to a first temperature and kept warm for a first time to obtain ternary noble metal modified g-C3N4 powder, wherein the first temperature is 550°C to 650°C, the first time is 1h to 2h, and the heating rate is 2°C / min to 5°C / min; The ternary noble metal modified g-C3N4 powder is kept at a second temperature for a second time to obtain the few-layer ternary noble metal modified g-C3N4 powder, wherein the second temperature is 500°C to 550°C, and the second time is 1h to 2h.

10. The method for preparing the electrical biosensor according to claim 8 or 9, characterized in that: The method for preparing the precursor powder of g-C3N4 comprises: Dissolving melamine and urea powder in a deionized water solution, and then adding a preset amount of solid phosphorous acid to obtain a nitrogen-rich g-C3N4 precursor aqueous solution, wherein the mass ratio of melamine to urea is greater than or equal to 2; After the nitrogen-rich g-C3N4 precursor aqueous solution is subjected to a second heat treatment, it is filtered and rinsed to obtain the g-C3N4 precursor powder. The insulation temperature of the second heat treatment is 160°C~180°C, and the insulation time is 12h~16h.

Images