Preparation method of flexible fiber biosensing system based on molecular imprinting technology, and detection and in-situ cleaning method thereof
By modifying the surface of carbon nanotube fibers with molecularly imprinted polymers, highly sensitive and selective sensors were prepared. In-situ cleaning was performed using the principle of like charge repulsion, which solved the problems of insufficient stability and reusability of biosensors and enabled long-term use of wearable devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INSTITUTE OF TECHNOLOGY (SHENZHEN) (INSTITUTE OF SCIENCE AND TECHNOLOGY INNOVATION HARBIN INSTITUTE OF TECHNOLOGY SHENZHEN)
- Filing Date
- 2024-01-09
- Publication Date
- 2026-08-04
AI Technical Summary
Existing biosensors have poor stability and reusability, making it difficult to meet the long-term use requirements of wearable devices.
A flexible fiber biosensing system based on molecular imprinting technology was adopted. MIP/CNT electrodes were prepared by modifying the surface of carbon nanotube fibers with molecularly imprinted polymers, combined with cyclic voltammetry and electrochemical methods, and in-situ cleaning was performed using the principle of like charge repulsion.
It achieves highly sensitive detection and selective identification of target substances in sweat, while the sensing electrode can be reused multiple times and maintains good stability after 50 bends.
Smart Images
Figure CN117849139B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biosensors. Background Technology
[0002] Wearable sensors refer to a type of sensor that can be directly worn on the skin or integrated into wearable fabrics to perform sensing and analysis functions. Compared to traditional sensors, wearable biosensors provide a real-time, in-situ testing method to effectively monitor human physiological signals, offering higher accuracy, sustainability, and real-time interactivity. They are of great significance for disease screening, early warning, diagnosis, prognosis, and health level monitoring.
[0003] Most reported sensors are based on patch-type planar sensors constructed from composites of metal nanomaterials and polymer thin film substrates. While these sensors achieve flexibility by incorporating a flexible substrate, they suffer from insufficient response to bending strain in the body, hindering long-term use and failing to meet wearable requirements. Secondly, most current biosensors for detecting biomarkers lack reusability, significantly increasing material consumption and production costs. Therefore, wearable sensing fabrics, compared to patch sensors, must possess both better stability and reusability.
[0004] Therefore, the development of wearable flexible sensing fabrics for monitoring biomarkers in body fluids provides a wealth of information for assessing human health levels, as well as for disease screening and diagnostic prognosis, and is of great significance and research value. Summary of the Invention
[0005] This invention aims to address the problems of poor stability and reusability of existing biosensors (working electrodes), and further provides a method for preparing a flexible fiber biosensor system based on molecular imprinting technology, as well as its detection and in-situ cleaning methods.
[0006] A method for preparing a flexible fiber biosensing system based on molecular imprinting technology, comprising the following steps:
[0007] I. Preparation of the working electrode:
[0008] ① Carbon nanotube fibers were placed in H2SO4 solution and treated with cyclic voltammetry to obtain acid-treated carbon nanotube fibers.
[0009] Specifically, the carbon nanotube fibers are produced by pulling out an array of carbon nanotubes into a film, then twisting them into oriented carbon nanotube fibers with a primary helical structure, and then twisting 5 to 50 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure; the helical angle of the oriented carbon nanotube fibers with a primary helical structure is 5° to 60°; the helical angle of the oriented carbon nanotube fibers with a secondary helical structure is 5° to 60°.
[0010] ② The acid-treated carbon nanotube fibers were placed in an electrolyte, and the acid-treated carbon nanotube fibers were electrodeposited using cyclic voltammetry to obtain the deposited carbon nanotube fibers.
[0011] The electrolyte is a mixture of ferric chloride hydrochloric acid solution, potassium chloride solution, potassium ferricyanide solution, lactic acid solution, pyrrole solution and PBS buffer.
[0012] ③ The deposited carbon nanotube fibers were placed in PBS buffer and electro-eluted using cyclic voltammetry to obtain the MIP / CNT electrode.
[0013] II. Preparation of the reference electrode:
[0014] Ag / AgCl / yarn electrodes were prepared using yarn and Ag / AgCl conductive paste.
[0015] III. Preparation of the counter electrode:
[0016] Using a dual-potential step method, carbon nanotube fibers were plated with platinum in potassium chloroplatinate solution to obtain a Pt / conductive fiber electrode.
[0017] Specifically, the carbon nanotube fibers are produced by pulling out an array of carbon nanotubes into a film, then twisting them into oriented carbon nanotube fibers with a primary helical structure, and then twisting 5 to 50 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure; the helical angle of the oriented carbon nanotube fibers with a primary helical structure is 5° to 60°; the helical angle of the oriented carbon nanotube fibers with a secondary helical structure is 5° to 60°.
[0018] IV. Assembly of the biosensor system:
[0019] Using an Ag / AgCl / yarn electrode as the reference electrode, a Pt / conductive fiber electrode as the counter electrode, and a MIP / CNT electrode as the working electrode, the reference electrode, counter electrode, and working electrode constitute a flexible fiber biosensing system based on molecular imprinting technology.
[0020] A detection and in-situ cleaning method for a flexible fiber biosensing system based on molecular imprinting technology, comprising the following steps:
[0021] Using an Ag / AgCl / yarn electrode as the reference electrode, a Pt / conductive fiber electrode as the counter electrode, and a MIP / CNT electrode as the working electrode, the reference electrode, counter electrode, and working electrode were all placed in a PBS buffer containing lactic acid and incubated for 1 to 5 minutes. After incubation, the it curve was measured. Then, under the conditions of -1.0V to 0V and a scan rate of 0.05V / s to 0.2V / s, the working electrode after detection was electroeluted in situ for 5 to 10 seconds using linear scanning voltammetry, thus completing the detection and cleaning method. The concentration of lactic acid in the PBS buffer containing lactic acid was 5 mmol / L to 50 mmol / L. The PBS buffer containing lactic acid was 10×PBS buffer with a pH of 7.4.
[0022] The beneficial effects of this invention are:
[0023] This invention modifies the surface of carbon nanotube fibers with molecularly imprinted polymers (MIPs) to prepare a sensor with high sensitivity and selectivity for analytes in sweat. Simultaneously, through the principle of like charge repulsion, the surface of the sensing electrode can be cleaned in situ, allowing the electrode to be reused and exhibiting repeatability. For example, after incubation in a lactic acid solution, lactic acid molecules can specifically bind to the cavities formed by the MIPs. Lactic acid generally carries a negative charge under neutral or weakly alkaline conditions. By applying a negative voltage to the sensing electrode, the like charge repulsion removes the lactic acid molecules bound to the MIPs, allowing the electrode to be reused multiple times. Furthermore, after 50 bends, the sensor current maintains good stability, remaining essentially at the initial level.
[0024] Instruction manual illustrations
[0025] Figure 1 This is a schematic diagram of the structure of the carbon nanotube fiber described in step one ① and step three of the present invention;
[0026] Figure 2 This is a schematic diagram of the MIP / CNT electrode mechanism prepared in step ③ of the present invention;
[0027] Figure 3 The flowchart shows the preparation, testing, and in-situ cleaning of the MIP / CNT electrode prepared in step 3 of Example 1.
[0028] Figure 4 This is a diagram illustrating the cleaning mechanism of the MIP / CNT electrode prepared in step ③ of this invention.
[0029] Figure 5The image shown is an electron microscope image of the carbon nanotube fibers described in step 1① of Example 1.
[0030] Figure 6 The response performance diagram of the MIP / CNT electrode prepared in step 1③ of Example 1;
[0031] Figure 7 The graph shows the detection performance of the MIP / CNT electrode prepared in step 1③ of Example 1 against lactic acid solutions of different concentrations. a is the it current value detected in lactic acid solutions of different concentrations, and b is the linear fit made based on graph a.
[0032] Figure 8 The anti-interference performance diagram of the MIP / CNT electrode prepared in step 1③ of Example 1;
[0033] Figure 9 To compare the detection performance of the NIP / CNT electrode prepared in step 1③ of the experiment on lactic acid solutions of different concentrations;
[0034] Figure 10 This is a graph showing the regeneration performance of the MIP / CNT electrode in Example 2;
[0035] Figure 11 This is a stability diagram of the MIP / CNT electrode after bending in Example 2. Detailed Implementation
[0036] Specific implementation method one: Combining Figure 1 and Figure 2 Specifically, this embodiment describes a method for preparing a flexible fiber biosensing system based on molecular imprinting technology, which is carried out according to the following steps:
[0037] I. Preparation of the working electrode:
[0038] ① Carbon nanotube fibers were placed in H2SO4 solution and treated with cyclic voltammetry to obtain acid-treated carbon nanotube fibers.
[0039] Specifically, the carbon nanotube fibers are produced by pulling out an array of carbon nanotubes into a film, then twisting them into oriented carbon nanotube fibers with a primary helical structure, and then twisting 5 to 50 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure; the helical angle of the oriented carbon nanotube fibers with a primary helical structure is 5° to 60°; the helical angle of the oriented carbon nanotube fibers with a secondary helical structure is 5° to 60°.
[0040] ② The acid-treated carbon nanotube fibers were placed in an electrolyte, and the acid-treated carbon nanotube fibers were electrodeposited using cyclic voltammetry to obtain the deposited carbon nanotube fibers.
[0041] The electrolyte is a mixture of ferric chloride hydrochloric acid solution, potassium chloride solution, potassium ferricyanide solution, lactic acid solution, pyrrole solution and PBS buffer.
[0042] ③ The deposited carbon nanotube fibers were placed in PBS buffer and electro-eluted using cyclic voltammetry to obtain the MIP / CNT electrode.
[0043] II. Preparation of the reference electrode:
[0044] Ag / AgCl / yarn electrodes were prepared using yarn and Ag / AgCl conductive paste.
[0045] III. Preparation of the counter electrode:
[0046] Using a dual-potential step method, carbon nanotube fibers were plated with platinum in potassium chloroplatinate solution to obtain a Pt / conductive fiber electrode.
[0047] Specifically, the carbon nanotube fibers are produced by pulling out an array of carbon nanotubes into a film, then twisting them into oriented carbon nanotube fibers with a primary helical structure, and then twisting 5 to 50 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure; the helical angle of the oriented carbon nanotube fibers with a primary helical structure is 5° to 60°; the helical angle of the oriented carbon nanotube fibers with a secondary helical structure is 5° to 60°.
[0048] IV. Assembly of the biosensor system:
[0049] Using an Ag / AgCl / yarn electrode as the reference electrode, a Pt / conductive fiber electrode as the counter electrode, and a MIP / CNT electrode as the working electrode, the reference electrode, counter electrode, and working electrode constitute a flexible fiber biosensing system based on molecular imprinting technology.
[0050] In this specific embodiment, in steps one ① and three, the carbon nanotube array is pulled out to form a film, and then twisted into oriented carbon nanotube fibers with a primary helical structure. Subsequently, multiple such oriented carbon nanotube fibers are twisted into oriented carbon nanotube fibers with a secondary helical structure. The oriented carbon nanotube fibers can provide more modifiable sites, and the ordered pore structure is beneficial to the overall stability of the electrode, resulting in better reusability and increasing the number of times the electrode can be reused.
[0051] This specific embodiment is a three-electrode biosensor system consisting of a reference electrode, a counter electrode, and a working electrode. It is used for monitoring biomarkers in sweat through electrochemical methods. The reference electrode is an Ag / AgCl / yarn electrode, the counter electrode is a Pt / conductive fiber electrode, and the working electrode is a MIP / CNT electrode.
[0052] The MIP / CNT working electrode is prepared by co-depositing conductive polymers (such as polypyrrole PPy), redox-para-Prussian blue (PB), and template molecules (lactic acid) onto the surface of carbon nanotubes using cyclic voltammetry. The template molecules are then removed by electroelution, yielding a MIP biosensor that responds to the template molecules. Figure 2 It can be known that...
[0053] Preparation of Ag / AgCl / Yarn Reference Electrode: In this specific embodiment, a uniform Ag / AgCl conductive paste is coated on the yarn surface, giving it good conductivity and a stable potential value compared to commercially available Ag / AgCl reference electrodes. It can replace commercial reference electrodes.
[0054] Preparation of Pt / conductive fiber counter electrode: In this specific embodiment, platinum plating of CNTs is performed in potassium chloroplatinate solution using a dual potential step method. This counter electrode can replace commercial counter electrodes.
[0055] In this specific embodiment, the above-mentioned three-electrode system is woven into the fabric to obtain a wearable sensing fabric made entirely of carbon nanotube fibers.
[0056] The beneficial effects of this embodiment are:
[0057] This embodiment modifies the surface of carbon nanotube fibers with molecularly imprinted polymers (MIPs) to prepare a sensor with high sensitivity and selectivity for analytes in sweat. Simultaneously, through the principle of like charge repulsion, the surface of the sensing electrode can be cleaned in situ, allowing the electrode to be reused and exhibiting repeatability. For example, after incubation in a lactic acid solution, lactic acid molecules can specifically bind to the cavities formed by the MIPs. Lactic acid generally carries a negative charge under neutral or weakly alkaline conditions. By applying a negative voltage to the sensing electrode, the like charge repulsion removes the lactic acid molecules bound to the MIPs, allowing the sensing electrode to be reused multiple times. Furthermore, after 50 bends, the sensor current maintains good stability, remaining essentially at the initial level.
[0058] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: in step one ①, carbon nanotube fibers are placed in an H₂SO₄ solution. Using a platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and the carbon nanotube fibers as the working electrode, the carbon nanotube fibers are cyclically treated 5 to 50 times using cyclic voltammetry at a voltage of -1.5V to 1.5V and a scan rate of 0.05V / s to 0.2V / s to obtain acid-treated carbon nanotube fibers. The concentration of the H₂SO₄ solution is 0.01mol / L to 0.1mol / L. Everything else is the same as in Specific Implementation Method One.
[0059] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: in step one ②, the acid-treated carbon nanotube fibers are placed in an electrolyte, using a platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and the acid-treated carbon nanotube fibers as the working electrode. Under conditions of a voltage of -0.5V to 1.0V and a scan rate of 0.05V / s to 0.2V / s, the acid-treated carbon nanotube fibers are cyclically treated for 5 to 50 cycles using cyclic voltammetry to obtain the deposited carbon nanotube fibers. The rest is the same as in Specific Implementation Method One or Two.
[0060] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in the following ways: the volume ratio of ferric chloride hydrochloric acid solution to potassium chloride solution in step one to two is 1:(0.5-1); the volume ratio of ferric chloride hydrochloric acid solution to potassium ferricyanide solution in step one to two is 1:(0.1-1); the volume ratio of ferric chloride hydrochloric acid solution to lactic acid solution in step one to two is 1:(0.1-0.5); the volume ratio of ferric chloride hydrochloric acid solution to pyrrole solution in step one to two is 1:(0.1-2.0); and the volume ratio of ferric chloride hydrochloric acid solution to PBS buffer in step one to two is 1:(1-5). All other aspects are the same as in Specific Implementation Methods One to Three.
[0061] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the PBS buffer in step one ② is a 10×PBS buffer with a pH of 7.4; the ferric chloride hydrochloric acid solution in step one ② is prepared by mixing ferric chloride and hydrochloric acid, and the concentration of ferric chloride in the ferric chloride hydrochloric acid solution is 10 mmol / L to 100 mmol / L, and the concentration of HCl is 0.1 mol / L to 1 mol / L; the potassium chloride solution in step one ② is prepared by mixing potassium chloride and water, and the concentration of HCl in the potassium chloride solution is... The potassium concentration is 0.1 mol / L to 1 mol / L; the potassium ferricyanide solution mentioned in step 1② is prepared by mixing potassium ferricyanide and water, and the concentration of potassium ferricyanide in the solution is 10 mmol / L to 100 mmol / L; the lactic acid solution mentioned in step 1② is prepared by mixing lactic acid and water, and the concentration of lactic acid in the solution is 0.5 mol / L to 0.8 mol / L; the pyrrole solution mentioned in step 1② is prepared by mixing pyrrole and water, and the concentration of pyrrole in the solution is 0.1 mol / L to 1.0 mol / L. Other aspects are the same as in specific embodiments one to four.
[0062] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step one ③, the deposited carbon nanotube fibers are placed in PBS buffer solution. Using a platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and the deposited carbon nanotube fibers as the working electrode, the deposited carbon nanotube fibers are electro-eluted using cyclic voltammetry for 5 to 50 cycles at a voltage of -0.5V to 1.0V and a scan rate of 0.05V / s to 0.2V / s to obtain the MIP / CNT electrode. The PBS buffer solution is 10×PBS buffer with a pH of 7.4. Everything else is the same as in Specific Implementation Methods One to Five.
[0063] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the yarn mentioned in step two is cotton, nylon, or polyester; the preparation of the Ag / AgCl / yarn electrode using the yarn and Ag / AgCl conductive paste in step two is specifically carried out according to the following steps: the yarn is immersed in the Ag / AgCl conductive paste, and then the immersed yarn is rotated for 2 to 3 minutes using a motor at a speed of 2 to 5 r / min, and then dried using an infrared lamp at room temperature to obtain the Ag / AgCl / yarn electrode; the Ag / AgCl conductive paste is composed of 35 to 60 parts silver powder, 1.5 to 3 parts AgCl, 10 to 15 parts acrylic resin, and 20 to 50 parts divalent ester by mass. Everything else is the same as in Specific Implementation Methods One to Six.
[0064] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the Pt / conductive fiber electrode described in step three is prepared according to the following steps: ① Using platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and carbon nanotube fiber as the working electrode, the carbon nanotube fiber is subjected to a step treatment in a mixed solution of KCl and K2PtCl6 for 10s to 15s under a voltage of 0.2V to 1.0V, and then subjected to a step treatment in a mixed solution of KCl and K2PtCl6 for 10s to 15s under a voltage of -0.2V to -1.0V; the concentration of KCl in the mixed solution of KCl and K2PtCl6 is 0.05mol / L to 0.1mol / L, and the concentration of K2PtCl6 is 0.1mmol / L to 0.5mmol / L; ② The process is repeated 5 to 100 times according to step ①. The rest is the same as in Specific Implementation Methods One to Seven.
[0065] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the carbon nanotube array described in Step One① and Step Three is specifically performed as follows: A silicon wafer with an aluminum oxide layer and an iron layer on its surface is placed in a mixed gas, and then calcined at a temperature of 740℃ for 5 to 20 minutes, resulting in the growth of a carbon nanotube array on the silicon wafer surface; the silicon wafer with the aluminum oxide layer and iron layer on its surface is specifically a silicon wafer with an aluminum oxide layer of thickness of 20 nm to 70 nm and an iron layer of thickness of 0.5 nm to 1.5 nm sequentially coated from bottom to top; the mixed gas is specifically a mixture of argon, ethylene, and hydrogen with a flow ratio of 400:90:30. Everything else is the same as in Specific Implementation Methods One to Eight.
[0066] Specific implementation method ten, combined with Figure 4 Detailed description: This embodiment describes a detection and in-situ cleaning method for a flexible fiber biosensor system based on molecular imprinting technology, which is carried out according to the following steps:
[0067] Using an Ag / AgCl / yarn electrode as the reference electrode, a Pt / conductive fiber electrode as the counter electrode, and a MIP / CNT electrode as the working electrode, the reference electrode, counter electrode, and working electrode were all placed in a PBS buffer containing lactic acid and incubated for 1 to 5 minutes. After incubation, the it curve was measured. Then, under the conditions of -1.0V to 0V and a scan rate of 0.05V / s to 0.2V / s, the working electrode after detection was electroeluted in situ for 5 to 10 seconds using linear scanning voltammetry, thus completing the detection and cleaning method. The concentration of lactic acid in the PBS buffer containing lactic acid was 5 mmol / L to 50 mmol / L. The PBS buffer containing lactic acid was 10×PBS buffer with a pH of 7.4.
[0068] Depend on Figure 4 It is known that after incubation in lactic acid solution, lactic acid (LA) molecules can specifically bind to the cavity formed by MIP, hindering charge transport between conductive polymers and reducing the current in the it curve. Since lactic acid generally carries a negative charge under neutral or weakly alkaline conditions, by applying a negative voltage to the sensing electrode (within the range of -1.0V to 0V), the lactic acid molecules bound to MIP can be removed through the repulsion of like charges. At this point, the detected it current curve will return to its initial value, allowing the sensing electrode to be reused multiple times.
[0069] The beneficial effects of the present invention are verified using the following embodiments:
[0070] Example 1, combined with Figure 3 Detailed explanation:
[0071] A method for preparing a flexible fiber biosensing system based on molecular imprinting technology, comprising the following steps:
[0072] I. Preparation of the working electrode:
[0073] ① Carbon nanotube fibers were placed in H2SO4 solution and treated with cyclic voltammetry to obtain acid-treated carbon nanotube fibers.
[0074] Specifically, the carbon nanotube fibers are produced by pulling out an array of carbon nanotubes into a film, then twisting them into oriented carbon nanotube fibers with a primary helical structure, and then twisting 30 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure; the helical angle of the oriented carbon nanotube fibers with a primary helical structure is 18°; the helical angle of the oriented carbon nanotube fibers with a secondary helical structure is 15°.
[0075] ② The acid-treated carbon nanotube fibers were placed in an electrolyte, and the acid-treated carbon nanotube fibers were electrodeposited using cyclic voltammetry to obtain the deposited carbon nanotube fibers.
[0076] The electrolyte is a mixture of ferric chloride hydrochloric acid solution, potassium chloride solution, potassium ferricyanide solution, lactic acid solution, pyrrole solution and PBS buffer.
[0077] ③ The deposited carbon nanotube fibers were placed in PBS buffer and electro-eluted using cyclic voltammetry to obtain the MIP / CNT electrode.
[0078] II. Preparation of the reference electrode:
[0079] Ag / AgCl / cotton thread electrodes were prepared using cotton thread and Ag / AgCl conductive paste.
[0080] III. Preparation of the counter electrode:
[0081] Using a dual-potential step method, carbon nanotube fibers were plated with platinum in potassium chloroplatinate solution to obtain a Pt / conductive fiber electrode.
[0082] Specifically, the carbon nanotube fibers are produced by pulling out an array of carbon nanotubes into a film, then twisting them into oriented carbon nanotube fibers with a primary helical structure, and then twisting 30 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure; the helical angle of the oriented carbon nanotube fibers with a primary helical structure is 18°; the helical angle of the oriented carbon nanotube fibers with a secondary helical structure is 15°.
[0083] IV. Assembly of the biosensor system:
[0084] Using an Ag / AgCl / cotton thread electrode as the reference electrode, a Pt / conductive fiber electrode as the counter electrode, and a MIP / CNT electrode as the working electrode, the reference electrode, counter electrode, and working electrode constitute a flexible fiber biosensing system based on molecular imprinting technology.
[0085] In step 1①, carbon nanotube fibers are placed in H2SO4 solution. Using platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and carbon nanotube fibers as the working electrode, the carbon nanotube fibers are cyclically treated for 20 cycles using cyclic voltammetry at a voltage of -1.5V to 1.5V and a scan rate of 0.05V / s to obtain acid-treated carbon nanotube fibers. The concentration of the H2SO4 solution is 0.5mol / L.
[0086] In step 1②, the acid-treated carbon nanotube fibers are placed in an electrolyte. A platinum wire is used as the counter electrode, Ag / AgCl is used as the reference electrode, and the acid-treated carbon nanotube fibers are used as the working electrode. Under the conditions of a voltage of -0.2V to 0.9V and a scan rate of 0.05V / s, the acid-treated carbon nanotube fibers are cyclically treated for 30 cycles using cyclic voltammetry to obtain the deposited carbon nanotube fibers.
[0087] The volume ratio of ferric chloride hydrochloric acid solution to potassium chloride solution in step 1② is 1:1; the volume ratio of ferric chloride hydrochloric acid solution to potassium ferricyanide solution in step 1② is 1:1; the volume ratio of ferric chloride hydrochloric acid solution to lactic acid solution in step 1② is 1:0.1; the volume ratio of ferric chloride hydrochloric acid solution to pyrrole solution in step 1② is 1:0.4; and the volume ratio of ferric chloride hydrochloric acid solution to PBS buffer in step 1② is 1:4.
[0088] The PBS buffer mentioned in steps 1 and 2 is a 10×PBS buffer with a pH of 7.4; the ferric chloride hydrochloric acid solution mentioned in steps 1 and 2 is a mixture of ferric chloride and hydrochloric acid, and the concentration of ferric chloride in the ferric chloride hydrochloric acid solution is 80 mmol / L, and the concentration of HCl is 1 mol / L; the potassium chloride solution mentioned in steps 1 and 2 is a mixture of potassium chloride and water, and the concentration of potassium chloride in the potassium chloride solution is 1 mol / L; the potassium ferricyanide solution mentioned in steps 1 and 2 is a mixture of potassium ferricyanide and water, and the concentration of potassium ferricyanide in the potassium ferricyanide solution is 80 mol / L; the lactic acid solution mentioned in steps 1 and 2 is a mixture of lactic acid and water, and the concentration of lactic acid in the lactic acid solution is 0.5 mol / L; the pyrrole solution mentioned in steps 1 and 2 is a mixture of pyrrole and water, and the concentration of pyrrole in the pyrrole solution is 0.3 mol / L.
[0089] In step 1, the deposited carbon nanotube fibers were placed in PBS buffer. A platinum wire was used as the counter electrode, Ag / AgCl as the reference electrode, and the deposited carbon nanotube fibers were used as the working electrode. The deposited carbon nanotube fibers were electro-eluted and cyclically treated for 40 cycles using cyclic voltammetry at a voltage of -0.2V to 0.8V and a scan rate of 0.05V / s to obtain the MIP / CNT electrode. The PBS buffer was 10×PBS buffer with a pH of 7.4.
[0090] In step two, an Ag / AgCl / cotton thread electrode is prepared using cotton thread and Ag / AgCl conductive paste. Specifically, the preparation is carried out according to the following steps: the cotton thread is immersed in the Ag / AgCl conductive paste, and then the immersed cotton thread is rotated for 2 minutes at a speed of 2 r / min using a motor. Then, it is dried at room temperature using an infrared lamp to obtain the Ag / AgCl / cotton thread electrode. The Ag / AgCl conductive paste is composed of 40 parts silver powder, 2 parts AgCl, 13 parts acrylic resin and 45 parts divalent ester by mass.
[0091] The Pt / conductive fiber electrode described in step three is prepared according to the following steps: ① Using platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and carbon nanotube fiber as the working electrode, the carbon nanotube fiber is subjected to a step treatment in a mixed solution of KCl and K2PtCl6 for 10 seconds at a voltage of 0.5V to 0.8V using a dual-potential step method. Then, the carbon nanotube fiber is subjected to a step treatment in a mixed solution of KCl and K2PtCl6 for 10 seconds at a voltage of -0.5V to -0.8V. The concentration of KCl in the mixed solution of KCl and K2PtCl6 is 0.1 mol / L, and the concentration of K2PtCl6 is 0.1 mmol / L. ② The process is repeated 60 times according to step ①.
[0092] The carbon nanotube array described in Step 1① and Step 3 is specifically performed as follows: a silicon wafer with an aluminum oxide layer and an iron layer on its surface is placed in a mixed gas, and then calcined at a temperature of 740℃ for 20 minutes to grow a carbon nanotube array on the surface of the silicon wafer; the silicon wafer with an aluminum oxide layer and an iron layer on its surface is specifically a silicon wafer with an aluminum oxide layer of 30nm thickness and an iron layer of 1.1nm thickness on its surface from bottom to top; the mixed gas is specifically a mixture of argon, ethylene and hydrogen with a flow ratio of 400:90:30.
[0093] Comparative Experiment: This comparative experiment differs from Example 1 in that the addition of lactic acid solution was omitted in step 1②; the NIP / CNT electrode prepared in step 1③ was also omitted. Everything else was the same as in Example 1. After the subsequent elution process, no corresponding cavity was formed in the comparative experiment, making specific identification of the analyte impossible.
[0094] Figure 5 The image shows an electron microscope image of the carbon nanotube fiber described in step 1① of Example 1. As can be seen from the image, 30 oriented carbon nanotube fibers with a primary helical structure are twisted to form oriented carbon nanotube fibers with a secondary helical structure, with a helical angle of 15°.
[0095] Electrode response detection involved first placing the flexible fiber biosensor system based on molecular imprinting technology in blank PBS solution and measuring the initial it current value (oxidation potential peak 0.28 V, 60 s). Then, the flexible fiber biosensor system based on molecular imprinting technology was incubated in a 5 mM lactic acid solution for 2 min, followed by it measurement (oxidation potential peak 0.28 V, 60 s). Figure 6 The figure shows the response performance of the MIP / CNT electrode prepared in step 3 of Example 1. As can be seen from the figure, during the electropolymerization process, lactic acid is used as the template molecule and pyrrole is used as the functional monomer to form a molecularly imprinted polymer. After the template molecule is removed by electroelution, a molecularly imprinted cavity complementary to the lactic acid molecule is formed, which can specifically recognize the lactic acid molecule. Since polypyrrole is a conductive polymer, when lactic acid enters a specific molecularly imprinted cavity, it will hinder the electron transport between conductive polymers, and the current in the it curve will decrease. There is a current decrease of about 200 nA before and after incubation.
[0096] Concentration gradient tests were performed on lactic acid solutions of different concentrations (5 mM to 25 mM), and the oxidation potential peak value (0.28 V, 60 s) was measured. Figure 7 The graph shows the detection performance of the MIP / CNT electrode prepared in step 1③ of Example 1 for lactic acid solutions of different concentrations. Figure a represents the it current value detected in solutions of different lactic acid concentrations, and figure b represents the linear fit based on figure a. As can be seen from the figure, lactic acid molecules specifically recognize the cavities of the molecularly imprinted polymer, further hindering charge transport in the conductive polymer, thus providing a good response to different lactic acid concentrations. Furthermore, it exhibits a good linear relationship: y = 298.55 - 2.862x, where y is the current value, x is the lactic acid concentration, and the regression coefficient R0 is... 2 =0.9838, the linearity is 0.9838, close to 1, indicating good linearity, and the sensitivity is 2.862 nA / mmol;
[0097] Anti-interference tests were conducted by detecting it (oxidation potential peak 0.28 V, 60 s) in different interfering solutions (50 μm glucose solution, 5 mM urea solution, 50 μm uric acid solution, and 100 nM cortisol solution). Figure 8The graph shows the anti-interference performance of the MIP / CNT electrode prepared in step 1③ of Example 1. As can be seen from the graph, the current value of the sensor (working electrode) in 50μm glucose solution, 5mM urea solution, 50μm uric acid solution and 100nM cortisol solution did not decrease significantly compared with that in lactic acid solution (5mM), that is, there was no response, indicating that it has good anti-interference ability.
[0098] Concentration gradient tests were performed on lactic acid solutions of different concentrations (5 mM to 25 mM), and the oxidation potential peak value (it) was measured (0.28 V, 60 s). Figure 9 To compare the detection performance of the NIP / CNT electrode prepared in step 1③ of the experiment on lactic acid solutions of different concentrations; as shown in the figure, the NIP prepared without adding lactic acid template molecules during the electropolymerization process did not respond to different concentrations of lactic acid, indicating that without adding lactic acid template molecules, no molecularly imprinted cavity is formed for specific recognition, and there is no specific response to lactic acid molecules.
[0099] Example 2, combined with Figure 3 Detailed explanation: The detection and in-situ cleaning method of the flexible fiber biosensing system based on molecular imprinting technology in Example 1 is carried out according to the following steps:
[0100] Using the Ag / AgCl / cotton thread electrode prepared in Example 1 as the reference electrode, the Pt / conductive fiber electrode prepared in Example 1 as the counter electrode, and the MIP / CNT electrode prepared in Example 1 as the working electrode, the reference electrode, counter electrode, and working electrode were all placed in a PBS buffer containing lactic acid and incubated for 2 min. After incubation, the it curve (oxidation potential peak 0.28 V, 60 s) was measured. Under the conditions of voltage -1.0 V to 0 V and scan rate of 0.05 V / s, the working electrode after detection was electro-eluted for 5 s using linear scanning voltammetry, thus completing the detection and cleaning method. The concentration of lactic acid in the PBS buffer containing lactic acid was 5 mmol / L. The PBS buffer containing lactic acid was 10×PBS buffer with a pH of 7.4.
[0101] Figure 10 The diagram shows the regeneration performance of the MIP / CNT electrode in Example 2. The sensing electrode was incubated in a 10×PBS solution containing 5mM lactic acid. The decrease in the it current value was detected. Subsequently, a negative voltage was applied in situ to clean the sensing electrode, and the it current value returned to the initial level. This process can be repeated multiple times, proving that the sensing electrode can be reused. After 50 repeated tests, the current level did not decrease significantly, and the current value decreased by less than 0.2%, which is sufficient to prove that the electrode has good stability.
[0102] Figure 11The image shows the stability performance of the MIP / CNT electrode after bending in Example 2. The sensor was bent at an angle of 180°, and the current was measured every ten bends, followed by cleaning. After 50 bends, the sensor current still maintained good stability, and the current was basically the same as the initial level of the sensor.
Claims
1. A method for preparing a flexible fiber biosensing system based on molecular imprinting technology, characterized by It is done in the following steps: I. Preparation of the working electrode: ① Carbon nanotube fibers were placed in H2SO4 solution and treated with cyclic voltammetry to obtain acid-treated carbon nanotube fibers. Specifically, the carbon nanotube fibers are formed by pulling out a carbon nanotube array into a film, then twisting it into oriented carbon nanotube fibers with a primary helical structure, and then twisting 5 to 50 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure. The helical angle of the oriented carbon nanotube fiber with a primary helical structure is 5°~60°; the helical angle of the oriented carbon nanotube fiber with a secondary helical structure is 5°~60°. ② The acid-treated carbon nanotube fibers were placed in an electrolyte, and the acid-treated carbon nanotube fibers were electrodeposited using cyclic voltammetry to obtain the deposited carbon nanotube fibers. The electrolyte is a mixture of ferric chloride hydrochloric acid solution, potassium chloride solution, potassium ferricyanide solution, lactic acid solution, pyrrole solution and PBS buffer. ③ The deposited carbon nanotube fibers were placed in PBS buffer and electro-eluted using cyclic voltammetry to obtain the MIP / CNT electrode. II. Preparation of the reference electrode: Ag / AgCl / yarn electrodes were prepared using yarn and Ag / AgCl conductive paste. III. Preparation of the counter electrode: Using a dual-potential step method, carbon nanotube fibers were plated with platinum in potassium chloroplatinate solution to obtain a Pt / conductive fiber electrode. Specifically, the carbon nanotube fibers are formed by pulling out a carbon nanotube array into a film, then twisting it into oriented carbon nanotube fibers with a primary helical structure, and then twisting 5 to 50 oriented carbon nanotube fibers with a primary helical structure into oriented carbon nanotube fibers with a secondary helical structure. The helical angle of the oriented carbon nanotube fiber with a primary helical structure is 5°~60°; the helical angle of the oriented carbon nanotube fiber with a secondary helical structure is 5°~60°. IV. Assembly of the biosensor system: Using an Ag / AgCl / yarn electrode as the reference electrode, a Pt / conductive fiber electrode as the counter electrode, and a MIP / CNT electrode as the working electrode, the reference electrode, counter electrode, and working electrode constitute a flexible fiber biosensing system based on molecular imprinting technology.
2. The method for preparing a flexible fiber biosensing system based on molecular imprinting technology according to claim 1, characterized in that In step 1①, carbon nanotube fibers are placed in an H2SO4 solution. A platinum wire is used as the counter electrode, Ag / AgCl as the reference electrode, and the carbon nanotube fibers are used as the working electrode. Under the conditions of a voltage of -1.5V to 1.5V and a scan rate of 0.05V / s to 0.2V / s, the carbon nanotube fibers are cyclically treated for 5 to 50 cycles using cyclic voltammetry to obtain acid-treated carbon nanotube fibers. The concentration of the H2SO4 solution is 0.01mol / L to 0.1mol / L.
3. The method for preparing a flexible fiber biosensor system based on molecular imprinting technology according to claim 1, characterized in that In step 1②, the acid-treated carbon nanotube fibers are placed in an electrolyte. A platinum wire is used as the counter electrode, Ag / AgCl is used as the reference electrode, and the acid-treated carbon nanotube fibers are used as the working electrode. Under the conditions of a voltage of -0.5V to 1.0V and a scan rate of 0.05V / s to 0.2V / s, the acid-treated carbon nanotube fibers are cyclically treated for 5 to 50 cycles using cyclic voltammetry to obtain the deposited carbon nanotube fibers.
4. The method for preparing a flexible fiber biosensing system based on molecular imprinting technology according to claim 1, characterized in that... The volume ratio of ferric chloride hydrochloric acid solution to potassium chloride solution in step 1② is 1:(0.5~1); the volume ratio of ferric chloride hydrochloric acid solution to potassium ferricyanide solution in step 1② is 1:(0.1~1); the volume ratio of ferric chloride hydrochloric acid solution to lactic acid solution in step 1② is 1:(0.1~0.5); the volume ratio of ferric chloride hydrochloric acid solution to pyrrole solution in step 1② is 1:(0.1~2.0); the volume ratio of ferric chloride hydrochloric acid solution to PBS buffer in step 1② is 1:(1~5).
5. The method for preparing a flexible fiber biosensing system based on molecular imprinting technology according to claim 4, characterized in that... The PBS buffer mentioned in step 1② is a 10×PBS buffer with a pH of 7.4; the ferric chloride hydrochloric acid solution mentioned in step 1② is prepared by mixing ferric chloride and hydrochloric acid, and the concentration of ferric chloride in the ferric chloride hydrochloric acid solution is 10 mmol / L~100 mmol / L, and the concentration of HCl is 0.1 mol / L~1 mol / L; the potassium chloride solution mentioned in step 1② is prepared by mixing potassium chloride and water, and the concentration of potassium chloride in the potassium chloride solution is 0.1 mol / L~1 mol / L. The potassium ferricyanide solution mentioned in step 1② is prepared by mixing potassium ferricyanide with water, and the concentration of potassium ferricyanide in the potassium ferricyanide solution is 10 mmol / L~100 mmol / L; the lactic acid solution mentioned in step 1② is prepared by mixing lactic acid with water, and the concentration of lactic acid in the lactic acid solution is 0.5 mol / L~0.8 mol / L; the pyrrole solution mentioned in step 1② is prepared by mixing pyrrole with water, and the concentration of pyrrole in the pyrrole solution is 0.1 mol / L~1.0 mol / L.
6. The method for preparing a flexible fiber biosensing system based on molecular imprinting technology according to claim 1, characterized in that... In step 1, the deposited carbon nanotube fibers were placed in PBS buffer. A platinum wire was used as the counter electrode, Ag / AgCl as the reference electrode, and the deposited carbon nanotube fibers as the working electrode. The deposited carbon nanotube fibers were electro-eluted and cyclically treated for 5 to 50 cycles using cyclic voltammetry at a voltage of -0.5V to 1.0V and a scan rate of 0.05V / s to 0.2V / s to obtain the MIP / CNT electrode. The PBS buffer was 10×PBS buffer with a pH of 7.
4.
7. The method for preparing a flexible fiber biosensing system based on molecular imprinting technology according to claim 1, characterized in that... The yarn mentioned in step two is cotton, nylon, or polyester. The preparation of the Ag / AgCl / yarn electrode using the yarn and Ag / AgCl conductive paste in step two is specifically carried out according to the following steps: the yarn is immersed in the Ag / AgCl conductive paste, and then the immersed yarn is rotated for 2-3 minutes using a motor at a speed of 2-5 r / min. It is then dried using an infrared lamp at room temperature to obtain the Ag / AgCl / yarn electrode. The Ag / AgCl conductive paste is composed of 35-60 parts silver powder, 1.5-3 parts AgCl, 10-15 parts acrylic resin, and 20-50 parts divalent ester by mass.
8. The method for preparing a flexible fiber biosensing system based on molecular imprinting technology according to claim 1, characterized in that... The Pt / conductive fiber electrode described in step three is prepared according to the following steps: ① Using platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and carbon nanotube fiber as the working electrode, the carbon nanotube fiber is subjected to a step treatment in a mixed solution of KCl and K2PtCl6 for 10s to 15s under a voltage of 0.2V to 1.0V, and then subjected to a step treatment in a mixed solution of KCl and K2PtCl6 for 10s to 15s under a voltage of -0.2V to -1.0V; the concentration of KCl in the mixed solution of KCl and K2PtCl6 is 0.05mol / L to 0.1mol / L, and the concentration of K2PtCl6 is 0.1mmol / L to 0.5mmol / L; ② The process is repeated 5 to 100 times according to step ①.
9. The method for preparing a flexible fiber biosensing system based on molecular imprinting technology according to claim 1, characterized in that... The carbon nanotube array described in Step 1① and Step 3 is specifically performed as follows: a silicon wafer with an aluminum oxide layer and an iron layer on its surface is placed in a mixed gas, and then calcined at a temperature of 740℃ for 5 min to 20 min to grow a carbon nanotube array on the surface of the silicon wafer; the silicon wafer with an aluminum oxide layer and an iron layer on its surface is specifically an aluminum oxide layer with a thickness of 20 nm to 70 nm and an iron layer with a thickness of 0.5 nm to 1.5 nm, which are sequentially coated from bottom to top on the surface of the silicon wafer; the mixed gas is specifically a mixture of argon, ethylene and hydrogen with a flow ratio of 400:90:
30.
10. A method for detection and in-situ cleaning of a flexible fiber biosensing system based on molecular imprinting technology prepared by the method described in claim 1, characterized in that... It is done in the following steps: Using an Ag / AgCl / yarn electrode as the reference electrode, a Pt / conductive fiber electrode as the counter electrode, and a MIP / CNT electrode as the working electrode, the reference electrode, counter electrode, and working electrode were all placed in a PBS buffer containing lactic acid and incubated for 1 to 5 minutes. After incubation, the it curve was measured. Then, under the conditions of -1.0V to 0V and a scan rate of 0.05V / s to 0.2V / s, the working electrode after detection was electroeluted in situ for 5 to 10 seconds using linear scanning voltammetry, thus completing the detection and cleaning method. The concentration of lactic acid in the PBS buffer containing lactic acid was 5 mmol / L to 50 mmol / L. The PBS buffer containing lactic acid was 10×PBS buffer with a pH of 7.4.