High-stability reversible deformation carbon nanotube fiber sensor and device and method thereof

Abstract

The invention discloses a high-stability reversible deformation carbon nanotube fiber sensor, and a device and a method thereof, and relates to the technical field of electrochemical biosensors. According to the sensor, fusiform carbon nanotube fibers are adopted as a sensing base body, sensitive materials are embedded into the fibers in the expansion state of the fusiform carbon nanotube fibers to form a stable sensitive layer, then the stable sensitive layer is recovered into a slender structure through screwing, and closed protection and minimally invasive implantation of the sensitive layer are achieved. The invention also provides a multi-parameter electrochemical detection device, which can realize in-vivo synchronous detection of various physiological indexes such as hydrogen peroxide, superoxide anions and glucose, and is suitable for continuous monitoring and early warning of a complex disease process. The device is novel in structure and high in function integration degree, has good mechanical protection performance and biological compatibility, is particularly suitable for multi-index in-vivo continuous monitoring, and has wide application prospects in the scenes of chronic disease early warning, postoperative monitoring, metabolic disorder evaluation and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrochemical biosensors, and particularly relates to a high-stability reversible deformation carbon nanotube fiber sensor and a device and method thereof. BACKGROUND

[0002] In recent years, in vivo continuous monitoring technology has gradually become an important tool for dynamic management and precise treatment of diseases, and electrochemical biosensors are widely used in real-time monitoring of key physiological indicators such as active oxygen (such as H2O2, O2 ·- ) and metabolites (such as Glu). Common implantable electrochemical sensors mainly use rigid electrodes (such as metal wires or microneedles) or flexible electrodes (such as carbon nanotube fibers) as substrates, each with advantages and disadvantages. The rigid electrode has the advantages of stable structure, excellent conductivity and mature processing technology, but the difference between its mechanical properties and biological tissues is large, which easily causes tissue irritation and rejection reaction, and is not conducive to long-term implantation. In comparison, the flexible electrode has good biocompatibility and adaptability, and the new flexible material represented by the carbon nanotube fiber is concerned due to its softness and braiding property. However, the mechanical protection ability of the existing flexible electrode is limited, and in long-term in vivo dynamic monitoring, the sensitive layer is easily peeled off, the enzyme is inactivated, and the signal drifts, which seriously affects the detection stability and life of the sensor.

[0003] The commonly used material modification methods at present mainly include electrodeposition, drop coating or physical adsorption, etc. to fix the electrocatalytic materials and enzyme molecules on the surface of the sensor. Such surface modification strategies have the following problems:

[0004] 1. The sensitive layer is directly exposed to the external environment, which is easily affected by the in vivo shear force, liquid flow disturbance and tissue contact, leading to membrane peeling, recognition element inactivation, and thus reducing the reliability and stability of the sensor;

[0005] 2. Although the polymer coating can enhance the film fixation to some extent, it usually sacrifices the mass transfer efficiency and increases the complexity of sensor preparation;

[0006] 3. The limited effective surface area of the electrode limits the loading amount of the sensitive material, which further affects the detection sensitivity;

[0007] 4. In order to improve the modification efficiency, the size of the electrode or the introduction of porous / expansion structure is often needed, but this will increase the implant volume and aggravate the tissue trauma, which is not conducive to minimally invasive implantation;

[0008] 5. The sensor integration design required for multi-index collaborative detection still faces challenges such as low space utilization and packaging difficulty.

[0009] In summary, the existing implantable electrochemical sensor still has significant deficiencies in the structural stability, modification efficiency, minimally invasive and integration ability of the sensitive layer, which is difficult to meet the actual needs of multi-parameter long-term in-vivo monitoring. Therefore, it is urgent to develop a new type of carbon nanotube fiber sensor structure, which can provide an expanded state during the preparation stage to realize efficient internal modification of the sensitive material, and after the modification is completed, the structure is restored to a slender form, thereby sealing and protecting the sensitive layer and reducing the implantation trauma, realizing the structural conversion ability of "high load - strong protection - minimally invasive" compatibility. At the same time, the structure should have integrability, support multi-index sensor collaborative packaging and in-vivo application, and provide a reliable solution for biomedical detection. SUMMARY

[0010] The purpose of the present application is to overcome the defects in the prior art, aiming at the problems of poor stability of the sensitive layer, limited modification load, insufficient structural protection and poor minimally invasive implantation adaptability of the existing implantable electrochemical sensor, and providing a high-stable reversible deformation carbon nanotube fiber sensor and its device and method. The sensor of the present application has a sensor structure with high load modification ability, sensitive layer protection ability and minimally invasive implantation characteristics, which expands the application potential of carbon nanotube fibers in in-vivo multi-parameter long-term stable electrochemical monitoring.

[0011] The specific technical solutions adopted by the present application are as follows:

[0012] In a first aspect, the present application provides a preparation method of a high-stable reversible deformation carbon nanotube fiber sensor, which is as follows:

[0013] The local expansion area in the middle of the intrinsic carbon nanotube fiber is expanded, so that the local expansion area has reversible deformation ability and presents a spindle shape, and the carbon nanotube network originally buried in the intrinsic carbon nanotube fiber is fully exposed; the sensitive material is modified in the exposed carbon nanotube network to form a sensitive layer, and the sensitive material can realize high-sensitivity electrochemical detection of the target marker; then the intrinsic carbon nanotube fiber is screwed, so that the local expansion area restores to a slender structure, realizing the closed protection of the sensitive layer and facilitating subsequent minimally invasive implantation.

[0014] As a preferred, the maximum diameter of the expanded local expansion area is 30 times or more than the diameter of the rest of the intrinsic carbon nanotube fiber, and the diameter of the local expansion area after screwing is less than 10% of the diameter during expansion.

[0015] As a preferred, the expansion treatment method includes electrochemical expansion method, bubble-induced reconstruction method, mechanical stretching, electric field induction, and heat treatment.

[0016] As a preferred, a protective layer is coated outside the local expansion area after screwing; the protective layer material includes polyurethane, polyvinyl chloride, chitosan and zwitterionic polymer.

[0017] Preferably, the sensitive layer is obtained by one of the following three ways:

[0018] S1: the sensitive material is a biological recognition element and an electrocatalytic material; the electrocatalytic material is first modified inside the carbon nanotube network, and then the biological recognition element is modified to catalytically decompose the product of the biological recognition element reaction and convert it into an electrical signal that can be directly measured;

[0019] the biological recognition element is glucose oxidase or lactate oxidase;

[0020] S2: the sensitive material is superoxide dismutase, a cysteine layer and an electrocatalytic material; the electrocatalytic material, cysteine and superoxide dismutase are sequentially modified inside the carbon nanotube network; the cysteine is fixed by the electrocatalytic material, and then the superoxide dismutase is connected and fixed by the cysteine; a direct electron transfer effect of the superoxide dismutase is used to form an electrical signal that can be directly measured;

[0021] S3: the sensitive material is an electrocatalytic material that has an enzyme-like property and can catalyze the decomposition of hydrogen peroxide; the electrocatalytic material specifically catalyzes H2O2 and realizes electron transfer to form an electrical signal that can be directly measured.

[0022] Further, the electrocatalytic material is a metal nanoparticle or an inorganic compound, including gold, platinum and Prussian blue; the electrocatalytic material is modified inside the carbon nanotube network by electrodeposition, physical adsorption or covalent bonding.

[0023] Further, in S2, the cysteine is self-assembled into a monolayer of cysteine by direct immersion.

[0024] Further, the biological recognition element and the superoxide dismutase are both modified inside the carbon nanotube network by physical adsorption, covalent bonding, electro-polymerization or chemical cross-linking.

[0025] In a second aspect, the present application provides a high-stability reversible deformation carbon nanotube fiber sensor prepared by the preparation method of any one of the first aspect.

[0026] In a third aspect, the present application provides a multi-parameter electrochemical detection device, which comprises at least three high-stability reversible deformation carbon nanotube fiber sensors as described in the second aspect, and further comprises a reference electrode fiber and a counter electrode fiber; all the fibers are packaged into an integrated flexible implantable sensing assembly.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] 1) High sensitivity: The local expansion structure of the spindle-shaped carbon nanotube fiber in the present application significantly improves the accessibility of the sensitive material into the carbon nanotube network inside the fiber, so that the sensitive material can be more fully embedded inside the fiber. By constructing such an embedded sensitive layer structure, the effective surface area that can be modified is effectively increased, the material loading efficiency is improved, and a structural basis for high-sensitivity electrochemical detection is provided.

[0029] 2) Enhanced stability: In the present application, the sensitive layer is fixed inside the carbon nanotube fiber by embedding, avoiding the problem of film peeling and signal drift caused by shear force, fluid scouring or tissue contact in the implantation process of traditional surface modification structure, thereby improving the short-term operation stability and response consistency in complex in vivo environment.

[0030] 3) Excellent durability: Since the sensitive layer is deeply embedded in the dense carbon nanotube network structure, it can effectively prevent the sensitive material (including biological recognition elements and electrocatalytic materials, etc.) from being inactivated, desorbed or detached due to long-term contact with biological fluids. This internal stable structure ensures that the sensing performance remains stable under continuous monitoring conditions for several days or even weeks, significantly extending the service life of the sensor and providing good long-term durability.

[0031] 4) Strong minimally invasive implantation ability: The present application restores the fiber to its original unexpanded state by tightening it, significantly reducing the outer diameter of the sensor (the diameter of the locally expanded region after tightening is less than 10% of the diameter of the locally expanded region before tightening), which can reach the level of suture fineness. This form helps to reduce tissue puncture resistance and damage risk, improve the convenience and tissue compatibility of implantation operation, and meet the needs of chronic implantation and minimally invasive application.

[0032] 5) Strong sensing integration: The structural units proposed in the present application can construct sensing fibers with different functions (such as Glu, H2O2, O2 ·- , etc.) according to the detection requirements, and integrate multiple functional fibers with reference electrodes and counter electrodes into the same platform through flexible packaging technology, to construct a multi-parameter synchronous detection system with compact structure, independent function and no signal interference, and to improve the system integration and monitoring throughput.

[0033] 6) Wide application expansion: The sensing system is suitable for various scenarios that require in vivo continuous monitoring, such as active oxygen fluctuation tracking in liver ischemia-reperfusion (I / R) model, dynamic evaluation of abnormal glucose metabolism, real-time feedback of tissue microenvironment changes during postoperative monitoring, etc. Its wide adaptability provides a highly universal sensing platform solution for basic research and clinical application. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0035] Figure 1 Optical image of the spindle-shaped carbon nanotube fiber prepared in the embodiment 1 of the present application;

[0036] Figure 2 Scanning electron microscope image of the carbon nanotube fiber in the typical embodiment of the present application. Wherein, figure a and figure b are the morphology and local enlarged image of the intrinsic carbon nanotube fiber respectively; figure c and figure d are the surface morphology and local enlarged image of the spindle-shaped carbon nanotube fiber respectively;

[0037] Figure 3 Optical image of the construction and reversible deformation process of the spindle-shaped carbon nanotube fiber in the typical embodiment of the present application;

[0038] Figure 4 Modification process and detection principle schematic diagram of the spindle-shaped carbon nanotube fiber glucose sensor in the embodiment 2 of the present application;

[0039] Figure 5 Difference comparison of the intrinsic carbon nanotube fiber and the spindle-shaped carbon nanotube fiber after modification in the embodiment 2 and the embodiment 7 of the present application. Wherein, figure a is the modification process schematic diagram of the intrinsic carbon nanotube fiber and the spindle-shaped carbon nanotube fiber; figure b and c are the scanning electron microscope image of the surface of the intrinsic carbon nanotube fiber glucose sensor and the scanning electron microscope image of the internal fiber after destroying the surface sensitive layer respectively; figure d and e are the scanning electron microscope image of the internal carbon nanotube network of the spindle-shaped carbon nanotube fiber before modifying the sensitive layer and after modifying the sensitive layer respectively;

[0040] Figure 6 Instantaneous current method detection curve of the spindle-shaped carbon nanotube fiber glucose sensor constructed in the embodiment 2 of the present application;

[0041] Figure 7 Modification process and detection principle schematic diagram of the spindle-shaped carbon nanotube fiber hydrogen peroxide sensor in the embodiment 3 of the present application;

[0042] Figure 8 Instantaneous current method detection curve of the intrinsic carbon nanotube fiber hydrogen peroxide sensor and the spindle-shaped carbon nanotube fiber hydrogen peroxide sensor in the embodiment 3 and the embodiment 7 of the present application;

[0043] Figure 9This is a schematic diagram illustrating the modification process and detection principle of the spindle-shaped carbon nanotube fiber superoxide anion sensor in Example 4 of the present invention.

[0044] Figure 10 The instantaneous current method detection curves for comparing the intrinsic carbon nanotube fiber superoxide anion sensor and the spindle-shaped carbon nanotube fiber hydrogen peroxide sensor in Examples 4 and 7 of this invention are shown.

[0045] Figure 11 This is a verification of the reversible deformation of the spindle-shaped carbon nanotube fiber sensor in Example 5 of the present invention. Figure a shows a comparison of the sensitivity curves of the spindle-shaped carbon nanotube fiber hydrogen peroxide sensor before and after tightening; Figure b shows a comparison of the sensitivity curves of the spindle-shaped carbon nanotube fiber superoxide anion sensor before and after tightening.

[0046] Figure 12 This is a schematic diagram of the integration of a multi-parameter minimally invasive implantable sensor in Embodiment 6 of the present invention;

[0047] Figure 13 This is a schematic diagram of the implantation of a multi-parameter fiber sensor using a suture needle in Embodiment 6 of the present invention;

[0048] Figure 14 In Example 7 of this invention, the stability of the intrinsic carbon nanotube fiber sensor and the spindle-shaped carbon nanotube fiber sensor were compared under simulated cleaning conditions using a vortex apparatus.

[0049] Figure 15 This is a schematic diagram of the fiber sensor fabrication method of the present invention;

[0050] The attached diagram is labeled as follows: 1—Implanted part; 2—Connection to the back-end detection equipment; 3—Medical heat shrink tubing; 4—Reference electrode; 5—Counter electrode; 6—Glucose sensing fiber; 7—Hydrogen peroxide sensing fiber; 8—Superoxide anion sensing fiber; 9—Multi-parameter electrochemical detection device; 10—Medical implant needle. Detailed Implementation

[0051] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0052] It should be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0053] like Figure 15 The diagram shown is a schematic flow chart of a method for fabricating a highly stable reversible deformable carbon nanotube fiber sensor provided by the present invention. The fabrication method specifically includes the following steps:

[0054] The local expansion area in the middle of the intrinsic carbon nanotube fiber is expanded, so that the local expansion area has reversible deformation ability and presents a spindle shape, and the carbon nanotube network originally buried in the intrinsic carbon nanotube fiber is fully exposed; a sensitive material is modified in the exposed carbon nanotube network to form a sensitive layer with sufficient loading and stable interface; wherein the sensitive material can realize high-sensitivity electrochemical detection of target markers; then the intrinsic carbon nanotube fiber is screwed, so that the local expansion area returns to a slender structure, realizing closed protection of the sensitive layer and facilitating subsequent minimally invasive implantation.

[0055] The above-mentioned "expansion-modification-screw" process not only enhances the loading capacity of the sensitive material, but also realizes structural coating, effectively improving the construction efficiency, functional integration and structural stability of the sensor, and providing a new path for in-vivo high-performance sensing.

[0056] As a preferred embodiment of the present application, the above-mentioned preparation method of the present application is to modify the sensitive material (including electrocatalytic material and biological recognition element, etc.) in the expanded state of the local expansion area of the intrinsic carbon nanotube fiber, and the maximum diameter of the expanded local expansion area should be 30 times or more than the diameter of the rest of the intrinsic carbon nanotube fiber; then the local expansion area of the fiber is screwed, and the diameter of the screwed local expansion area is less than 10% of the diameter when it is expanded, and the size and shape are suitable for minimally invasive implantation in vivo.

[0057] As a preferred embodiment of the present application, the sensitive layer can be closed in the fiber after the local expansion area of the fiber is screwed. In order to enhance the sealing performance, a protective layer can be coated outside the screwed local expansion area. The materials of the protective layer include but are not limited to polyurethane, polyvinyl chloride, chitosan and zwitterionic polymer.

[0058] The present application constructs the embedding and structural protection mechanism in the sensitive layer, avoids the problems such as film peeling and enzyme deactivation caused by exposing the sensitive material to the outside world in traditional electrodes, and significantly improves the stability and reliability of the sensor in dynamic in-vivo environment.

[0059] As a preferred embodiment of the present application, the intrinsic carbon nanotube fiber can be expanded by a one-step electrochemical expansion method, a bubble-induced restructuring method or other mechanical stretching, electric field induction, heat treatment, etc. disclosed in the prior art to obtain a "spindle-shaped carbon nanotube fiber", i.e. the "spindle-shaped carbon nanotube fiber" is not limited to its specific construction method. The core of the present application is to realize the reversible deformation ability of the fiber and the structural characteristics of the internal expansion space of the spindle-shaped structure, and then realize the internal loading and stable packaging of the sensitive material. Therefore, as long as the structure and function requirements described in the present application are met, the spindle-shaped structure of the fiber is obtained, which belongs to the protection scope of the present application. For example, the method provided in the patent No. ZL 202211491118.X, the invention name of a spindle-shaped carbon nanotube fiber and its preparation method can be used to expand the local expansion area in the middle of the fiber.

[0060] The present application utilizes the reversible deformation ability of the fiber to realize efficient sensitive layer construction, and through the tightening action, the sensor is restored to the original micron-scale slender structure, so that the sensitive layer is not directly exposed to the interface friction environment, and the stability is enhanced. At the same time, the small diameter can minimize the implant size, reduce the risk of tissue damage, and improve its application adaptability in minimally invasive long-term implantation.

[0061] As a preferred embodiment of the present application, the sensitive layer is obtained by modifying the sensitive material in one of the following three ways:

[0062] S1: The sensitive material can be a biological recognition element and an electrocatalytic material. In this case, the electrocatalytic material needs to be modified inside the carbon nanotube network first, and then the biological recognition element is modified to catalytically decompose the product of the biological recognition element reaction and convert it into an electrical signal that can be directly measured.

[0063] Among them, the biological recognition element is glucose oxidase or lactate oxidase, etc.

[0064] This is because the above enzyme molecules can specifically bind to the target marker to be detected and catalyze the redox reaction. However, enzyme molecules often cannot produce an electrical signal that can be directly measured by the electrode base, so an electrocatalytic material is needed to catalytically decompose the product of the enzyme reaction to convert it into an electrical signal that can be directly measured, thereby realizing the conversion of the biological recognition event to the electrical signal.

[0065] In actual use, the electrocatalytic material can be metal nanoparticles or inorganic compounds, including but not limited to gold, platinum, Prussian blue. The electrocatalytic material can be modified inside the carbon nanotube network by electrodeposition, physical adsorption, covalent bonding, etc.

[0066] In actual use, the biological recognition element can be modified inside the carbon nanotube network by physical adsorption, covalent connection, electro-polymerization or chemical cross-linking.

[0067] S2: The sensitive material can be superoxide dismutase, cysteine layer and electro-catalytic material. In this case, the electro-catalytic material, cysteine and superoxide dismutase need to be modified inside the carbon nanotube network in sequence, the cysteine is fixed by the electro-catalytic material, and then the superoxide dismutase is connected and fixed by the cysteine, and the direct electron transfer of the superoxide dismutase forms a direct measurement of the electrical signal.

[0068] In actual use, the electro-catalytic material can be metal nanoparticles or inorganic compounds, including but not limited to gold, platinum and Prussian blue. The electro-catalytic material can be modified inside the carbon nanotube network by electrodeposition, physical adsorption, covalent bonding and the like.

[0069] In actual use, the superoxide dismutase can be modified inside the carbon nanotube network by physical adsorption, covalent connection, electro-polymerization or chemical cross-linking.

[0070] In actual use, the cysteine can be self-assembled into a cysteine monolayer by direct immersion. Taking gold nanoparticles as an example of the electro-catalytic material, the thiol group of the cysteine can form an Au-S bond with the gold nanoparticles in the self-assembly process, so that the cysteine is fixed on the gold nanoparticles.

[0071] S3: The sensitive material can be an electro-catalytic material with enzyme-like properties and capable of catalyzing the decomposition of hydrogen peroxide. The electro-catalytic material specifically catalyzes H2O2 and realizes electron transfer to form a direct measurement of the electrical signal.

[0072] In actual use, the electro-catalytic material can be metal nanoparticles or inorganic compounds, including but not limited to gold, platinum and Prussian blue. The electro-catalytic material can be modified inside the carbon nanotube network by electrodeposition, physical adsorption, covalent bonding and the like.

[0073] The sensor obtained by the above preparation method adopts a carbon nanotube fiber with a spindle structure as a carrier, a sensitive material is embedded inside to construct a high-efficiency sensitive layer, and high-sensitivity and long-term stable detection of key biomolecules such as active oxygen (such as hydrogen peroxide H2O2, superoxide anion O2 ·- ) and metabolites (such as glucose Glu) can be realized. The fiber has reversible deformation capability, so that it remains in an expanded state during the modification of the sensitive layer to improve the modification efficiency, and is restored to a slender state after modification to realize the structural closure and protection of the sensitive layer, and also helps to reduce the implant size, reduce tissue damage, and improve the biological adaptability and stability in vivo.

[0074] The present application also provides a multi-parameter electrochemical detection device, which comprises at least three high-stable reversible deformation carbon nanotube fibers of the above-mentioned basic application. The sensitive materials of the three fibers can be respectively an electrocatalytic material capable of catalyzing the decomposition of hydrogen peroxide, a superoxide dismutase, a cysteine layer and an electrocatalytic material, and a glucose oxidase and an electrocatalytic material, so as to be respectively used for detecting hydrogen peroxide, superoxide anion and glucose. In addition, the device further comprises a reference electrode fiber and a counter electrode fiber, and all the fibers are packaged into an integrated flexible implantable sensing assembly. In order to facilitate use, the signals of the sensing fibers can be synchronously measured by connecting an electrochemical workstation or an integrated circuit board, and can be wirelessly transmitted to an external data analysis terminal in real time.

[0075] That is, the present application further realizes a flexible and miniaturized multi-parameter electrochemical detection device by integrating a plurality of functional sensing fibers (for example, for detecting H2O2, O2 ·- , Glu) with a reference electrode fiber and a counter electrode fiber, realizes synchronous detection of multiple physiological indicators, and is particularly suitable for in vivo continuous monitoring and dynamic analysis of disease processes, and provides a reliable means for in vivo real-time monitoring of complex pathological processes such as liver reperfusion, inflammatory response and metabolic abnormalities.

[0076] The preparation method of the present application and the application and effect of the obtained sensor will be specifically described below through examples.

[0077] Example 1

[0078] In this example, a spindle-shaped carbon nanotube fiber is prepared, which aims to illustrate a method for obtaining a spindle-shaped carbon nanotube fiber structure. The method is derived from the published electrochemical-induced structural expansion strategy and is only used to illustrate the implementation path of the fiber structure described in the present application, and does not constitute the protection content of the present application.

[0079] A commercial carbon nanotube fiber (twisted, diameter about 60 μm) is selected and cut to a length of about 2 cm. One end of the fiber is bonded to a copper lead using conductive silver paste to achieve electrical connection and simple packaging, and the length of the front end of the carbon nanotube fiber is maintained at 1.5 cm. The fiber is vertically fixed on a conductive clamp, and is prepared for structural reconstruction under electrochemical reduction conditions.

[0080] In an open glass container, 10 mL of 1 M H2SO4 solution was added, and a two-electrode system was used: a platinum electrode as the counter electrode (connected to the positive pole of the power supply), and a carbon nanotube fiber connected with a copper wire as the working electrode (connected to the negative pole of the power supply). Half of the fiber was immersed in the electrolyte, and the other half was suspended in the air. A voltage was applied to the working electrode (adjustable in the range of -2 V to -7 V), and local expansion of the carbon nanotube fiber occurred at the liquid-air interface, forming a stable spindle-shaped structure (the diameter of the expanded region increased to about 1.8 mm, about 30 times the diameter of the intrinsic fiber), as shown in FIG. 1. Figure 1 The expanded spindle-shaped carbon nanotube fiber had a significantly looser carbon nanotube network structure, as shown in the electron micrograph. Figure 2 This provided a reliable microscale channel for the modified material to enter and be fixed inside the fiber. As shown in FIG. 2, the spindle-shaped structure had a reversible deformation, and could be screwed back to the original fiber state under the action of an external force. Figure 3

[0081] It should be noted that the construction of the spindle-shaped structure is not limited to the above-mentioned electrochemical induction method, and can also be obtained by other methods such as mechanical stretching, electrothermal treatment, laser heating, and bubble-assisted reconstruction, which will not be described here.

[0082] Example 2

[0083] In this example, a spindle-shaped carbon nanotube fiber glucose sensor was prepared. On the basis of the spindle-shaped carbon nanotube fiber prepared in Example 1, the glucose sensor was prepared by layer-by-layer material modification. The modified layers of the fiber and the detection principle are shown in FIG. 3. Figure 4 As can be seen from the figure, the spindle-shaped carbon nanotube fiber is used as a conductive substrate, the inside of the fiber is composed of a dense interwoven carbon nanotube network, and has excellent conductivity and flexibility. A Prussian blue (PB) electrocatalytic layer, a poly-o-phenylenediamine-glucose oxidase (PoPD-GOx) functional layer, and a polyurethane (PU) diffusion control layer were successively modified in the local expansion region of the carbon nanotube fiber, so that the sensitive layer was stably fixed in the carbon nanotube network inside the fiber. PB, as an artificial peroxidase, can efficiently catalyze the reduction reaction of H2O2 at a low potential, significantly reducing the detection background current. GOx catalyzes the oxidation of glucose to generate gluconic acid and H2O2, and the generated H2O2 is reduced in the PB layer, releasing electrons to the carbon nanotube fiber and generating a current signal. The signal strength is proportional to the glucose concentration, thereby realizing sensitive detection of glucose. The outer PU film can regulate the substrate permeation rate, improving the detection range and stability of the sensor.

[0084] ​(1) Construction of electrocatalytic layer: Prussian blue (PB) electrocatalytic layer was constructed on the spindle-shaped carbon nanotube fiber by cyclic voltammetry (CV). A three-electrode system was used: a commercial Ag / AgCl electrode as the reference electrode, a commercial Pt wire electrode as the counter electrode, and the spindle-shaped carbon nanotube fiber as the working electrode. The deposition conditions were as follows: 16 cycles of deposition at a potential range of -0.1 V to 0.4 V in a PB plating solution containing 2.5 mM K3[Fe(CN)6], 2.5 mM FeCl3, 0.1 M KCl, and 0.1 M HCl, to form a well-dispersed PB layer. To improve the stability of the PB film, the PB layer-modified spindle-shaped carbon nanotube fiber was placed in a solution of 0.1 M KCl and 0.1 M HCl and scanned several cycles at a potential range of -0.5 V to 0.35 V.

[0085] (2) Construction of poly-o-phenylenediamine-enzyme composite sensitive layer: The method of co-polymerization of o-phenylenediamine (oPD) and glucose oxidase (GOx) was selected to achieve efficient and stable immobilization of GOx. During the polymerization process, poly-o-phenylenediamine (PoPD) can co-embed or wrap the enzyme into the polymer network, providing a mild and efficient immobilization method. The fiber was immersed in an acetic acid-sodium acetate buffer containing 30 mg / mL GOx and 5 mM oPD, and a uniform PoPD-GOx composite sensitive layer was formed by electro-polymerization at a voltage of +0.6 V for 25 min. Under scanning electron microscopy, it can be seen that each carbon nanotube in the spindle-shaped local interior Figure 5 d) was uniformly modified with an electrocatalytic layer and a PoPD-GOx composite sensitive layer Figure 5 e) After modification, the fiber was manually rotated at both ends to restore it to its original fiber state before the spindle shape changed, and the sensitive layer was sealed inside the fiber.

[0086] (3) Construction of chitosan protective layer: To reduce the impact of subsequent limited diffusion layer coating on the activity of GOx, the fiber was coated once in a 1% chitosan solution to obtain a chitosan protective layer before coating the limited diffusion layer.

[0087] (4) Construction of limited diffusion layer: Since the concentration of glucose in the body fluid is usually high, direct action on the enzyme layer can easily cause rapid response, signal overload, or enzyme saturation; the polyurethane (PU) layer is a semi-permeable membrane that has a certain blocking effect on glucose, which can reduce the diffusion rate, slow down the substrate into the enzyme layer, make the reaction more linear, and expand the linear detection range. The fiber was coated once in 4% PU and dried to obtain the outermost limited diffusion layer.

[0088] As shown in Figure 6 , the obtained glucose sensor was used to detect glucose in the range of 0-12 mM, showing good sensitivity and linearity (sensitivity: 611 nA / mM, R 2 = 0.99384).

[0089] Example 3

[0090] This embodiment fabricates a spindle-shaped carbon nanotube fiber H2O2 sensor. Based on the spindle-shaped carbon nanotube fiber obtained in Example 1, layer-by-layer material modification is performed to achieve the fabrication of the H2O2 sensor. The fiber modification layers and detection principle are as follows: Figure 7 As shown in the figure, the electrode uses spindle-shaped carbon nanotube fibers as the conductive substrate material, and a PB functional layer is modified on its surface by electrochemical deposition. The constructed PB / CNT composite electrode exhibits good electrocatalytic reduction activity for H2O2 at low potentials (e.g., -0.1V). During the detection process, H2O2 undergoes a reduction reaction under the catalytic action of PB on the electrode surface, generating OH-. - Simultaneously, PB transforms from its oxidized state (PB_ox) to its reduced state (PB_red), and subsequently undergoes a cyclic regeneration process through electron transfer. This redox process generates a current signal on the working electrode, the intensity of which is proportional to the H2O2 concentration, thereby enabling sensitive detection of H2O2.

[0091] PB was electrodeposited using the same method as in Example 2 and used as the electrocatalytic active site for hydrogen peroxide. No enzyme immobilization was required; H2O2 detection was performed directly.

[0092] The fiber sensor exhibited good sensitivity and linearity when tested with H2O2 solutions of different concentrations (0–100 μM) at -0.1 V (sensitivity: 106 nA / μM, R0). 2 =0.99814), such as Figure 8 As shown.

[0093] Example 4

[0094] This embodiment prepared a spindle-shaped carbon nanotube fiber O2. ·- The sensor is based on the spindle-shaped carbon nanotube fibers prepared in Example 1, through layer-by-layer material modification to achieve O2. ·- Sensor fabrication. The fiber modification layer and detection principle are as follows: Figure 9 As shown in the figure, the construction method involves sequentially modifying the surface of carbon nanotube fibers with gold nanoparticles, self-assembling a cysteine ​​functional layer, and immobilizing superoxide dismutase (SOD) to form a layered biorecognition interface. The gold nanoparticles enhance electrode conductivity and provide anchoring sites for functional groups, while the self-assembled layer provides stable support for enzyme immobilization. When the sensor operates at a set potential (e.g., -0.2V), the SOD immobilized on the electrode surface catalyzes the formation of superoxide anions (O2-). -·) occurs, oxygen and hydrogen peroxide are generated, and the copper ion in SOD cycles between Cu(II) / Cu(I) and participates in electron transfer, which forms a current response on the electrode surface, and the current intensity is positively correlated with the concentration of O2 -· , realizing its efficient and sensitive detection.

[0095] (1) Construction of gold nanoparticles (AuNPs) layer: AuNPs were loaded on the spindle-shaped carbon nanotube fiber by constant potential point deposition (-0.2 V, 30 s) to construct a functionalized substrate with high surface area.

[0096] (2) Construction of cysteine self-assembled monolayer: The construction of the cysteine self-assembled monolayer was carried out by immersion method. The spindle-shaped carbon nanotube fiber loaded with AuNPs was immersed in a 1 mM cysteine solution and incubated at room temperature for 1 hour to form a stable cysteine self-assembled monolayer (SAM) on the Au surface. This layer provides abundant thiol and amino functional groups, which is conducive to the subsequent enzyme immobilization.

[0097] (3) Immobilization of superoxide dismutase (SOD) layer: The functionalized fiber was immersed in an SOD (6000 U / mL) solution, and adsorption was allowed to stand for 18 hours to complete the construction of the superoxide anion sensor.

[0098] The O2 ·- solutions (760 nM / decade) were tested, and the fiber sensor showed good sensitivity and linearity (sensitivity: 470 nA / μM, R 2 = 0.994), as shown in Figure 10 .

[0099] Example 5

[0100] To verify the performance stability of the sensor during the reversible deformation process, the spindle-shaped carbon nanotube fiber H2O2 sensor constructed in Example 3 and the O2 ·- sensor were tested by electrochemical test in the expanded state. Then, the fiber was restored to the initial unexpanded state by manual tightening (the diameter of the local expansion area after tightening was less than 10% of the diameter of the local expansion area before tightening). Subsequently, the detection sensitivity of the sensor before and after tightening was compared under the same detection conditions. As shown in Figure 11 , the response change rate of the sensor fiber before and after tightening was less than 25%, indicating that the sensor could maintain high sensitivity stability after experiencing reversible deformation, and the performance change was within an acceptable range, showing good mechanical-electrochemical coupling stability.

[0101] Example 6

[0102] The embodiment provides a multi-parameter electrochemical detection device 9, which comprises an implanting part 1, an integrated part and a connecting back-end detection equipment part 2, and specifically as follows:

[0103] Three functional fibers (i.e. glucose sensing fiber 6, hydrogen peroxide sensing fiber 7 and superoxide anion sensing fiber 8) prepared by example 2 (Glu), example 3 (H2O2) and example 4 (O2 ·- ) are integrated into a five-core sensing probe in the middle through a medical heat shrink tube 3 together with an Ag / AgCl reference electrode 4 and a carbon fiber counter electrode 5 to form the integrated part, the fibers are parallel to each other, and the rest of the part except the front end working area (i.e. the implanting part 1) is packaged by using an insulating coating, as shown in Figure 12 .

[0104] The multi-parameter electrochemical detection device 9 can be easily implanted into tissues through the assisted puncture mode of a medical buried wire needle 10, and the overall device schematic diagram is as shown in Figure 13 . In addition, a portable electrochemical workstation or an integrated circuit board can be used to record multi-channel signals. The current signals of the three target substances can be independently identified, the response speed is fast, the signal has no crosstalk, and the device is suitable for minimally invasive implantable real-time dynamic monitoring.

[0105] Comparative example

[0106] In order to verify the advantages of the "spindle-shaped carbon nanotube fiber embedded sensing layer structure" in stability and sensitivity in the application, the comparative example adopts a traditional unexpanded carbon nanotube fiber as a sensing substrate, and constructs three types of sensors (Glu, H2O2 and O2 ·- ) through the same surface modification method, and compares with the sensors of the application described in examples 2, 3 and 4.

[0107] (1) Sensing layer modification position comparison

[0108] As shown in Figure 5 a and b, the sensors constructed by the intrinsic carbon nanotube fiber are of the traditional surface modification type, and the sensing material is mainly distributed on the surface of the fiber, and the sensing layer cannot be modified in the carbon nanotube network inside the fiber (c).

[0109] (2) Sensor performance comparison

[0110] The performances of the three sensors obtained in the above comparative example are tested respectively, and compared with the performances of the embedded modification structure of examples 2-4.

[0111] As shown in Figure 8 , Figure 10As shown, the intercalated modification sensor based on the spindle-shaped carbon nanotube fiber of the present application has higher sensitivity than the original carbon nanotube fiber sensor in the same conditions and the same concentration range for detecting H2O2, O2 ·- , respectively, with 10 times and 5 times increase in sensitivity.

[0112] Meanwhile, in order to verify the high-efficiency protection of the intercalated modification structure and the reversible deformation on the sensitive layer, the Glu sensor was woven into a fabric and tested by a spin tester (5 min / time) to simulate washing. As shown, Figure 14 compared with the intrinsic carbon nanotube fiber sensor, the reversible deformation spindle-shaped carbon nanotube fiber sensor prepared by the present application has more excellent stability (after 50 times of continuous washing, the sensitivity retention rate of the intrinsic carbon nanotube fiber sensor is less than 40%; while the sensitivity retention rate of the spindle-shaped carbon nanotube fiber sensor is about 100%, almost unchanged), which verifies the high-efficiency protection of the intercalated modification structure and the reversible deformation on the sensitive layer.

[0113] The details of the present application are known technologies.

[0114] The above-described embodiments are only a preferred scheme of the present application, and are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical scheme obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A method for preparing a high-stable reversible deformation carbon nanotube fiber sensor, characterized in that, Specifically as follows: The local expansion area in the middle of the intrinsic carbon nanotube fiber is expanded, so that the local expansion area has reversible deformation ability and presents a spindle shape, and the carbon nanotube network originally buried in the intrinsic carbon nanotube fiber is fully exposed; a sensitive material is modified in the exposed carbon nanotube network to form a sensitive layer, and the sensitive material can realize high-sensitivity electrochemical detection of a target marker; then the intrinsic carbon nanotube fiber is screwed, so that the local expansion area returns to a slender structure, the sensitive layer is closed and protected, and subsequent minimally invasive implantation is facilitated.

2. The production method according to claim 1, characterized by, The maximum diameter of the expanded local expansion area is 30 times or more than the diameter of the rest of the intrinsic carbon nanotube fiber, and the diameter of the local expansion area after screwing is less than 10% of the diameter during expansion.

3. The production method according to claim 1, characterized by, The expansion treatment method includes electrochemical expansion, bubble-induced reconstruction, mechanical stretching, electric field induction, and heat treatment.

4. The preparation method according to claim 1, characterized in that, A protective layer is coated outside the local expansion area after screwing; the protective layer material includes polyurethane, polyvinyl chloride, chitosan, and zwitterionic polymer.

5. The preparation method according to claim 1, characterized in that, The sensitive layer is obtained by one of the following three ways: S1: The sensitive material is a biological recognition element and an electrocatalytic material; the electrocatalytic material is modified in the carbon nanotube network first, and then the biological recognition element is modified, so as to catalyze the decomposition and conversion of the product reacted by the biological recognition element into an electrical signal that can be directly measured; The biological recognition element is glucose oxidase or lactate oxidase; S2: The sensitive material is superoxide dismutase, a cysteine layer, and an electrocatalytic material; the electrocatalytic material, cysteine, and superoxide dismutase are sequentially modified in the carbon nanotube network, the electrocatalytic material is used to fix the cysteine, and then the cysteine is connected and fixed with the superoxide dismutase, and a direct electron transfer effect of the superoxide dismutase is used to form an electrical signal that can be directly measured; S3: The sensitive material is an electrocatalytic material with enzyme-like properties and capable of catalyzing the decomposition of hydrogen peroxide, which specifically catalyzes H2O2 and realizes electron transfer to form an electrical signal that can be directly measured.

6. The production method according to claim 5, wherein The electrocatalytic material is a metal nanoparticle or an inorganic compound, including gold, platinum, and Prussian blue; the electrocatalytic material is modified in the carbon nanotube network by electrodeposition, physical adsorption, or covalent bonding.

7. The preparation method according to claim 5, characterized in that, In S2, the cysteine is self-assembled into a cysteine monolayer by direct immersion.

8. The preparation method according to claim 5, characterized in that, The biological recognition element and the superoxide dismutase are both modified in the carbon nanotube network by physical adsorption, covalent bonding, electropolymerization, or chemical crosslinking.

9. A high-stability reversible deformation carbon nanotube fiber sensor obtained by the preparation method of any one of claims 1-8.

10. A multi-parameter electrochemical detection device, characterized in that, It includes at least three high-stability reversible deformation carbon nanotube fiber sensors as claimed in claim 9, one reference electrode fiber, and one counter electrode fiber, and all fibers are packaged into an integrated flexible implantable integrated sensing assembly.

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