Conductive nano material glucose sensing material and preparation method and application thereof
Technical Field
The invention relates to the technical field of special materials for intelligent monitoring of glucose and application, in particular to a conductive nanomaterial glucose sensing material and a preparation method and application thereof.
Background
Currently commercialized continuous blood glucose detectors (CGMS) all use an electrochemical method based on an enzyme reaction to convert glucose concentration into an electric signal in real time. The CGMS products all contain glucose oxidase, and the glucose oxidase can specifically recognize glucose and is insensitive to other saccharides in organisms. The technologies currently used for commercial CGMS can be classified into a first generation enzyme technology and a second generation wired enzyme technology.
The first generation of enzyme technology is to indirectly detect glucose concentration by detecting the concentration of hydrogen peroxide generated during glucose oxidation, and the working electrode used is usually a noble metal electrode. The generation of hydrogen peroxide requires the consumption of oxygen, and the concentration of oxygen in human blood (0.2-0.3 mM) is far lower than the concentration of glucose in blood (5-10 mM), so that a specially designed biocompatible outer film capable of simultaneously controlling the oxygen and glucose flux needs to be covered on the surface of a glucose sensor. Such outer film materials are complex in structure and similar techniques are disclosed in, for example, patent application publication nos. CN201080053713.4, CN201080062485.7, CN201980030243.0, etc. In addition, the diffusion direction of the generated hydrogen peroxide in the sensing layer is not limited, and only the hydrogen peroxide diffused to the surface of the electrode can generate current for sensing, so that high requirements are placed on the preparation process of the electrode. In addition, the detection potential used in the first generation enzyme technology is usually 0.4V or more. At this potential, some interfering substances, such as ascorbic acid, acetaminophen, are oxidized, creating an interfering current. Therefore, the effective working time of CGMS based on the first generation enzyme technology is generally varied from 7 days to 10 days.
The second generation of wired enzyme technology is to replace oxygen by artificially synthesizing a mediator to realize electron transfer between glucose oxidase and an electrode. The electron mediator is grafted to the side chains of the polymer through a long flexible chain, and specific technical details are as described in U.S. patent application publication No. US 6605200B 1. The redox center Flavin Adenine Dinucleotide (FAD) of glucose oxidase is wrapped by a thicker insulating layer, and the medium with long flexible chain can realize effective contact with the FAD to transfer electrons. And forms carriers such as electrons or holes through rapid reduction and rapid oxidation, and conducts current through self-exchange. The reduced mediator collides with the oxidized mediator, the reduced mediator transfers electrons, or the oxidized mediator transfers holes. Although in theory, electrons or holes can also propagate by hopping between the fixed-position mediators, there is little solid-state physical trap-jump seen in redox hydrogels. The long flexible chain's mediator transfers electrons faster than the short chain's mediator because the long flexible chain increases the displacement amplitude of the tethered mediator, significantly increasing the contact collision frequency. In addition, in the patent application document with the patent application number of CN200980139400.8, the electron mediator with different redox potentials is synthesized by adjusting the ligand of the synthesized mediator, and the redox potential of the electron mediator is generally less than 0.3V, so that the anti-interference capability of CGMS is improved. Although the artificially synthesized mediator replaces oxygen to realize electron transfer between glucose oxidase and the electrode, the oxygen still can be in electron transfer with the glucose oxidase. There is a competing relationship between oxygen and synthetic mediums. Therefore, in CN 113521399A, US 6932894B 2 and the like, a biocompatible outer membrane was prepared to reduce the permeation of oxygen into the sensing layer, while also controlling the flux of glucose into the sensing layer. Through this outer membrane, the interference of oxygen is reduced. However, oxygen, which is a small molecule dissolved in body fluid, still diffuses into the sensing layer in the slightly swelled pores along with water molecules, competing with an electron mediator to transfer electrons of glucose oxidase. If the crosslinking degree of the membrane is increased, the inflow of oxygen is reduced, and the detection range of CGMS is further increased, but the sensitivity is lowered, and the detected current value is also increased by external interference.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a special material for intelligent monitoring of glucose and application thereof, so as to solve the problems of reduced sensitivity, weakened anti-interference capability and the like caused by the interference of oxygen in the process of detecting the glucose by the existing second-generation CGMS wired enzyme technology.
The technical scheme adopted by the invention is as follows:
a special material for conducting nano material glucose is prepared from conducting nano material containing redox ligand and glucose oxidase through covalent cross-linking by cross-linking agent.
The preparation method of the special material for the conductive nano material glucose comprises the following steps:
(1) Firstly, carrying out surface modification treatment on the surface of the conductive nano material by using a silane coupling agent to enable the surface to have active groups;
(2) The modified conductive nano material is connected with an oxidation-reduction ligand through a covalent bond;
(3) The conductive nano material connected with the redox ligand and glucose oxidase are subjected to covalent cross-linking through a cross-linking agent.
Preferably, the conductive nanomaterial in step (1) is one or more of graphite alkyne, nanogold, nanosilver, nanoplatinum, nano conductive carbon black, carbon nanotube, soccer graphene, graphene or reduced graphene oxide.
Preferably, the silane coupling agent described in step (1) has the general formula Y (CH) 2 ) n SiX 3 Wherein n=0 to 3, and X is one or more of methoxy, ethoxy, methoxyethoxy and acetoxy; and Y is one of vinyl, amino, epoxy, methacryloxy, mercapto or ureido.
Preferably, the redox ligand described in step (2) has the general formula Os (L) 2 RCl n Or Ru (L) 2 RCl n Wherein L is a ligand containing two nitrogen heterocycles, R is a mono-or di-heterocyclic ligand containing a reactive group, n=1 if R is a mono-heterocyclic ligand containing a reactive group, and n=0 if R is a di-heterocyclic ligand containing a reactive group.
Further, the L is one of N, N ' -dimethyl-2, 2' -biimidazole, 2' -bipyridine, 4' -dimethyl-2, 2' -bipyridine, 4' -dimethoxy-2, 2' -bipyridine, 4' -dichloro-2, 2' -bipyridine and 4,4' -diamino-2, 2' -bipyridine;
further, R is one of imidazole, pyridine, bipyridine, biimidazole and dipyridyl biimidazole with amino, carboxyl or aldehyde groups.
Preferably, the cross-linking agent in the step (3) is one or more of glutaraldehyde, polyethylene glycol diglycidyl ether, poly (propylene glycol) diglycidyl ether, 1, 4-butanediol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane (ethane) triglycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, genipin.
Preferably, the crosslinking reaction of step (3) is: mixing the conductive nano material connected with the redox ligand, glucose oxidase and a cross-linking agent solution according to a cross-linking reaction feeding ratio, and reacting for 45 min-2 d at the temperature of 20-45 ℃.
The invention also provides application of the conductive nanomaterial glucose special material in blood glucose monitoring and diabetes management instruments.
In summary, compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention increases the rate of electron transfer of the electron mediator by the conductive nano material with the oxidative reduction ligand, thereby overcoming the oxygen effect in the second generation wired enzyme technology; the electrochemical glucose sensor prepared by the sensing material provided by the invention can specifically detect glucose, has high linear correlation coefficient between a stable current signal and glucose concentration, and can eliminate the influence of an interfering substance acetaminophen on glucose detection, so that the conductive nano glucose sensing material based on oxidative reduction ligand modification has wide application value in intelligent glucose detection;
2. in the invention, the redox ligand serving as the electron mediator directly transfers electrons to the next electron mediator through collision or to a plurality of electron mediators connected to the surface of the conductive nanomaterial or directly transferred to the electrode through the high-conductivity nanomaterial to realize multi-path transfer, and the method greatly increases the electron transfer rate of the electron mediator and effectively overcomes the oxygen effect;
3. the conductive nano material glucose sensing material provided by the invention has long effective working time due to multi-channel electron transfer and structural stability, and the working performance of the conductive nano material glucose sensing material cannot be influenced with time change.
Drawings
The invention will now be described by way of example and with reference to the accompanying drawings, which show the results of tests performed on the examples:
FIG. 1 is a cyclic voltammogram of a glucose sensing layer reagent coated with a biocompatible layer in PBS according to examples 1-5 of the present invention.
FIG. 2 is a graph showing the time-current profile of a glucose sensing layer reagent coated with a biocompatible layer in 0-40mM glucose PBS in examples 1-5 of the present invention.
FIG. 3 is an anti-interference test of examples 1-5 of the present invention after a reagent coating of a biocompatible layer.
FIG. 4 is a test experiment under different oxygen concentrations after the reagent of the glucose sensing layer is coated with a biocompatible layer according to examples 1 to 5 of the present invention.
FIG. 5 is a long-term stability test of the glucose sensing layer reagent of examples 1-5 of the present invention after coating with a biocompatible layer.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention, i.e., the embodiments described are merely some, but not all, of the embodiments of the invention.
Example 1
The embodiment provides a conductive nanomaterial glucose sensing material modified based on redox ligands, and the preparation process comprises the following steps:
A. weighing 1-100 mg of multi-wall carbon nano tube, placing the multi-wall carbon nano tube into a 10mL small bottle, adding 1-3 mL of deionized water and 0.01-1 mL of 3-aminopropyl triethoxysilane, carrying out ultrasonic treatment for 10-100 min to obtain uniform dispersion liquid, placing the uniform dispersion liquid at 25-50 ℃ for 1-24 h, adding 0.1-100 mu L of 0.1M hydrochloric acid into the uniform dispersion liquid, placing the uniform dispersion liquid at room temperature for 6-48 h, dialyzing the obtained suspension liquid, and carrying out centrifugal cleaning on the dialyzed suspension liquid for multiple times to obtain the carbon nano tube with amino groups on the surface.
B. 10-100 mg Os (bpy) 2 ClIm(CH 2 ) 11 -COOH was dissolved well in PBS at ph=5-8 with stirring, then 150mg 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride and 200mg N-hydroxysuccinimide were added and stirred at room temperature for 15-60 min. 100. Mu.L of 200mg/mL of the dispersion of aminated carbon nanotubes (pH=7.4) was added dropwise, and the mixture was stirred at room temperature for 12 to 72 hours. After the reaction is finished, the product obtained by centrifugal cleaning with deionized water is dialyzed with deionized water to remove small molecules in a free state, and the carbon nano tube of the surface modified redox ligand is obtained.
C. And (2) mixing 10 mu L of the carbon nanotube dispersion liquid (10 mg/mL) of the surface modified redox ligand obtained in the step B and 10 mu L of glucose oxidase solution (10 mg/mL) through 10 mu L of 5% glutaraldehyde solution for 45min, and dripping the mixture onto the surface of an electrode to obtain the redox ligand modified conductive nanomaterial glucose sensing layer reagent.
Example 2
The embodiment provides a conductive nanomaterial glucose sensing material modified based on redox ligands, and the preparation process comprises the following steps:
A. weighing 1-100 mg of graphene, placing the graphene into a 10mL small bottle, adding 1-3 mL of deionized water and 0.01-1 mL of methacryloxypropyl trimethoxysilane, carrying out ultrasonic treatment for 10-100 min to obtain uniform dispersion, placing the uniform dispersion at 25-50 ℃ for 1-24 h, adding 0.1-100 mu L of 0.1M hydrochloric acid into the uniform dispersion, placing the uniform dispersion at room temperature for 6-48 h, dialyzing the obtained suspension, and centrifugally cleaning the dialyzed suspension for multiple times to obtain graphene with acryloxy groups on the surface.
B. 10-100 mg Os (diamino-bpy) 2 ClIm(CH 2 ) 11 -NH 2 Fully dissolved in ethanol under stirring, 100 mu L of acryloyloxy modified graphene dispersion liquid with the concentration of 200mg/mL is added, and the mixture is stirred for 1 to 12 hours at the temperature of between 40 and 90 ℃. After the reaction is completed, the obtained product is centrifugally washed by ethanol, dialyzed by deionized water and removedAnd (3) obtaining the graphene with the surface modified redox ligand by the small molecules in a free state.
C. And (3) mixing 10 mu L of the graphene dispersion liquid (10 mg/mL) of the surface modified redox ligand obtained in the step (B) and 10 mu L of glucose oxidase solution (10 mg/mL) through 10 mu L of polyethylene glycol diglycidyl ether solution (10 mg/mL), then dripping the mixture onto the surface of an electrode, and drying the mixture in vacuum at room temperature for 48 hours to obtain the glucose sensing layer reagent based on the redox ligand modified conductive nano material.
Example 3
The embodiment provides a conductive nanomaterial glucose sensing material modified based on redox ligands, and the preparation process comprises the following steps:
A. weighing 1-100 mg of nano conductive carbon black, placing the nano conductive carbon black into a 10mL small bottle, adding 1-3 mL of deionized water and 0.01-1 mL of gamma-glycidoxypropyl trimethoxysilane, carrying out ultrasonic treatment for 10-100 min to obtain uniform dispersion, placing the uniform dispersion for 1-24 h at 25-50 ℃, adding 0.1-100 mu L0.1M hydrochloric acid into the uniform dispersion, placing the uniform dispersion for 6-48 h at room temperature, dialyzing the obtained suspension, and carrying out centrifugal cleaning on the dialyzed suspension for multiple times to obtain the nano conductive carbon black with epoxy groups on the surface.
B. 10-100 mg Os (dimethyl-bpy) 2 ClIm(CH 2 ) 11 -NH 2 Fully dissolved in ethanol under stirring, 100 mu L of epoxy modified conductive carbon black dispersion liquid with the concentration of 200mg/mL is added, and the mixture is stirred for 1 to 12 hours at the temperature of 40 to 90 ℃. After the reaction is finished, the product obtained by centrifugal washing with ethanol is dialyzed by deionized water to remove small molecules in a free state, and the nano conductive carbon black of the surface modified redox ligand is obtained.
C. And (2) mixing 10 mu L of the nano conductive carbon black dispersion liquid (10 mg/mL) of the surface modified redox ligand obtained in the step (B) and 10 mu L of glucose oxidase solution (10 mg/mL) through 10 mu L of 1, 4-butanediol diglycidyl ether solution (10 mg/mL), then dripping the mixture onto the surface of an electrode, and drying the mixture at room temperature in vacuum for 48 hours to obtain the glucose sensing layer reagent based on the redox ligand modified conductive nano material.
Example 4
The embodiment provides a conductive nanomaterial glucose sensing material modified based on redox ligands, and the preparation process comprises the following steps:
A. 1-100 mg of nano conductive graphite alkyne is weighed and placed in a 10mL small bottle, 1-3 mL of deionized water and 0.01-1 mL of 3- (2-amino ethyl amino) propyl trimethoxy silane are added, the ultrasonic treatment is carried out for 10-100 min, uniform dispersion liquid is obtained, the uniform dispersion liquid is placed for 1-24 h at 25-50 ℃, 0.1-100 mu L of 0.1M hydrochloric acid is added, the uniform dispersion liquid is placed for 6-48 h at room temperature, the obtained suspension liquid is dialyzed, and the suspension liquid with amino groups on the surface is obtained after the dialysis is washed by centrifugation for many times.
B. 10-100 mg Os (dimethoxy-bpy) 2 ClIm(CH 2 ) 11 Sufficiently dissolving in PBS with pH=5-8 under stirring of-COOH, then adding 150mg of 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride and 200mg of N-hydroxysuccinimide, and stirring at room temperature for 15-60 min. 100 μl of 200mg/mL aminated nano conductive graphite alkyne dispersion (ph=7.4) was added dropwise, and stirred at room temperature for 12-72 h. After the reaction is finished, the product obtained by centrifugal cleaning with deionized water is dialyzed with deionized water to remove small molecules in a free state, and the nano conductive graphite alkyne of the surface modified redox ligand is obtained.
C. And (2) mixing 10 mu L of the nano conductive graphite alkyne dispersion solution (10 mg/mL) of the surface modified oxidative reductive ligand obtained in the step (B) and 10 mu L of glucose oxidase solution (10 mg/mL) through 10 mu L of 1, 6-hexanediol diglycidyl ether solution (10 mg/mL), then dripping the mixture onto the surface of an electrode, and drying the mixture in vacuum at room temperature for 48 hours to obtain the glucose sensing layer reagent based on the conductive nanomaterial modified by the oxidative reductive ligand.
Example 5
The embodiment provides a conductive nanomaterial glucose sensing material modified based on redox ligands, and the preparation process comprises the following steps:
A. weighing 100 mu L of nano gold dispersion liquid, placing the nano gold dispersion liquid into a 10mL small bottle, adding 1-3 mL of deionized water and 0.01-1 mL of 3- (2-amino ethyl amino) propyl trimethoxy silane, carrying out ultrasonic treatment for 10-100 min to obtain uniform dispersion liquid, placing the uniform dispersion liquid at 25-50 ℃ for 1-24 h, adding 0.1-100 mu L of 0.1M hydrochloric acid into the uniform dispersion liquid, placing the uniform dispersion liquid at room temperature for 6-48 h, dialyzing the obtained suspension liquid, and carrying out centrifugal cleaning on the dialyzed suspension liquid for multiple times to obtain the nano gold with amino on the surface.
B. 10-100 mg of Os (N, N '-dialkylated-2,2' -bi-imidazole) 2 Im-ImCOOH was sufficiently dissolved in PBS having pH=5 to 8 under stirring, 150mg of 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride and 200mg of N-hydroxysuccinimide were then added, and the mixture was stirred at room temperature for 15 to 60 minutes. 100 mu L of amination nano conductive nano gold dispersion liquid (pH=7.4) with the concentration of 200mg/mL is added dropwise, and the mixture is stirred for 12 to 72 hours at room temperature. After the reaction is finished, the product obtained by centrifugal cleaning with deionized water is dialyzed with deionized water to remove small molecules in a free state, and the nano conductive gold of the surface modified redox ligand is obtained.
C. And (2) mixing 10 mu L of the nano conductive gold dispersion liquid (10 mg/mL) of the surface modified redox ligand obtained in the step (B) and 10 mu L of glucose oxidase solution (10 mg/mL) through 10 mu L of 1,6 polypropylene glycol diglycidyl ether solution (10 mg/mL), then dripping the mixture onto the surface of an electrode, and drying the mixture in vacuum at room temperature for 48 hours to obtain the glucose sensing layer reagent based on the redox ligand modified conductive nano material.
The cyclic voltammograms of these working electrodes in phosphate buffer solution at ph=7.4 were tested with the electrodes obtained as described in examples 1-5 as working electrodes, silver/silver chloride as reference electrode, and platinum wire as reference electrode, respectively. As can be seen from FIG. 1, the redox peaks of these electrodes are below 0.3V, which is far below the voltage required for catalytic oxidation of acetamido by interfering substances. Therefore, the electrodes have better anti-interference capability.
A time current profile was performed in 0-40mM glucose PBS after coating a biocompatible layer with the glucose sensing layer reagents of examples 1-5, respectively, with an increasing glucose concentration of 5mM each time. As shown in fig. 2, as the glucose concentration increases, the current signal value also increases. And the glucose concentration and the current signal value have a relatively good linear relationship. The results show that these electrodes prepared are capable of better testing glucose concentrations in the glucose concentration range of 0-40 mM.
The anti-interference experiments were performed after wrapping a biocompatible layer with the glucose sensing layer reagents of examples 1-5, respectively. As shown in FIG. 3, the current signal values of these electrodes were linearly related to the glucose concentration, and then the PBS solution was replaced again, and 5mM of acetaminophen was added, and the current values were hardly changed. The results indicate that the prepared electrodes are not substantially responsive to acetaminophen, which indicates that the electrodes have a strong anti-interference capability to acetaminophen.
Test experiments were performed at different oxygen concentrations after wrapping a biocompatible layer with the glucose sensing layer reagent of examples 1-5, respectively. As shown in FIG. 4, the current signal values of these electrodes are relatively linearly related in the range of 0-40mM glucose concentration in a 5% oxygen atmosphere. The subsequent bubbling of nitrogen changes the oxygen concentration of the test environment with little change in current value. The results indicate that the electrodes produced are less disturbed by the oxygen concentration.
The long-term stability test was performed after wrapping a biocompatible layer with the glucose sensing layer reagent of examples 1-5, respectively. The electrodes were tested daily for sensitivity after 15 days of continuous operation in the test solution, and the results are shown in fig. 5. Where the sensitivity on day 0 is the unsterilized electrode test result and the reason for the lower sensitivity on day 1 than on the following 14 days is that the biocompatible layer is not fully swelled in equilibrium. These electrodes showed little change in sensitivity over the next 14 days, which indicated good long-term stability of the prepared electrodes.
The foregoing examples merely represent specific embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that, for those skilled in the art, several variations and modifications can be made without departing from the technical solution of the present application, which fall within the protection scope of the present application.