CN113219030A - CuPi/Ti3C2Preparation of quantum dot composite material and application of photo-electrochemical sensor in kanamycin detection based on quantum dot composite material - Google Patents

Abstract

The invention discloses a CuPi/Ti₃C₂Preparation of quantum dot composite material and application of the photoelectrochemical sensor in kanamycin detection. The CuPi/Ti₃C₂The preparation of the QDs composite material comprises the following steps: (1) mixing CuPi and 10-15mg/mLTi₃C₂Mixing the QDs water solution according to the mass-volume ratio of 2:1-4:1, and carrying out ultrasonic treatment for 5-10min under the ultrasonic power of 150-300W to obtain a mixed solution; (2) stirring the mixed solution at the rotation speed of 300-500rpm at room temperature for 20-30min, then centrifuging at 3500-5000rpm, and freeze-drying the precipitate to obtain CuPi/Ti₃C₂QDs composites. The photoelectrochemical sensor is formed by sequentially loading the CuPi/Ti on a glassy carbon electrode from bottom to top₃C₂QDs composite material, gold nanoparticles, kanamycin aptamer DNA and BSA. CuPi prepared by the invention/Ti₃C₂The QDs composite material has good energy level matching, and the rapid electron transfer provides higher sensitivity for the detection of kanamycin. The photoelectrochemical sensor is applied to kanamycin detection, has good sensitivity, and has good linear response in the range of 1-10000 pM.

Description

CuPi/Ti3C2Preparation of quantum dot composite material and application of photo-electrochemical sensor in kanamycin detection based on quantum dot composite material

Technical Field

The invention belongs to the technical field of photoelectric chemical sensing preparation and application, and particularly relates to CuPi/Ti₃C₂Preparation of QDs composite material, photoelectrochemical sensor based on the composite material, preparation of the photoelectrochemical sensor and application of the photoelectrochemical sensor in kanamycin detection.

Background

The sensing technology is one of three major pillars in the information industry, and monitors specific events according to a certain rule through specific sensors and converts the events into readable signals so as to meet the requirements of information acquisition and analysis. The application of the sensing technology relates to the aspects of social life, and various functions of the sensor cannot be separated from the activities of modern human beings. As an active branch of the sensing discipline, rapid, sensitive detection of chemical and biological species plays an essential role in a wide range of research and applications. Various sensing technologies based on electrochemistry, electronics, optics (fluorescence, absorption, chemiluminescence, surface plasmon resonance and raman spectroscopy) and mechanics (micro-cantilevers) have been developed. However, how to meet the increasing sensing requirements with low cost, high sensitivity, convenient operation, etc. is still a great challenge.

Electronic probe bioanalysis has received much attention because of its higher sensitivity, lower background effects than traditional electrochemical methods, and the advantages of being simpler, cheaper, and more amenable to miniaturization than optical methods. Decades of development have established the key role of quantum dots in optical, biomedical and environmental applications, and various quantum dots, including single, double and multi-element quantum dots, have been studied and discussed previously. The explosion of quantum dots is highly dependent on emerging new quantum dot sources and new methods of modifying existing quantum dots. The prior literature indicates that the two-dimensional nanosheet is important for novel quantum dotsThe source of the quantum dots is that the quantum dots can integrate the advantages of raw materials and the advanced performance generated by the size effect. The two-dimensional nanoplatelets library includes various members such as black phosphorus, silylene, MXenes, and transition metal dichlorides. In particular, multi-element quantum dots made of two-dimensional transition metal carbides (MXenes) have attracted increasing research interest. By cutting two-dimensional Ti₃C₂Tx, MXenes derived quantum dots are commonly named Ti₃C₂QDs, which inherits the hydrophilicity, conductivity and biocompatibility of MXenes, while having unique optical and optoelectronic properties. With its application in the fields of cell imaging and biosensing, Ti₃C₂The application of quantum dots is rapidly growing, but to Ti₃C₂The development of modification strategies for quantum dots has not paved the way for this growth. The development processes of other quantum dots including quantum dots etched by two-dimensional graphene and quantum dots synthesized by a bottom-up method are observed, and doping is an important way for improving the performance of the quantum dots. The electronic properties and the structure of the quantum dots can be obviously changed by doping elements such as nitrogen, copper, phosphorus and the like, so that the quantum dots have higher quantum yield, better stability, water solubility and more surface active centers. Therefore, search for Ti₃C₂Doping strategy of quantum dots and modified Ti₃C₂Subsequent applications of quantum dots have urgent research needs.

Kanamycin (kanamyin, Kana) is an aminoglycoside antibiotic, and is often used as a feed additive or a therapeutic agent in agriculture, animal husbandry and aquaculture due to low price and good antibacterial activity, and certain drug residues can be caused in rivers, underground water and even drinking water due to unreasonable discharge of synthetic waste liquid and other factors. However, kanamycin can be left in animal-derived foods due to abuse, side effects such as toxicity, nephrotoxicity and antibiotic resistance can be caused when the foods containing kanamycin residues are taken for a long time, and toxic effects such as renal injury, anaphylactic reaction and drug resistance can be caused to a human body when water exceeding the standard is frequently drunk. In recent years, the over-standard antibiotics in drinking water happens frequently, and the safety of people is seriously threatened, so that the development of a novel detection technology is urgent and necessary.

At present, enzyme-linked immunosorbent assay, high performance liquid chromatography, capillary electrophoresis and the like are used as kanamycin detection technologies, and although the methods are high in accuracy, expensive large-scale equipment and professional operators are needed, and complicated pretreatment processes are needed, so that the time is long. Therefore, it is necessary to establish a rapid, sensitive, low-cost method for detecting kanamycin residues in food.

Disclosure of Invention

The first purpose of the invention is to provide a method for preparing CuPi/Ti₃C₂Methods of QDs composites.

It is a second object of the present invention to provide a photoelectrochemical sensor for kanamycin detection.

The third purpose of the invention is to provide a preparation method of a photoelectrochemical sensor for kanamycin detection.

The fourth purpose of the invention is to provide the application of the photoelectrochemical sensor in kanamycin detection.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a CuPi/Ti₃C₂The preparation method of the QDs composite material comprises the following steps:

step (1): mixing CuPi and 10-15mg/mLTi₃C₂Mixing the QDs water solution according to the mass-volume ratio of 2:1-4:1, and carrying out ultrasonic treatment for 5-10min under the ultrasonic power of 150-300W to obtain a mixed solution;

step (2): stirring the mixed solution in the step (1) at the rotating speed of 300-500rpm at room temperature for 20-30min, then centrifuging at 3500-5000rpm, and freeze-drying the precipitate to obtain CuPi/Ti₃C₂QDs composites.

The CuPi/Ti of the invention₃C₂A method for preparing QDs composite material, various combinations of preparation conditions within the defined ranges, such that CuPi/Ti₃C₂The QDs composite material has better performance. In particular, the invention is based on the construction of heterojunctionsSynthesis of CuPi/Ti₃C₂QDs composites. Since CuPi is a p-type semiconductor, Ti₃C₂QDs are n-type semiconductors with good energy level matching (valence band VB of CuPi of 3.59eV, conduction band CB of 0.19 eV; Ti₃C₂The valence band VB of QDs is 2.49eV, the conduction band CB is-0.42 eV), and photogenerated holes generated on the valence band VB of CuPi can be transferred to Ti under the illumination condition₃C₂Valence bands VB, Ti of QDs₃C₂Photo-generated electrons generated on the conduction band CB of QDs can be transferred to Ti₃C₂The conduction band CB of QDs promotes the separation of photo-generated electrons and holes, resulting in an increase in photocurrent intensity.

In the present invention, the CuPi and Ti are₃C₂QDs can be synthesized according to literature reports. For example, the synthesis of CuPi can be found in the references [ C.Ye, M.Q.Wang, L.J.Li, H.Q.Luo, N.B.Li, contamination of Pt/Cu₃(PO₄)₂Ultrathin Nanosheet Heterostructure for Photoelectrochemical MicroRNA Sensing UsingNovel G-Wire-Enhanced Strategy,Nanoscale 9(2017)7526–7532.]；Ti₃C₂The synthesis of QDs can be carried out in two steps: first preparing to obtain Ti₃C₂Nanosheet, recycled Ti₃C₂Preparing a nanosheet to obtain Ti₃C₂QDs. Wherein Ti₃C₂The Synthesis of nanosheets can be found in the literature [ M.Alhabeb, K.Maleski, B.Anasori, P.Lelyukh, L.Clark, S.sin, Y.Gogotsi, Guidelines for Synthesis and Processing of two-Dimensional Titanium Carbide (Ti)₃C₂Tx MXene),Chem.Mater.29(2017)7633-7644.]，Ti₃C₂The synthesis of QDs is described in the literature [ X.Chen, W.Xu, N.Ding, Y.Ji, C.Pan, J.Zhu, D.ZHou, Y, Wu, C.Chen, H.Song, Dual Interactive Modification Engineering with 2D MXene Quantum Dots and compressor sulfate Nanocrystals Enabled High-performance Perforskolite Solarcells, adv.Funct.Mater.2020, 2003295. Ding]。

In a second aspect, the invention provides a photoelectrochemical sensor for kanamycin detection, which sequentially loads CuPi/Ti on a glassy carbon electrode from bottom to top₃C₂QDs compoundsThe preparation method comprises the following steps of (1) combining materials, gold nanoparticles, kanamycin aptamer DNA and BSA; the DNA sequence of the kanamycin aptamer is as follows: 5' -HS- (CH)₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3′。

In the invention, CuPi/Ti is firstly formed on the surface of a glassy carbon electrode₃C₂QDs composite material film, and CuPi/Ti₃C₂Au nano particles are modified on the surface of QDs, kanamycin aptamer DNA is modified, an aptamer DNA chain is fixed on the surface of an electrode through the interaction of Au-S bonds, BSA (bovine serum albumin) is combined with non-specific binding sites of the aptamer DNA chain to block the non-specific binding sites of the aptamer DNA chain, finally the sensor can be specifically combined with kanamycin, and under the condition that kanamycin exists, the sensor can be used as an electron donor to consume photo-generated holes generated by a composite material, so that the photocurrent intensity is increased, and the kanamycin can be quantitatively detected.

In the present invention, the gold nanoparticles can be prepared according to the methods reported in the literature, for example, gold nanoparticles can be synthesized by using trisodium citrate reduction method, specifically, the references are cited [ x.liu, p.liu, y.tang, l.yang, l.li, z.qi, d.li, d.k.y.wong, and adoptoelectrochemical aptamer based on a 3D flow-like TiO₂-MoS₂-gold nanoparticle heterostructure for detection of kanamycin,Biosens Bioelectron.112(2018)193–201]。

In a third aspect, the present invention provides a method for preparing a photoelectrochemical sensor for kanamycin detection, comprising the following steps: making CuPi/Ti₃C₂Forming a film on the surface of a glassy carbon electrode by using a QDs composite material, and then forming a film on CuPi/Ti₃C₂Incubating Au nanoparticles on the surface of the QDs composite material film, incubating kanamycin aptamer DNA, fixing a kanamycin aptamer DNA chain on the surface of an electrode through the interaction of Au-S bonds, and incubating BSA (bovine serum albumin) to block the non-specific binding site of the kanamycin aptamer DNA chain to obtain the photoelectric chemical sensor; the DNA sequence of the kanamycin aptamer is as follows: 5' -HS- (CH)₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3′。

Further, the preparation method is as followsThe implementation is as follows: 1-3mg/mL of CuPi/Ti₃C₂Dripping aqueous solution of QDs composite material on a glassy carbon electrode, naturally drying in the air to form a film, dripping aqueous solution of gold nanoparticles with the concentration of 1-1.5mg/mL on the surface of the electrode, incubating at room temperature for 1-2h, rinsing the glassy carbon electrode with a phosphoric acid buffer solution with the pH value of 7.0-7.4, dripping a kanamycin aptamer DNA solution with the concentration of 0.1-2 mu M on the surface of the electrode, incubating at the temperature of 4-8 ℃ for 10-80min, rinsing the glassy carbon electrode with a phosphoric acid buffer solution with the pH value of 7.0-7.4, rinsing the BSA solution with the mass fraction of 0.3-0.5% on the electrode, and incubating for 5-40 min; the kanamycin aptamer DNA solution and the BSA solution both use a phosphate buffer solution with the pH value of 7.0-7.4 as a solvent. In the preparation process, the volume of the solution dropped on the glassy carbon electrode is determined by the size of the glassy carbon electrode, so that the solvent can completely cover the surface of the glassy carbon electrode.

Further, CuPi/Ti₃C₂The concentration of the QDs composite aqueous solution is 1.5-2.5mg/mL, most preferably 2 mg/mL.

Further, the concentration of the kanamycin aptamer DNA solution is 1.0 to 1.5. mu.M, most preferably 1.0. mu.M.

Further, the incubation time of the kanamycin aptamer DNA solution is 40-60min, most preferably 60 min.

In a fourth aspect, the invention provides the use of the photoelectrochemical sensor in kanamycin detection.

Further, the application includes:

(1) incubating kanamycin standard solutions with different concentrations on the surface of the photoelectrochemical sensor, testing the response of photocurrent in a phosphate buffer solution with the pH value of 7.0-7.4, and establishing a standard curve of a logarithmic function of the photocurrent intensity and the concentration of the kanamycin standard solution;

(2) incubating a kanamycin solution to be detected on the surface of the photoelectrochemical sensor under the same condition as the step (1), then testing the photocurrent response in a phosphate buffer solution with the pH value of 7.0-7.4, and obtaining the concentration of the kanamycin solution to be detected according to the measured photocurrent intensity by utilizing the standard curve of the step (1);

the solvents of the kanamycin standard solution and the kanamycin solution to be detected are phosphate buffer solutions with pH of 7.0-7.4.

In the application process, the volume of the solution dropped on the glassy carbon electrode is determined by the size of the glassy carbon electrode, the solvent is required to be capable of completely covering the surface of the glassy carbon electrode, and the dropping volumes of different solutions are kept unchanged.

Further, the incubation time of the kanamycin solution is 5-40min, preferably 30-35min, most preferably 30 min.

Further, the photocurrent response was tested in a phosphate buffer solution at pH 7.4.

Further, the photocurrent test conditions were: an external potential of 0.15-0.2V, a 300W xenon lamp light source.

In the invention, the photocurrent intensity increases with the increase of the concentration of the kanamycin solution, and the good linear response is realized in the range of 1pM-10000pM of kanamycin concentration.

The invention synthesizes CuPi/Ti₃C₂The QDs composite material has the sensitive detection characteristic on kanamycin and has wide application prospect in medical use.

Compared with the prior art, the invention has the beneficial effects that:

1. will be based on CuPi/Ti of p-n junction₃C₂QDs heterostructures are used as photoanodes for Photoelectrochemical (PEC) bioanalysis.

2. CuPi/Ti prepared by the invention₃C₂The QDs composite material has good energy level matching, and the rapid electron transfer provides higher sensitivity for the detection of kanamycin.

3. The invention utilizes CuPi/Ti₃C₂The photoelectrochemical sensor prepared from the QDs composite material is applied to kanamycin detection, has good sensitivity, and has good linear response in the range of 1-pM-10000-pM.

Drawings

FIG. 1 is a photocurrent response as a function of CuPi/Ti₃C₂Curves of QDs composite concentration change.

Figure 2 is a plot of photocurrent response as a function of kanamycin incubation time.

FIG. 3 is a plot of photocurrent response as a function of aptamer DNA concentration.

Figure 4 is a plot of photocurrent response as a function of aptamer DNA incubation time.

Figure 5 is a plot of photocurrent response as a function of pH for the kanamycin test system.

FIG. 6 is a plot of photocurrent response versus kanamycin concentration and a linear correlation coefficient plot.

Fig. 7 is SEM and TEM images of the CuPi prepared in example (a is an SEM image of the CuPi, b is a high magnification SEM image of the CuPi, c is a TEM image of the CuPi, and d is a high magnification TEM image of the CuPi).

Detailed Description

The following detailed description of the preferred embodiments of the present invention is provided in connection with the specific embodiments to which the invention pertains, and is intended to be illustrative of, but not limiting to.

Example 1

1. Synthesis of CuPi, comprising the following steps:

step (1): 0.3261g of Cu (NO)₃)₂Dissolve in 3mL of ultrapure water and record as solution a.

Step (2): 3mL of ethanol, 18mL of isooctane and 6mL of n-butanol are respectively taken to be put in a beaker, evenly stirred, then 1.65g of SDBS is added, and ultrasonic treatment is carried out for 10min after full mixing, and the solution is marked as solution b.

And (3): and (3) after the solution b prepared in the step (2) is subjected to ultrasonic treatment, adding the solution a prepared in the step (1) into the solution b by using a pipette, and continuously performing ultrasonic treatment for 10min to obtain a solution c.

And (4): 0.1079g of NaH₂PO₄Dissolving in 3mL of ultrapure water, slowly adding the solution into the solution c prepared in the step (3) by using a syringe, and ensuring that the solution is subjected to ultrasonic treatment for 30min in an ice bath environment.

And (5): washing the product obtained after the reaction in the step (4) with water twice and ethanol once for multiple times until the supernatant is free of foam, and freeze-drying the precipitate. CuPi was obtained, and SEM and TEM images thereof are shown in FIG. 7.

2、Ti₃C₂The synthesis of QDs is carried out as follows:

the first step is as follows: preparation of Ti₃C₂Nanosheets, comprising the steps of:

step (1): LiF (0.5g) was dissolved in HCl (9M, 10mL) at room temperature to obtain a LiF/HCl solution.

Step (2): adding Ti within 5 minutes₃AlC₂(MAX phase, 0.5g) was slowly added to the LiF/HCl solution prepared in step (1) above, giving a suspension.

And (3): the suspension prepared in step (2) was stirred at 35 ℃ for 24 hours.

And (4): the product obtained in step (3) was washed with ultrapure water by centrifugation (3500rpm, 5 minutes) until the pH of the filtrate reached 6.0, to obtain a precipitate.

And (5): taking out the precipitate obtained in the step (4) and adding the precipitate into ultrapure water to obtain Ti₃C₂Suspension (10 mgmL)^-1，30mL)。

And (6): ti obtained in the step (5)₃C₂The suspension was sonicated for 30 minutes under a nitrogen atmosphere.

And (7): finally, Ti obtained in the step (6)₃C₂The suspension was centrifuged at 7500rpm for 20 minutes to collect Ti₃C₂And (3) a supernatant of the nanosheets.

The second step is that: preparation of Ti₃C₂QDs, the procedure is as follows:

step (1): taking 10ml of the prepared₃C₂Adding 0.2mL of PEI (polyethyleneimine) into the supernatant of the nanosheet in a polytetrafluoroethylene inner container, and stirring for 2 hours to obtain a suspension.

Step (2): the suspension obtained in step (1) was purged with nitrogen for 30 minutes.

And (3): and (3) putting the reaction kettle into an oven, and heating for 36 hours at 120 ℃ to obtain a solution.

And (4): finally, filtering the solution reacted in the step (3) by using a filter membrane of 0.22 mu m to obtain Ti₃C₂QDs solutions.

3. Preparation ofCuPi/Ti₃C₂QDs composites, the procedure is as follows:

step (1): 20mg of the CuPi prepared above was dispersed in 10mL of Ti prepared₃C₂And (3) carrying out ultrasonic treatment on the QDs solution for 5min under the ultrasonic power of 500W to obtain a solution.

Step (2): stirring the solution of the step (1) at room temperature at 300rpm for 30min, centrifuging at 5000rpm, and freeze-drying the precipitate to obtain CuPi/Ti₃C₂QDs composites.

Example 2:

the CuPi/Ti prepared in example 1 is added₃C₂The QDs composite material was prepared into aqueous solutions of different concentrations (1mg/mL, 1.5mg/mL, 2mg/mL, 2.5mg/mL, 3mg/mL), 10. mu.L of each solution was dropped on a glassy carbon electrode (3 mm. times.3 mm, all the glassy carbon electrodes used in the examples of the present invention have the same size), and after natural drying in the air to form a film, the photocurrent response was measured (under the test conditions: 0.2V applied potential, 300W xenon lamp light source), and the results are shown in FIG. 1.

Example 3:

1. mixing 100mLHAuCl₄After the solution (0.01%, w/v) is boiled, 3.5mL of trisodium citrate solution (1%, w/v) is rapidly injected into the solution under vigorous stirring and stirring is continued for 15 min; next, the heating was stopped, the solution was further stirred for 30 minutes and cooled to turn wine red, and then the solution was centrifuged at a high speed to obtain a precipitate, and 5.8mL of ultrapure water was added to obtain an aqueous solution of gold nanoparticles of 1 mg/mL.

2. 10 uL of 2mg/mL CuPi/Ti₃C₂Dropping the QDs composite material on a glassy carbon electrode, naturally drying in the air to form a film, dropping 10 mu L of 1mg/mL gold nanoparticle aqueous solution on the surface of the electrode, incubating for 1h, rinsing the glassy carbon electrode with a phosphate buffer solution with pH7.4, and then taking 10 mu L of 1 mu M kanamycin aptamer DNA (kanamycin aptamer, DNA sequence: 5' -HS- (CH-CH)₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3', available from shanghai biochemical reagents limited) solution (PH 7.4 phosphate buffer solution as solvent) was dropped on the electrode surface, incubated in a refrigerator at 4 ℃ for 1h, the glassy carbon electrode was rinsed with PH7.4 phosphate buffer solution, and then 10 μ L mass fraction was taken as 0.After incubating a 3% BSA aqueous solution (pH 7.4 phosphate buffered solution) on the electrode for 30min, 10. mu.L 10nM kanamycin solution (pH 7.4 phosphate buffered solution) was incubated on the electrode for 5min, 10min, 15min, 20min, 25min, 30min, 35min, and 40min, respectively. The photocurrent response was measured for different incubation times in phosphate buffered saline at pH7.4 (test conditions: 0.2V applied potential, 300W xenon lamp source), and the results are shown in FIG. 2.

Example 4:

1. the procedure for preparing an aqueous solution of gold nanoparticles was the same as in example 3.

2. 10 uL of 2mg/mL CuPi/Ti₃C₂Dropping the QDs composite material on a glassy carbon electrode, naturally drying in the air to form a film, dropping 10 μ L of 1mg/mL gold nanoparticle aqueous solution on the surface of the electrode, incubating for 1h, rinsing the glassy carbon electrode with a pH7.4 phosphoric acid buffer solution, and then taking 10 μ L of kanamycin aptamer DNA solution (DNA sequence number: 5' -HS- (CH)₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3'; the solvent was PH7.4 phosphate buffer solution) was dropped on the electrode surface (aptamer concentrations were 0.1 μ M, 0.5 μ M, 1 μ M, 1.5 μ M, and 2 μ M, respectively), the different electrodes were incubated in a refrigerator at 4 ℃ for 1 hour, the glassy carbon electrode was rinsed with PH7.4 phosphate buffer solution, then 10 μ L of 0.3% by mass aqueous BSA solution (solvent PH7.4 phosphate buffer solution) was taken on the electrode, after incubation for 30 minutes, 10 μ L of 10nM kanamycin solution (solvent PH7.4 phosphate buffer solution) was then incubated on the electrode surface, and photocurrent responses (applied potential 0.2V, 300W xenon lamp light source) were measured at different aptamer concentrations in phosphate buffer solution at PH7.4, with the results shown in fig. 3.

Example 5:

1. the procedure for preparing an aqueous solution of gold nanoparticles was the same as in example 3.

2. 10 μ L of 2mg/mL CuPi/Ti₃C₂Dropping the QDs composite material on a glassy carbon electrode, naturally drying in the air to form a film, dropping 10 mu L of 1mg/mL gold nanoparticle aqueous solution on the surface of the electrode, incubating for 1h, rinsing the glassy carbon electrode with a phosphoric acid buffer solution with pH7.4, and then taking 10 mu L of 1 mu M kanamycin suitable for useLigand DNA solution (DNA sequence number: 5' -HS- (CH)₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3'; solvent PH7.4 phosphate buffer) was dropped onto the electrode surface, and the glassy carbon electrode was rinsed with PH7.4 phosphate buffer in a refrigerator at 4 ℃ for 10min, 20min, 30min, 40min, 50min, 60min, 70min, and 80min, respectively, then 10 μ L of 0.3% by mass BSA solution (solvent PH7.4 phosphate buffer) was applied to the electrode, and after 30min of incubation, 10 μ L of 10nM kanamycin solution (solvent PH7.4 phosphate buffer) was applied to the electrode surface, and photocurrent responses (applied potential 0.2V, 300W xenon lamp light source) were measured for various incubation times of kanamycin aptamer DNA in phosphate buffer at PH7.4, as shown in fig. 4.

Example 6:

1. the procedure for preparing an aqueous solution of gold nanoparticles was the same as in example 3.

2. 10 μ L of 2mg/mL CuPi/Ti₃C₂Dropping the QDs composite material on a glassy carbon electrode, naturally drying in the air to form a film, dropping 10 mu L of 1mg/mL gold nanoparticle aqueous solution on the surface of the electrode, incubating for 1h, rinsing the glassy carbon electrode with a phosphoric acid buffer solution with pH of 7.4, and then taking 10 mu L of 1 mu M aptamer DNA (DNA sequence: 5' -HS- (CH): 5. mu.L and 1 mu.M₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3'; solvent PH7.4 phosphate buffer solution) solution was dropped on the electrode surface, incubated in a refrigerator at 4 ℃ for 1h, the glassy carbon electrode was rinsed with PH7.4 phosphate buffer solution, then 10 μ L of 0.3% by mass BSA solution (solvent PH7.4 phosphate buffer solution) was applied on the electrode, incubated for 30min, then 10 μ L of 10nM kanamycin solution (solvent PH7.4 phosphate buffer solution) was applied on the electrode surface, and incubated for 30 min. Finally, photocurrent responses ( pH 5, 6, 7, 7.4, 8, 9, respectively, applied potential 0.2V, 300W xenon light source) were tested in phosphate buffered solutions of different pH, and the results are shown in fig. 5.

Example 7

1. The procedure for preparing an aqueous solution of gold nanoparticles was the same as in example 3.

2. 10 μ L of 2mg/mL CuPi/Ti₃C₂The QDs composite material is dropped on a glassy carbon electrode in the airAfter naturally drying to form a film, 10. mu.L of a 1mg/mL aqueous solution of gold nanoparticles was dropped on the electrode surface, incubated for 1 hour, and then the glassy carbon electrode was rinsed with a phosphate buffer solution having a pH of 7.4, followed by 10. mu.L of a 1. mu.M kanamycin aptamer DNA solution (DNA sequence number: 5' -HS- (CH)₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3'; solvent PH7.4 phosphate buffer solution) on the electrode surface, incubating for 1h in a refrigerator at 4 ℃, rinsing the glassy carbon electrode with PH7.4 phosphate buffer solution, then taking 10 μ L of BSA solution with 0.3% mass fraction (solvent PH7.4 phosphate buffer solution) on the electrode, incubating for 30min, and then incubating for 10 μ L of kanamycin solutions (0pM, 1pM, 5pM, 10pM, 50pM, 100pM, 1000pM, 10000pM, solvent PH7.4 phosphate buffer solution) with different concentrations on the electrode surface, and incubating for 30 min. Finally, the photocurrent response (applied potential 0.2V, 300W xenon lamp light source) was tested in a phosphate buffer solution at ph7.4, and the results are shown in fig. 6, showing: the sensor has good sensitivity, the photocurrent intensity is increased along with the increase of the kanamycin concentration, and the sensor has good linear response and linear correlation coefficient R in the range of 1-pM-10000-pM kanamycin concentration²＝0.9909。

The foregoing detailed description of the preferred embodiments of the invention. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Experiments and technical solutions, which can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the prior art according to the concept of the present invention, should be within the scope of protection determined by the claims.

Claims (10)

1. CuPi/Ti₃C₂The preparation method of the QDs composite material comprises the following steps:

step (1): mixing CuPi and 10-15mg/mLTi₃C₂Mixing the QDs water solution according to the mass-volume ratio of 2:1-4:1, and carrying out ultrasonic treatment for 5-10min under the ultrasonic power of 150-300W to obtain a mixed solution;

step (2): stirring the mixed solution in the step (1) at the rotating speed of 300-500rpm at room temperature for 20-30min, then centrifuging at 3500-₃C₂QDs composites.

2. A photoelectrochemical sensor for kanamycin detection, which is characterized in that CuPi/Ti prepared by the preparation method of claim 1 is sequentially loaded on a glassy carbon electrode from bottom to top₃C₂QDs composite material, gold nanoparticles, kanamycin aptamer DNA and BSA; the DNA sequence of the kanamycin aptamer is as follows: 5' -HS- (CH)₂)₆-TGG-GGG-TTG-AGG-CTA-AGC-CGA-3′。

3. A method of making a photoelectrochemical sensor for kanamycin detection according to claim 2, comprising the steps of: making CuPi/Ti₃C₂Forming a film on the surface of a glassy carbon electrode by using a QDs composite material, and then forming a film on CuPi/Ti₃C₂And incubating Au nano particles on the surface of the QDs composite material film, incubating kanamycin aptamer DNA, fixing a kanamycin aptamer DNA chain on the surface of an electrode through the interaction of Au-S bonds, and incubating BSA (bovine serum albumin) to block the non-specific binding site of the kanamycin aptamer DNA chain to obtain the photoelectric chemical sensor.

4. The method of claim 3, wherein: the preparation method is implemented as follows: 1-3mg/mL of CuPi/Ti₃C₂Dripping aqueous solution of QDs composite material on a glassy carbon electrode, naturally drying in the air to form a film, dripping aqueous solution of gold nanoparticles with the concentration of 1-1.5mg/mL on the surface of the electrode, incubating at room temperature for 1-2h, rinsing the glassy carbon electrode with a phosphoric acid buffer solution with the pH value of 7.0-7.4, dripping a kanamycin aptamer DNA solution with the concentration of 0.1-2 mu M on the surface of the electrode, incubating at the temperature of 4-8 ℃ for 10-80min, rinsing the glassy carbon electrode with a phosphoric acid buffer solution with the pH value of 7.0-7.4, rinsing the BSA solution with the mass fraction of 0.3-0.5% on the electrode, and incubating for 5-40 min; the kanamycin aptamer DNA solution and the BSA solution both use a phosphate buffer solution with the pH value of 7.0-7.4 as a solvent.

5. The method of claim 4, wherein: CuPi/Ti₃C₂The concentration of the QDs composite aqueous solution is 1.5-2.5mg/mL, most preferably 2 mg/mL.

6. The method of claim 4, wherein: the concentration of kanamycin aptamer DNA solution is 1.0-1.5. mu.M, most preferably 1.0. mu.M.

7. The method of claim 4, wherein: the incubation time of the kanamycin aptamer DNA solution is 40-60min, most preferably 60 min.

8. Use of the photoelectrochemical sensor of claim 2 for kanamycin detection.

9. The application of claim 8, wherein the application comprises:

(1) incubating kanamycin standard solutions with different concentrations on the surface of the photoelectrochemical sensor, testing the response of photocurrent in a phosphate buffer solution with the pH value of 7.0-7.4, and establishing a standard curve of a logarithmic function of the photocurrent intensity and the concentration of the kanamycin standard solution;

(2) incubating a kanamycin solution to be detected on the surface of the photoelectrochemical sensor under the same condition as the step (1), then testing the photocurrent response in a phosphate buffer solution with the pH value of 7.0-7.4, and obtaining the concentration of the kanamycin solution to be detected according to the measured photocurrent intensity by utilizing the standard curve of the step (1);

the solvents of the kanamycin standard solution and the kanamycin solution to be detected are phosphate buffer solutions with pH of 7.0-7.4.

10. The use of claim 9, wherein: the incubation time of the kanamycin solution is 5-40min, preferably 30-35min, most preferably 30 min.

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