CN110980688B - Based on carbon quantum dots-TiO2Preparation method and application of nanorod electrode - Google Patents

Based on carbon quantum dots-TiO2Preparation method and application of nanorod electrode Download PDF

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CN110980688B
CN110980688B CN201911275540.XA CN201911275540A CN110980688B CN 110980688 B CN110980688 B CN 110980688B CN 201911275540 A CN201911275540 A CN 201911275540A CN 110980688 B CN110980688 B CN 110980688B
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范丽芳
王贵珍
刘雪峰
梁文婷
郭玉晶
董川
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Abstract

The invention belongs to the technical field of photoelectrochemical analysis, and particularly relates to a preparation method and application of a carbon quantum dot-titanium dioxide nanorod electrode. The invention adopts a one-step hydrothermal method to synthesize TiO on FTO conductive glass2Nanorod and depositing carbon quantum dots on TiO by electrochemical deposition method2On the nano-rod/FTO; carbon quantum dot-TiO is sequentially treated by chitosan and glutaraldehyde2Aldehyde-esterifying the surface of the nano-rod/FTO nano-composite electrode; and fixing the amino-modified DNA complementary strand on the surface of the nano composite electrode material, and introducing the polychlorinated biphenyl aptamer onto the electrode through base complementation to prepare the polychlorinated biphenyl photoelectrochemical aptamer sensor. The invention can rapidly detect the polychlorinated biphenyl 77 in the environment in real time by an exonuclease 1 auxiliary circulating signal amplification strategy. The invention adopts a photoelectrochemical method with low background signal to realize the high-sensitivity and high-selectivity detection of the inert molecule polychlorinated biphenyl 77.

Description

Based on carbon quantum dots-TiO2Preparation method and application of nanorod electrode
Technical Field
The invention belongs to the technical field of photoelectrochemical analysis, and particularly relates to a carbon quantum dot-TiO-based material2A preparation method and application of a nanorod electrode.
Background
Polychlorinated biphenyls (PCBs) are a class of environmentally persistent organic pollutants that are mass produced and widely used in a variety of industrial fields due to their excellent chemical stability, thermal stability, low flammability and electrical conductivity. PCBs are various in types, and 209 kinds of similar substances with different structural types can be divided into two categories according to different numbers and positions of chlorine atoms to replace biphenyl: non-ortho-substitution in planar configuration and non-planar ortho-substitution. Generally, planar PCBs are much more toxic than non-planar PCBs. 3,3 ', 4, 4' -polychlorinated biphenyl (polychlorinated biphenyl 77) belongs to the same class of planar PCBs, has dioxin-like properties, binds to aromatic hydrocarbon receptors, and is considered to be a highly toxic dioxin-like compound compared to most other PCBs. Polychlorinated biphenyl 77 not only disturbs the endocrine and reproductive systems of organisms, but also affects thyroid function to cause neurotoxicity, and causes metabolic disorder, growth deformity, growth retardation and the like of the organisms. Therefore, the rapid and accurate evaluation of the content of highly toxic PCBs homologue (polychlorinated biphenyl 77) similar to dioxin is of great significance to the environmental protection and human health.
At present, the methods for detecting polychlorinated biphenyl are mainly gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-mass spectrometry (HPLC-MS), which are conventional instrumental analysis techniques, and although these methods can achieve high resolution and good accuracy, the instruments used are complicated and expensive, and the preliminary treatment of the sample is cumbersome and time-consuming. In addition, enzyme-linked immunosorbent assay using an enzyme or an antibody as a recognition element has been used for the detection of polychlorinated biphenyl. However, the extraction process of antibodies and enzymes is complicated, costly, and has a limited lifetime.
Disclosure of Invention
Aiming at the problems of complex operation, high cost, poor stability and the like of the existing polychlorinated biphenyl 77 detection technology, the invention provides a carbon quantum dot-TiO-based method2The photoelectrochemical analysis method of the nanorod electrode is used for detecting the polychlorinated biphenyl 77 quickly, with low cost, high sensitivity and high selectivity.
In order to achieve the purpose, the invention adopts the following technical scheme:
based on carbon quantum dot-TiO2The preparation method of the nanorod electrode comprises the following steps:
step 1, ultrasonically cleaning an FTO electrode in acetone, ethanol and secondary water in sequence, and naturally drying to obtain a clean FTO electrode;
in the step 2, the step of mixing the raw materials,adding tetrabutyl titanate into a dilute hydrochloric acid solution, stirring, transferring into a high-pressure reaction kettle, and then obliquely leaning a clean FTO electrode conductive surface downwards against the inner container wall of the high-pressure reaction kettle for reaction; after the reaction is finished, taking out the electrode, thoroughly washing the electrode by secondary water, drying the electrode, and calcining the dried electrode in a muffle furnace to obtain TiO2A nanorod electrode;
step 3, adding TiO2The nanorod electrode is placed in citric acid-sodium citrate buffer solution containing carbon quantum dots, and the carbon quantum dots are deposited on TiO by a constant potential deposition method2Preparing carbon quantum dot-TiO on the nanorod electrode2And (4) a nanorod electrode.
Further, the ultrasonic cleaning time in the step 1 is 15-20 min, and the ultrasonic cleaning frequency is 2000-4000 Hz; the volume of the tetrabutyl titanate in the step 2 is 0.1-0.3 mL; the stirring time is 5-15 min; the reaction temperature is 160-180 ℃, and the reaction time is 6-8 h; the inclination angle is 30-70 degrees; the calcination temperature is 450-500 ℃, and the calcination time is 1-2 h; the mass percent of the dilute hydrochloric acid is 18.5%; the concentration of the carbon quantum dots in the citric acid-sodium citrate buffer solution containing the carbon quantum dots in the step 3 is 0.1-0.2 mg/mL; the deposition time of the constant potential deposition is 20min under the potential of-1.1V.
Further, the preparation steps of the carbon quantum dots in the step 3 are as follows:
step 1, placing two graphite rods in parallel in a glass container filled with pure water, electrifying and stirring, and filtering by using slow quantitative filter paper to obtain filtrate;
step 2, centrifuging the filtrate, and filtering out graphite oxide precipitates and graphite particles to obtain a carbon quantum dot aqueous solution;
and 3, concentrating and drying the carbon quantum dot aqueous solution through a rotary evaporator to prepare the powdery carbon quantum dot.
Further, in the step 1 for preparing the carbon quantum dots, the volume of pure water is 600mL, and the distance between two graphite rods is 5-8 cm; the electrified stirring tool is operated by applying a voltage of 50-60V under a direct current power supply and continuously stirring for 120-125 h; the size of the quantitative filter paper is 1-3 mu m; in the step 2, the centrifugal rotating speed is 20000-22000 rpm, and the centrifugal time is 30-45 min; in the step 3, the concentration temperature is 70-80 ℃, and the concentration is carried out to 0.1-0.2 mg/mL;
based on carbon quantum dot-TiO2The nanorod electrode is applied to a photoelectrochemical sensor.
Based on carbon quantum dot-TiO2The preparation method of the photoelectrochemical sensor with the nanorod electrode comprises the following steps:
step 1, taking an exposed area of 1cm2Carbon quantum dot-TiO of2The nano-rod electrode is used for dropping the chitosan solution on the carbon quantum dots-TiO2Drying the surface of the nanorod electrode at a constant temperature of 40-50 ℃; washing with 0.1mol/L NaOH for several times, and drying; dripping glutaraldehyde solution on the surface of the electrode coated with chitosan, reacting for 20-40 min at room temperature, washing with high-purity water and drying;
step 2, dripping 3.0 mu mol/L terminal amino modified DNA to aldehyde group functionalized carbon quantum dot-TiO2Reacting for more than 12h at 4 ℃ on the surface of the nanorod electrode, and washing away the physically adsorbed DNA by using a buffer solution;
step 3, dripping polychlorinated biphenyl 77 aptamer on the electrode treated in the step 2; hybridizing the aptamer and the DNA at 4 ℃, and washing away the non-hybridized aptamer by using a buffer solution; taking bovine serum albumin to block the unbonded aldehyde-based sites, and preparing the carbon quantum dot-TiO-based2A photoelectric chemical sensor with a nanorod electrode.
Further, the DNA sequence of the terminal amino group modification is 5' -TTC-GTA-GCC-CCG-CCT-TTT-TTT-TTT-TT- (CH)2)6–NH2–3′；
The aptamer DNA sequence is 5' -GGC-GGG-GCT-ACG-AAG-TAG-TGA-TTT-TTT-CCG-ATG-GCC-CGT-G- (CH)2 )6–3′；
Further, in the step 1, the chitosan solution is acetic acid-dissolved chitosan, the volume of the chitosan solution is 20-50 mu L, and the concentration of the chitosan solution is 1% w/v; the volume of the glutaraldehyde is 50-80 mu L, and the concentration is 3% v/v;
the concentration of the buffer solution in the step 2 is 0.1mol/L, and the pH value is 7.41 Tris-HCl;
the volume of the polychlorinated biphenyl 77 aptamer in the step 3 is 20-40 mu L, and the concentration is 3.0 mu mol/L; dripping polychlorinated biphenyl 77 aptamer into carbon quantum dot-TiO modified by DNA complementary strand2The hybridization reaction time on the surface of the nanorod electrode is more than 10 hours; the concentration of the buffer solution is 0.1mol/L, and the pH value is 7.41 Tris-HCl; the volume of the bovine serum albumin is 10-20 mu L, and the concentration is 1-2% w/v.
Based on carbon quantum dot-TiO2The application of the photoelectrochemical sensor of the nanorod electrode is applied to photoelectrochemical analysis.
Based on carbon quantum dot-TiO2Photoelectrochemical analysis method of nanorod electrode based on carbon quantum dot-TiO2The photoelectric chemical detection of the nano-rod electrode photoelectric chemical sensor on the polychlorinated biphenyl comprises the following detection steps:
step 1, preparing a series of polychlorinated biphenyl 77 standard solutions with different concentrations;
step 2, using the carbon quantum-based TiO2The nano-rod electrode photoelectrochemical sensor is a working electrode, the platinum sheet is a counter electrode, and the silver-silver chloride electrode is a reference electrode; placing the three electrodes in 0.1mol/L PBS buffer solution with pH value of 7.41 to form a three-electrode system;
step 3, adding exonuclease 1 into a three-electrode system, sequentially adding the polychlorinated biphenyl 77 standard solution prepared in the step 1 into a test system, and reacting with the photoelectrochemical sensor under the auxiliary action of the exonuclease 1; recording photocurrents corresponding to polychlorinated biphenyl 77 with different concentrations by a time-current method by using a xenon lamp light source as an excitation light source, and drawing a standard curve for analyzing the polychlorinated biphenyl 77 according to the change of the photocurrents and the concentration of the polychlorinated biphenyl 77 in a corresponding standard solution;
and 4, adding a to-be-tested sample with unknown concentration of the polychlorinated biphenyl 77 into a testing system, recording the corresponding photocurrent of the to-be-tested sample by adopting the method in the step 3, and substituting the photocurrent into the drawn standard curve to obtain the concentration of the polychlorinated biphenyl 77 in the unknown to-be-tested sample.
Further, the quantity of the exonuclease 1 in the step 3 is 20U; in a test system, the action time of the complex of the exonuclease 1 and the polychlorinated biphenyl 77-aptamer is 120 min; the action time of the polychlorinated biphenyl 77 and the photoelectrochemical sensor is 40 min; when polychlorinated biphenyl 77 with different concentrations is tested by adopting a time-current method, the set voltage is 0V, and the excitation wavelength of visible light is 420 nm.
Compared with the prior art, the invention has the following advantages:
(1) the invention is made of TiO2The nano-rod is used as an electrode substrate material, and carbon quantum dots are deposited on TiO2On the nanorod electrode, the absorption range of the titanium dioxide nanorod is expanded from an ultraviolet region to a visible region through the load of the carbon quantum dots, and meanwhile, the load of the carbon quantum dots enables the carbon quantum dots-TiO2Under the excitation of visible light, the generated photo-generated electrons and holes of the nano-rod are easier to separate quickly, so that the photoelectric conversion efficiency of the photo-active electrode material is effectively improved.
(2) The invention modifies the DNA chain which is complementary with the aptamer at a carbon quantum dot-TiO2Introducing polychlorinated biphenyl aptamer onto the surface of the nanorod electrode through base complementation, under the condition that exonuclease 1 exists, after an analyte polychlorinated biphenyl 77 is added, under the action of the polychlorinated biphenyl 77 and the aptamer, enabling a polychlorinated biphenyl 77-aptamer complex to enter a solution, and shearing an aptamer chain through the exonuclease 1 in the solution to enable the polychlorinated biphenyl 77 to be released into the solution to react with the aptamer on the surface of the electrode again. Here, exonuclease 1 assists the cyclic amplification of the signal, thus producing carbon quantum dot-TiO based2The photoelectrochemical aptamer sensor of the nanorod electrode has extremely high sensitivity to the determination of the polychlorinated biphenyl 77, the detection limit can reach 0.0034ng/L, and the photoelectrochemical aptamer sensor is one of the most sensitive analysis methods for determining the polychlorinated biphenyl 77 reported at present.
(3) The invention adopts a high-sensitivity photoelectrochemistry analysis method to combine with the aptamer, and greatly improves the anti-interference capability of the prepared electrode due to the high affinity and specificity recognition capability of the aptamer to the polychlorinated biphenyl 77 to be detected. The photoelectrochemistry aptamer sensor can selectively identify the polychlorinated biphenyl 77 in interfering substances with 100 times concentration and similar structures, has excellent selectivity, and can be used for detecting the polychlorinated biphenyl 77 in a complex environment system.
Drawings
FIG. 1 is SEM picture of the titanium dioxide nanorod electrode prepared by the invention, a carbon quantum dot and a carbon quantum dot-TiO2TEM image of nanorods; FIG. 2 is a graph showing the selectivity of the photoelectrochemical aptamer sensor prepared according to the present invention to polychlorinated biphenyl 77 and various interferents;
FIG. 3 shows carbon quantum dot-TiO-based material prepared by the present invention2The current-time curve of the photoelectrochemical sensor constructed by the nanorod electrode in 0.1mol/L Tris-HCl buffer solution.
Detailed Description
In order to make the objects, technical solutions and technical effects of the present invention clearer, the following description clearly and completely describes technical solutions in specific embodiments of the present invention, and it is obvious that the described embodiments are a part of preferred embodiments of the present invention, but not all embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
This example provides a carbon quantum dot-TiO2Method for preparing nano-rod electrode
Mono, TiO2The preparation method of the nanorod electrode comprises the following steps:
(1) ultrasonically cleaning the FTO electrode in acetone, ethanol and secondary water for 15min in sequence, and naturally drying; the frequency of ultrasonic cleaning is 2000 Hz;
(2) adding 0.1mL of tetrabutyl titanate into a dilute hydrochloric acid solution, stirring for 5min (the volume ratio of concentrated hydrochloric acid to secondary water is 1:1), transferring into a high-pressure reaction kettle, inclining the cleaned and dried FTO electrode to lean against the inner container wall at 30 ℃ downwards, and reacting for 6h at the temperature of 180 ℃. Taking out the electrode, thoroughly washing with secondary water, drying, placing into a muffle furnace, calcining at 500 deg.C for 1h to obtain TiO2A nanorod electrode; as shown in FIG. 1A, canTo see in situ vertically grown TiO on FTO2Nanorod, and TiO2The nanorods are uniformly distributed on the surface of the FTO electrode in a columnar array, and the diameter of the nanorods is about 200 nm.
Secondly, a preparation method of the carbon quantum dots comprises the following steps:
(1) placing two graphite rods in parallel in a beaker filled with 500mL of pure water, wherein the distance between the two rods is 5cm, applying 60V voltage under a direct current power supply, continuously stirring for 120h, and filtering the obtained solution by using slow quantitative filter paper;
(2) centrifuging the obtained solution at 22000rpm for 30min, and filtering out graphite oxide precipitate and graphite particles;
(3) and (3) concentrating the carbon quantum dots treated in the step (2) to 0.1mg/mL at 80 ℃ by using a rotary evaporator to prepare the carbon quantum dots. As shown in fig. 1B, carbon quantum dots having a size of about 10nm were successfully synthesized.
Three, carbon quantum dot-TiO2Preparation of nanorod electrode
To synthesize TiO2The nanorod electrode is placed in citric acid-sodium citrate buffer solution of a carbon quantum dot of 0.1mg/mL, and the carbon quantum dot is electrodeposited on TiO by a constant potential deposition method at the potential of-1.1V2And (3) depositing the surface of the nanorod electrode for 20 min. As shown in FIG. 1C, it can be seen that TiO2The surface of the nanorod electrode is loaded with a large number of carbon quantum dots with the size of about 10nm, so that the carbon quantum dots-TiO are prepared2And (4) a nanorod electrode.
Example 2
This example provides a carbon quantum dot-TiO2Method for preparing nano-rod electrode
Mono, TiO2The preparation method of the nanorod electrode comprises the following steps:
(1) ultrasonically cleaning the FTO electrode in acetone, ethanol and secondary water for 18min in sequence, and naturally drying; the frequency of ultrasonic cleaning is 3500 Hz;
(2) adding 0.26mL of tetrabutyl titanate into a dilute hydrochloric acid solution, stirring for 10min (the volume ratio of concentrated hydrochloric acid to secondary water is 1:1), transferring into a high-pressure reaction kettle, and tilting the cleaned and dried FTO electrode with the conductive surface facing downwards at 50 DEGThe reaction was carried out for 7h against the inner wall at a temperature of 170 ℃. Taking out the electrode, thoroughly washing with secondary water, drying, placing into a muffle furnace, calcining at 480 deg.C for 1.5h to obtain TiO2And (4) a nanorod electrode.
Secondly, a preparation method of the carbon quantum dots comprises the following steps:
(1) placing two graphite rods in parallel in a beaker filled with 500mL of pure water, wherein the distance between the two rods is 7.5cm, applying 55V voltage under a direct current power supply, continuously stirring for 123h, and filtering the obtained solution by using slow quantitative filter paper;
(2) centrifuging the obtained solution at 21000rpm for 35min, and filtering to remove graphite oxide precipitate and graphite particles;
(3) and (3) concentrating the carbon quantum dots treated in the step (2) to 0.15mg/mL at 75 ℃ by using a rotary evaporator to prepare the carbon quantum dots.
Three, carbon quantum dot-TiO2Preparation of nanorod electrode
To synthesize TiO2The nanorod electrode is placed in 0.15mg/mL aqueous solution of a carbon quantum dot, and the carbon quantum dot is electrodeposited on TiO by a constant potential deposition method at the potential of-1.1V2And (3) depositing the surface of the nanorod electrode for 20 min.
Example 3
This example provides a carbon quantum dot-TiO2Method for preparing nano-rod electrode
Mono, TiO2The preparation method of the nanorod electrode comprises the following steps:
(1) ultrasonically cleaning the FTO electrode in acetone, ethanol and secondary water for 20min in sequence, and naturally drying; the frequency of ultrasonic cleaning is 4000 Hz;
(2) adding 0.3mL of tetrabutyl titanate into a dilute hydrochloric acid solution, stirring for 15min (the volume ratio of concentrated hydrochloric acid to secondary water is 1:1), transferring into a high-pressure reaction kettle, inclining the cleaned and dried FTO electrode with the conductive surface facing downwards at 70 degrees against the wall of an inner container, and reacting for 8h at the temperature of 160 ℃. Taking out the electrode, thoroughly washing with secondary water, drying, placing into a muffle furnace, calcining at 450 deg.C for 2 hr to obtain TiO2And (4) a nanorod electrode.
Secondly, a preparation method of the carbon quantum dots comprises the following steps:
(1) placing two graphite rods in parallel in a beaker filled with 500mL of pure water, wherein the distance between the two graphite rods is 8cm, applying a voltage of 50V under a direct current power supply, continuously stirring for 125h, and filtering the obtained solution by using slow quantitative filter paper;
(2) centrifuging the obtained solution at 20000rpm for 45min, and filtering to remove graphite oxide precipitate and graphite particles;
(3) and (3) concentrating the carbon quantum dots treated in the step (2) to 0.2mg/mL at 70 ℃ by using a rotary evaporator to prepare the carbon quantum dots.
Three, carbon quantum dot-TiO2Preparation of nanorod electrode
To synthesize TiO2The nanorod electrode is placed in 0.2mg/mL aqueous solution of a carbon quantum dot, and the carbon quantum dot is electrodeposited on TiO by a constant potential deposition method at the potential of-1.1V2And (3) depositing the surface of the nanorod electrode for 20 min.
Example 4
This example is based on carbon quantum dot-TiO2Preparation of polychlorinated biphenyl aptamer sensor with nanorod electrode
(1) Taking an exposed area of 1cm2Carbon quantum dot-TiO of2And (3) dripping 40 mu L of chitosan solution on the surface of the nanorod electrode, and drying at a constant temperature of 40 ℃. Thereafter, it was washed several times with 0.1mol/L NaOH and dried. Dripping 50 μ L of 3% glutaraldehyde solution on the surface of the electrode coated with chitosan, reacting at room temperature for 40min, washing with high-purity water, and drying;
(2) dripping 30 mu L of 3.0 mu mol/L DNA complementary strand modified by terminal amino group to aldehyde group functionalized carbon quantum dot-TiO2Reacting on the surface of the nanorod electrode at 4 ℃ for more than 12 hours, and washing away the physically adsorbed DNA by using 0.1mol/L Tris-HCl (pH 7.41) buffer solution;
(3) and (3) dripping 30 mu L of 3.0 mu mol/L polychlorinated biphenyl 77 aptamer on the electrode treated in the step (2). The reaction was carried out at 4 ℃ for 10 hours or more, and the unhybridized aptamer was washed away with a buffer solution of 0.1mol/L Tris-HCl (pH 7.41). Then, 10. mu.L of 1% (w/v) bovine serum albumin was taken to block the unbound aldehydeThe base site is prepared to obtain the carbon quantum dot-TiO2A photoelectric chemical sensor with a nanorod electrode.
Example 5
This example is based on carbon quantum dot-TiO2Preparation of polychlorinated biphenyl aptamer sensor with nanorod electrode
(1) Taking an exposed area of 1cm2Carbon quantum dot-TiO of2And (3) a nanorod electrode, namely dripping 20 mu L of chitosan solution on the surface of the nanorod electrode, and drying at a constant temperature of 40 ℃. Thereafter, it was washed several times with 0.1mol/L NaOH and dried. Dripping 60 mu L of 3% glutaraldehyde solution on the surface of the electrode coated with chitosan, reacting for 40min at room temperature, washing with high-purity water and drying;
(2) dripping 30 mu L of 3.0 mu mol/L DNA complementary strand modified by terminal amino group to aldehyde group functionalized carbon quantum dot-TiO2Reacting on the surface of the nanorod electrode at 4 ℃ for more than 12 hours, and washing away the physically adsorbed DNA by using 0.1mol/L Tris-HCl (pH 7.41) buffer solution;
(3) and (3) dripping 20 mu L of 3.0 mu mol/L polychlorinated biphenyl 77 aptamer on the electrode treated in the step (2). The reaction was carried out at 4 ℃ for 10 hours or more, and the unhybridized aptamer was washed away with a buffer solution of 0.1mol/L Tris-HCl (pH 7.41). Then, taking 15 mu L of 1% (w/v) bovine serum albumin to block the unbound aldehyde sites, and preparing the carbon quantum dot-TiO-based2A photoelectric chemical sensor with a nanorod electrode.
Example 6
This example is based on carbon quantum dot-TiO2Preparation of polychlorinated biphenyl aptamer sensor with nanorod electrode
(1) Taking an exposed area of 1cm2Carbon quantum dot-TiO of2And (3) dripping 50 mu L of chitosan solution on the surface of the nanorod electrode, and drying at a constant temperature of 40 ℃. Thereafter, it was washed several times with 0.1mol/L NaOH and dried. Dripping 80 μ L of 3% glutaraldehyde solution on the surface of the electrode coated with chitosan, reacting at room temperature for 40min, washing with high-purity water, and drying;
(2) dripping 30 mu L of 3.0 mu mol/L DNA complementary strand modified by terminal amino group to aldehyde group functionalized carbon quantum dot-TiO2Nano-rod capacitorOn the polar surface, the reaction was carried out at 4 ℃ for 12 hours or more, and the physically adsorbed DNA was washed away with a buffer solution of 0.1mol/L Tris-HCl (pH 7.41);
(3) 40 mu L of 3.0 mu mol/L polychlorinated biphenyl 77 aptamer is dripped on the electrode treated in the step (2). The reaction was carried out at 4 ℃ for 10 hours or more, and the unhybridized aptamer was washed away with a buffer solution of 0.1mol/L Tris-HCl (pH 7.41). Then, 20 mu L of 1% (w/v) bovine serum albumin is taken to block the unbound aldehyde sites, and the carbon quantum dot-TiO-based material is prepared2A photoelectric chemical sensor with a nanorod electrode.
Example 7
The embodiment provides a carbon quantum dot-TiO-based material2The photoelectric analysis method of the nanorod electrode comprises the following selective investigation steps:
photoelectrochemical analysis method, the selective investigation steps are as follows:
(1) 1ng/L of polychlorinated biphenyl 77, and polychlorinated biphenyl 81, polychlorinated biphenyl 126, bisphenol A, atrazine, simazine and 2,4-D with the concentration 100 times that of the polychlorinated biphenyl 77;
(2) as described for carbon quantum dot-TiO-based2A photoelectrochemical sensor of the nanorod electrode is used as a working electrode, a saturated calomel electrode is used as a reference electrode, a platinum sheet electrode is used as a counter electrode, and 0.1mol/L PBS (pH 7.41) electrolyte solution forms a three-electrode system;
(3) adding 1ng/L of polychlorinated biphenyl 77 and polychlorinated biphenyl 81, polychlorinated biphenyl 126, bisphenol A, atrazine, simazine and 2,4-D interferents with the concentration 100 times that of the polychlorinated biphenyl 77 into the three-electrode system respectively; meanwhile, 20U of exonuclease 1 is added as a signal auxiliary amplification element to perform photocurrent response measurement on the structural analogs and environment coexisting substances respectively, the measurement selectivity of the photoelectrochemical analysis method on polychlorinated biphenyl 77 and other interferents is shown in figure 2, the photoelectrochemical analysis method can be seen in the test of the polychlorinated biphenyl 77 (1 st bar chart), and the sensor can be used for testing the interferents one by one (2 nd to 7 th bar charts). The result shows that the method only has obvious relative change of the photoelectric current when detecting the polychlorinated biphenyl 77. The relative change of photocurrent of other 6 interferentsLess than 10 percent, which shows that the invention provides a carbon quantum dot-based TiO2The photoelectric analysis method of the nanorod electrode has good selective and specific recognition capability on polychlorinated biphenyl 77.
Example 8
The embodiment provides a carbon quantum dot-TiO-based material2The method for analyzing the photoelectric property of the nanorod electrode comprises the following steps of:
based on carbon quantum dots-TiO2The photoelectrochemical sensor of the nanorod electrode is used as a working electrode, the saturated calomel electrode is used as a reference electrode, the platinum sheet electrode is used as a counter electrode and 0.1mol/L PBS (pH 7.41) electrolyte solution forms a three-electrode system, the potential is 0V, the stability of the sensor is tested by switching a light source for multiple times under the illumination of 420nm, as shown in figure 3, the photocurrent density of the sensor is basically kept unchanged under the continuous excitation of the sensor within 1700s, the photoelectric analysis method has better photoelectric stability, and the result shows that the photoelectric analysis method has better stability.
The embodiments are described in detail, but the present invention is not limited to the above embodiments and examples, and various changes and modifications within the knowledge of those skilled in the art may be made without departing from the spirit of the present invention, and the changes and modifications fall within the scope of the present invention.

Claims (8)

1. Based on carbon quantum dot-TiO2The preparation method of the photoelectrochemical sensor with the nanorod electrode is characterized by comprising the following steps of: the method comprises the following steps:
step 1, taking an exposed area of 1cm2Carbon quantum dot-TiO of2The nano-rod electrode is used for dropping the chitosan solution on the carbon quantum dots-TiO2Drying the surface of the nanorod electrode at a constant temperature of 40-50 ℃; washing with 0.1mol/L NaOH for several times, and drying; dripping glutaraldehyde solution on the surface of the electrode coated with chitosan, reacting for 20-40 min at room temperature, washing with high-purity water and drying;
step 2Dripping 3.0 mu mol/L DNA modified by terminal amino to aldehyde group functionalized carbon quantum dot-TiO2Reacting for more than 12h at 4 ℃ on the surface of the nanorod electrode, and washing away the physically adsorbed DNA by using a buffer solution;
step 3, dripping polychlorinated biphenyl 77 aptamer on the electrode treated in the step 2; hybridizing the aptamer and the DNA at 4 ℃, and washing away the non-hybridized aptamer by using a buffer solution; taking bovine serum albumin to block the unbonded aldehyde-based sites, and preparing the carbon quantum dot-TiO-based2A photoelectric chemical sensor with a nanorod electrode.
2. The carbon quantum dot-TiO-based material according to claim 12The preparation method of the photoelectrochemical sensor with the nanorod electrode is characterized by comprising the following steps of: the DNA sequence modified by the terminal amino group is 5' -TTC-GTA-GCC-CCG-CCT-TTT-TTT-TT- (CH)2)6–NH2–3′；
The aptamer DNA sequence:
5′-GGC-GGG-GCT-ACG-AAG-TAG-TGA-TTT-TTT-CCG-ATG-GCC-CGT-G-(CH2)6–3′。
3. the carbon quantum dot-TiO-based material according to claim 12The preparation method of the photoelectrochemical sensor with the nanorod electrode is characterized by comprising the following steps of:
in the step 1, the chitosan solution is acetic acid-dissolved chitosan, the volume is 20-50 mu L, and the concentration is 1% w/v; the volume of the glutaraldehyde is 50-80 mu L, and the concentration is 3% v/v;
the concentration of the buffer solution in the step 2 is 0.1mol/L, and the pH value is 7.41 Tris-HCl;
the volume of the polychlorinated biphenyl 77 aptamer in the step 3 is 20-40 mu L, and the concentration is 3.0 mu mol/L; dripping polychlorinated biphenyl 77 aptamer into carbon quantum dot-TiO modified by DNA complementary strand2The hybridization reaction time on the surface of the nanorod electrode is more than 10 hours; the concentration of the buffer solution is 0.1mol/L, and the pH value is 7.41 Tris-HCl; the volume of the bovine serum albumin is 10-20 mu L, and the concentration is 1-2% w/v.
4. The carbon quantum dot-TiO-based material according to claim 12The preparation method of the photoelectrochemical sensor with the nanorod electrode is characterized by comprising the following steps of: the carbon quantum dot-TiO2The preparation method of the nanorod electrode comprises the following steps:
step 1, ultrasonically cleaning an FTO electrode in acetone, ethanol and secondary water in sequence, and naturally drying to obtain a clean FTO electrode;
step 2, adding tetrabutyl titanate into a dilute hydrochloric acid solution, stirring, transferring into a high-pressure reaction kettle, and then obliquely leaning a clean FTO electrode conductive surface on the inner container wall of the high-pressure reaction kettle downwards to perform reaction; after the reaction is finished, taking out the electrode, thoroughly washing the electrode by secondary water, drying the electrode, and calcining the dried electrode in a muffle furnace to obtain TiO2A nanorod electrode;
step 3, adding TiO2The nanorod electrode is placed in citric acid-sodium citrate buffer solution containing carbon quantum dots, and the carbon quantum dots are deposited on TiO by a constant potential deposition method2Preparing carbon quantum dot-TiO on the nanorod electrode2And (4) a nanorod electrode.
5. The carbon quantum dot-TiO-based material according to claim 42The preparation method of the photoelectrochemical sensor with the nanorod electrode is characterized by comprising the following steps of: the ultrasonic cleaning time in the step 1 is 15-20 min, and the ultrasonic cleaning frequency is 2000-4000 Hz; the volume of the tetrabutyl titanate in the step 2 is 0.1-0.3 mL; the stirring time is 5-15 min; the reaction temperature is 160-180 ℃, and the reaction time is 6-8 h; the inclination angle is 30-70 degrees; the calcination temperature is 450-500 ℃, and the calcination time is 1-2 h; the mass percent of the dilute hydrochloric acid is 18.5%; the concentration of the carbon quantum dots in the citric acid-sodium citrate buffer solution containing the carbon quantum dots in the step 3 is 0.1-0.2 mg/mL; the deposition time of the constant potential deposition is 20min under the potential of-1.1V.
6. The carbon quantum dot-TiO-based material according to claim 52Photoelectrization of nanorod electrodesThe preparation method of the optical sensor is characterized by comprising the following steps: the preparation steps of the carbon quantum dots in the step 3 are as follows:
step 1, placing two graphite rods in parallel in a glass container filled with pure water, electrifying and stirring, and filtering by using slow quantitative filter paper to obtain filtrate;
step 2, centrifuging the filtrate, and filtering out graphite oxide precipitates and graphite particles to obtain a carbon quantum dot aqueous solution;
and 3, concentrating and drying the carbon quantum dot aqueous solution through a rotary evaporator to prepare the powdery carbon quantum dot.
7. The carbon quantum dot-TiO-based material according to claim 62The preparation method of the photoelectrochemical sensor with the nanorod electrode is characterized by comprising the following steps of: the volume of the pure water in the step 1 is 600mL, and the distance between the two graphite rods is 5-8 cm; the electrified stirring tool is operated by applying a voltage of 50-60V under a direct current power supply and continuously stirring for 120-125 h; the size of the quantitative filter paper is 1-3 mu m; in the step 2, the centrifugal rotating speed is 20000-22000 rpm, and the centrifugal time is 30-45 min; in the step 3, the concentration temperature is 70-80 ℃, and the concentration is carried out to 0.1-0.2 mg/mL.
8. Use of the carbon quantum dot-TiO-based material according to claim 12The photoelectrochemical analysis method of the photoelectrochemical sensor of the nanorod electrode is characterized in that: the photoelectrochemical detection of polychlorinated biphenyl comprises the following steps:
step 1, preparing a series of polychlorinated biphenyl 77 standard solutions with different concentrations;
step 2, using the carbon quantum-based TiO2The nano-rod electrode photoelectrochemical sensor is a working electrode, the platinum sheet is a counter electrode, and the silver-silver chloride electrode is a reference electrode; placing the three electrodes in 0.1mol/L PBS buffer solution with pH value of 7.41 to form a three-electrode system;
step 3, adding exonuclease 1 into a three-electrode system, sequentially adding the polychlorinated biphenyl 77 standard solution prepared in the step 1 into a test system, and reacting with the photoelectrochemical sensor under the auxiliary action of the exonuclease 1; recording photocurrents corresponding to polychlorinated biphenyl 77 with different concentrations by a time-current method by using a xenon lamp light source as an excitation light source, and drawing a standard curve for analyzing the polychlorinated biphenyl 77 according to the change of the photocurrents and the concentration of the polychlorinated biphenyl 77 in a corresponding standard solution;
step 4, adding a to-be-tested sample with unknown concentration of polychlorinated biphenyl 77 into a testing system, recording the corresponding photocurrent of the to-be-tested sample by adopting the method in the step 3, and substituting the photocurrent into the drawn standard curve to obtain the concentration of the polychlorinated biphenyl 77 in the unknown to-be-tested sample;
the quantity of the exonuclease 1 in the step 3 is 20U; in a test system, the action time of the complex of the exonuclease 1 and the polychlorinated biphenyl 77-aptamer is 120 min; the action time of the polychlorinated biphenyl 77 and the photoelectrochemical sensor is 40 min; when polychlorinated biphenyl 77 with different concentrations is tested by adopting a time-current method, the set voltage is 0V, and the excitation wavelength of visible light is 420 nm.
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