Electrochemical sensor for detecting lead as well as preparation method and application thereof

An electrochemical and sensor technology, applied in the field of electrochemical sensors for detecting lead and its preparation, can solve the problems of unstable fixation, affecting DNA activity, and easy use of environmentally harmful substances, so as to improve sensitivity, improve detection performance, and improve The effect of sensitivity

Inactive Publication Date: 2014-09-03

HUNAN UNIV

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Problems solved by technology

These methods all have defects such as weak fixation, the use of various affinity substances in...

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Abstract

The invention relates to an electrochemical sensor for detecting lead. The electrochemical sensor comprises a glassy carbon electrode, wherein the glassy carbon electrode is utilized as a working electrode in a tri-electrode system, the surface of a detection end of the glassy cabon electrode is modified by a multi-walled carbon nanotube, nano golden particles are deposited on the multi-walled carbon nanotube, and a sulfydryl-modified capturing probe is connected with the nano golden particles; the electrochemical sensor further comprises an aptamer probe, wherein the aptamer probe and the sulfydryl-modified capturing probe are complementally paired to form a double-chain structure. According to the electrochemical sensor for detecting the lead, the aptamer probe is utilized to cover lead ions so as to be separated from the capturing probe, and during the separation, an electrochemical signal to be detected is generated, so that the purpose of detecting the content of the lead ions in the water body is achieved; the electrochemical sensor has the advantages of high sensitivity, excellent selectivity and stability, and the like.

Application Domain

Material electrochemical variables

Technology Topic

IonSurface modification +8

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Examples

Experimental program(5)

Example Embodiment

[0039] Example 1

[0040] see figure 1 , an electrochemical sensor for the detection of lead ions, comprising a glassy carbon electrode used as a working electrode in a three-electrode system, an aptamer probe, and methylene blue. The surface of the detection end of the glassy carbon electrode is modified with multi-walled carbon nanotubes, nano-gold particles are deposited on the multi-walled carbon nanotubes, and thiol-modified capture probes are connected to the nano-gold particles. When the electrochemical sensor is used to detect lead ions, the aptamer probe and the sulfhydryl-modified capture probe form a double-stranded structure through complementary pairing, and methylene blue (0.1 mM concentration) is embedded in the sulfhydryl-modified capture probe and aptamer probe. in the double-stranded structure formed.

[0041] The concentration of methylene blue can also be 0.1-0.5 mM.

[0042] In the present invention, the capture probe and the aptamer probe can be any amino acid sequence that can form a complementary pair. In order to obtain a stronger electrochemical detection signal, the capture probe of Example 1 is described in SEQ ID NO.1 The nucleotide sequence of , specifically:

[0043] 5'-CACCCACCCAC-SH-3';

[0044] The aptamer probe preferably has the nucleotide sequence described in SEQ ID NO.2, specifically:

[0045] 5'-GGGTGGGTGGGTGGGT-3';

[0046] The "GTGGGT" at the 3' end of the aptamer probe is complementary to the "CACCCA" at the 5' end of the capture probe.

Example Embodiment

[0047] Example 2

[0048] The preparation method of the electrochemical sensor of embodiment 1.

[0049] Polish the surface of the glassy carbon electrode, then wash the surface of the glassy carbon electrode with water, then use nitric acid, acetone, and water to ultrasonically clean it, and finally use a concentration of 10mM Tris-HCl buffer solution (Tris-HCl buffer solution contains 1.0M KCl ) rinsed, dried naturally, and then used for the preparation of electrochemical sensors, the specific preparation method is:

[0050] S1. Carboxylate the multi-walled carbon nanotubes to obtain carboxylated multi-walled carbon nanotubes; the specific steps are:

[0051] The multi-walled carbon nanotubes are immersed in a mixed solution with a volume ratio of 1:3 of hydrogen peroxide and concentrated sulfuric acid (the mass fraction of concentrated sulfuric acid is 98%) (the volume ratio of hydrogen peroxide and concentrated sulfuric acid can also be 1:2 ~4), ultrasonication at a temperature of 50°C for 2.5h (ultrasonic time can be more than 2.5h), then wash with ultrapure water and absolute ethanol to neutrality, filter with suction, and vacuum dry at a temperature of 60°C for 24h .

[0052] S2. Put the carboxylated multi-walled carbon nanotube suspension into N,N-dimethylformamide to prepare a suspension with a concentration of 1.0 mg/mL, and then add the suspension to the detection end of the glassy carbon electrode dropwise surface, air-dried at room temperature to obtain a glassy carbon electrode decorated with multi-walled carbon nanotubes.

[0053] S3. Deposit nano-gold particles on the detection end surface of the multi-walled carbon nanotube-modified glassy carbon electrode by electrochemical deposition to obtain a nano-gold/multi-walled carbon nanotube-modified glassy carbon electrode.

[0054] In the aforementioned electrochemical deposition method, the initial potential of the electrodeposition method is 0V, the sampling interval is 0.1s, and the deposition time is 60s.

[0055] S4, inserting the glassy carbon electrode modified by nano-gold/multi-walled carbon nanotubes into the sulfhydryl-modified capture probe with a concentration of 1.0 μM (the capture probe has the nucleotide sequence described in SEQ ID NO.1), capture The probe is adsorbed on the gold nanometer through chemical reaction and electrostatic adsorption; then it is inserted into a mercaptoethanol solution with a concentration of 2.0 mM, so that the mercaptoethanol blocks the unadsorbed gold nanometer.

[0056] S5. Prepare an aptamer probe solution with a concentration of 1.0 μM complementary to the amino acid sequence of the capture probe (the aptamer probe has the nucleotide sequence described in SEQ ID NO.2) and a methylene blue solution with a concentration of 0.1 mM , to complete the preparation of the electrochemical sensor.

[0057] The glassy carbon electrode modified by multi-walled carbon nanotubes prepared in step S2 and the glassy carbon electrode modified by nano-gold/multi-walled carbon nanotubes prepared in step S3 were scanned by electron microscope respectively. For the scanning results, see figure 2 , 3.

[0058] from figure 2 , 3 It can be seen that the multi-walled carbon nanotubes on the glassy carbon electrode are uniformly dispersed ( figure 2 ), gold nanoparticles spread on multi-walled carbon nanotubes ( image 3 ).

Example Embodiment

[0059] Example 3

[0060] The application of the electrochemical sensor of embodiment 1 in detecting lead ion, concrete detection method is:

[0061] Add the aptamer probe dropwise to the reaction end surface of the glassy carbon electrode of the electrochemical sensor, react at 37°C for 60 minutes, and then drop the methylene blue with a concentration of 0.1mM (the concentration of methylene blue can be 0.1-0.5mM) on the glassy carbon electrode The surface of the reaction end was reacted at 37°C for 20 minutes; then the concentration of lead ions was respectively adjusted to 5.0×10 -11 M~1.0×10 -14 The test solution of M was added dropwise on the surface of the glassy carbon electrode, and after 30 minutes of reaction, it was connected to the electrolytic cell of the three-electrode system, and the current value was detected with Tris-HCl with a pH of 7.4 as the electrolyte solution.

[0062] Figure 4 is the concentration of lead ions are 0M(a), 1.0×10 -14 M(b), 5.0×10 -14 M(c), 1.0×10 -13 M(d), 5.0×10 -13 M(e), 1.0×10 -12 M(f), 5.0×10 -12 M(g), 1×10 -11 M(h) and 5.0×10 -11 The differential pulse voltammetry curve (DPV curve) of the solution to be tested of M(i), Figure 5 is the linear regression equation graph of lead ion concentration and current change, from Figure 4 and Figure 5 It can be seen that the linear regression equation between the concentration of lead ions and the current value is:

[0063] Y=–(7.660±0.363)–(1.035±0.03118)χ

[0064] Wherein, Y is the electric current mean value when lead ion is detected, and unit is A; χ is the natural logarithm of the concentration value of lead ion in the solution to be tested, and unit is M; R 2 =0.994; the lower limit of detection is 4.3×10 -15 M (the lower limit of detection is calculated according to the standard deviation of 3 times the blank sample).

[0065] In Example 3, the electrolyte solution in the electrolytic cell can also be a Tris-HCl buffer solution with a pH of 5.0 to 9.0; the preparation method of the methylene blue solution is as follows: 0.007478 g of methylene blue is dissolved in 100 mL of ultrapure water.

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PUM

Property	Measurement	Unit
Concentration	0.1 ~ 0.5	mM
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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High sensitivity
Improve detection performance

Electrochemical sensor for detecting lead as well as preparation method and application thereof

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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