Electrochemical sensor and method for detecting ochratoxin a
An ochratoxin and electrochemical technology, applied in the field of electrochemical analysis, can solve the problems of low sensor detection sensitivity, many detection steps, complex preparation process, etc., and achieve the effects of rapid sensor response, simple detection operation, and high sensitivity
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Embodiment 1
[0046] Example 1: Preparation of nucleic acid aptamer electrochemical sensor
[0047] The present invention immobilizes the nucleic acid aptamer with the MB label on the specific T base and the thiol modification at the 5' end to the surface of the gold electrode as an electrochemical sensor, and the specific steps are as follows. The surface of the gold electrode was polished with alumina powder with a particle size of 0.05 μm, and then the electrode was ultrasonically cleaned with ultrapure water. Using a three-electrode system, at 0.5M H 2 SO 4 In the solution, repeated cyclic voltammetry scanning was performed in the range of -0.35V to 1.55V, and the surface of the gold electrode was electrochemically cleaned. Surface-treated clean gold electrodes were immersed in 50 μL of PBS solution (137mM NaCl, 2.7mM KCl, 10mM NaCl) containing the nucleic acid aptamer (500nM). 2 HPO 4 , 1.75mM KH 2 PO 4 , pH 7.5), let stand at room temperature for 1 hour, and then rinse with ultr...
Embodiment 2
[0048] Example 2: Comparison of the signal response to OTA of electrochemical sensors corresponding to nucleic acid aptamers labeled with MB at different T base positions
[0049] Using the method in Example 1, six kinds of electrochemical sensors were prepared, the difference being that the position of the MB label in the nucleic acid aptamer sequence was different. The different T base positions of the MB marker in the nucleic acid aptamer sequence are T3, T8, T10, T14, T19, and T30, respectively, corresponding to the 3rd, 8th, 10th, 14th, 19th, and 30th bases in the nucleic acid aptamer sequence Base T. By square-wave voltammetry, the sensor measured the peak current signals of MB in the blank sample and the sample solution containing 500 nM OTA, respectively. Such as figure 1 As shown, the electrochemical sensor corresponding to MB labeled on T30, the peak current signal of MB increased significantly in the OTA sample. In the presence of OTA in the electrochemical senso...
Embodiment 3
[0050] Embodiment 3: Electrochemical sensor detects OTA
[0051] According to the method in Example 1, an electrochemical sensor was prepared by using a nucleic acid aptamer labeled with MB at the 30th base T (T30) in the sequence to detect OTA. In square wave voltammetry, with the increase of OTA concentration, the peak current of MB around -0.25V gradually increased. figure 2 The typical square wave voltammetry detection curve results are shown in , and the OTA concentrations corresponding to the curves from low to high are 0, 20, 100, 500, and 2000 nM OTA, respectively. image 3 The relationship between MB peak current and OTA concentration in square wave voltammetry is given. The electrochemical sensor can detect 30 pM OTA. image 3 As shown, the highest detection concentration investigated in the experiment was 3 μM, and the MB peak current signal changed significantly, and the MB peak current value corresponding to 3 μM OTA increased by 112% compared with the MB peak ...
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