Bioelectrochemical sensor for detecting silver ion and preparation method thereof
A bioelectrochemical and sensor technology, applied in the field of new bioelectrochemical sensors and their preparation, can solve problems such as water source pollution and human hazards, and achieve the effect of wide application prospects
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Embodiment 1
[0021] Example 1: Preparation of Gold Electrode Modified by Template DNA
[0022] Drop 20 μL of piranha solution (concentrated sulfuric acid:hydrogen peroxide = 3:1) on the surface of the gold electrode to be treated for 2 min, rinse with ultrapure water, and blow dry with nitrogen. After the gold electrode was polished on 5000-grit sandpaper for 5 min, it was successively polished to a mirror surface on silk with alumina (particle size: 1 μm, 0.3 μm, 0.05 μm) mortar, and then ultrasonicated in ethanol and ultrapure water. 5 min to remove impurities. Place the treated gold electrode in 0.5 M H 2 SO 4 Cyclic voltammetry scan. Set the scanning voltage range from 0 to 1.55 V, the scanning speed at 100 mV / s, set 20 cycles until the cyclic voltammetry curve is stable, and dry it with nitrogen to obtain a bare gold electrode with a clean surface, which can be used for the modification of thiol DNA. Soak the gold electrode in 1 μM template DNA solution (10 mM Tris-HCl, 10 mM TCEP...
Embodiment 2
[0023] Embodiment two: the flow process of detecting silver ion
[0024] Put the template DNA-modified gold electrode into the solution containing 100 nM primer DNA, 0.5 U / μL BsaBI endonuclease, 0.05 U / μL Bst nucleic acid polymerase, 50 μM dNTPs, 1 × NE buffer 4 (50 mM KAc, 20 mM Tris-HAc (pH 7.9), 10 mM Mg(Ac) 2 ) in the silver ion reaction solution to be tested at 60°C for 7 minutes, rinsed with ultrapure water, and dried with nitrogen to obtain an enzyme-cut gold electrode, which was placed in the electrochemical detection buffer for electrochemical scanning. Related nucleic acid sequences are as follows:
[0025] The sequence of the template DNA is: 5'-CCTACGACTGGATGACGATCCCTACGACTGAAA A A AAAAAA-C 6 -SH -3'
[0026] The primer DNA sequence is: 5'-CAGTCCTAGG-3'
[0027] Parameters related to electrochemical detection and buffer solution: In cyclic voltammetry and chronoelectric experiments, the reaction solution contained 50 μM [Ru(NH 3 ) 6 ] 3+ 10 mM Tris-HCl (pH 7...
Embodiment 3
[0029] Embodiment three: the detection of different concentration silver ions
[0030] Soak the gold electrode modified with template DNA in the reaction solution of different concentrations of silver ions (0 M, 50 pM, 100 pM, 500 pM, 1 nM, 10 nM, 50 nM, 100 nM, 250 nM, 500 nM and 1 μM) In the method, after the double-enzyme reaction, it was placed in the detection buffer and used for electrochemical detection by chronocoulometry.
[0031] Such as figure 2 As shown, as the concentration of silver ions increases, the electrochemical signal obtained by chronocoulometry gradually decreases, because the more silver ions, the more template DNA is cut in the same time, so the electrochemical signal The signal is smaller.
[0032] Plotting the silver ion concentration and the change (decrease) value of the chronoelectricity can be obtained image 3 . in addition, image 3 The inset figure shows that when the concentration of silver ions varies between 10 pM and 100 nM, the diff...
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