Test method and system for researching DNA molecule conductivity

Abstract

The invention provides a test method and a system for researching the electric conductivity of a DNA molecule. The system is formed by the combination of a signal generator, a digital oscillograph, an ultramicro integrated double-ring carbon electrode, a micro-current amplifier and a computer; the ultramicro integrated double-ring carbon electrode produces an electrostatic field to induce the polarization of the DNA module along the vector direction of field intensity and form an electropositive end and an electronegative end which are arranged in parallel between an inner ring electrode and an outer ring electrode; after an input signal is sent into the ultramicro integrated double-ring carbon electrode, an output signal is obtained; the output signal is input into the computer after being amplified by the micro-current amplifier, collected by the digital oscillograph, and converted by an A/D; and the electric conductivity of the DNA module can be researched by analyzing the relationship between the input signal and the output signal. The system and the method have the following advantages: the acting force is too small to damage the DNA module; the overall electric conductivity can be acquired; the electron transition process can be monitored in a real-time manner; the behavior of rapid electron transfer can be traced; the quality of the contact point can be prevented from being affected; the surface is easy to renew; and the instruments are simple.

Description

technical field [0001] The invention relates to the technical fields of electroanalytical chemistry, molecular electronic devices and biosensors, in particular to a system and method for studying the conductivity of DNA molecules. Background technique [0002] In recent years, research on the conductivity of deoxyribonucleic acid (DNA) molecules has attracted a lot of attention. Because of its double helix structure, the bases pair with each other and form large conjugated π bonds between the entire molecular chain. When the DNA molecule is subjected to Electrons are generated when ionizing radiation or ultraviolet light is irradiated, and the electrons move along the DNA molecular chain before being captured, causing DNA damage, which in turn interferes with the process of DNA replication or protein production, resulting in abnormalities or death of cells. Recent research results show that ( http: / / www.its.caltech.edu / ~jkbgrp / ), some proteins can send charges along the lo...

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Problems solved by technology

Spectroscopy method (J.Am.Chem.Soc., 2000, 122: 5893; Biochemistry, 2000, 39: 6190; J.Am.Chem.Soc., 2000, 122: 11545) covalently bonds photooxidants in On the DNA chain, light-induced electron transport triggers base oxidation, causing DNA damage to study DNA conductivity. Conductivity of non-DNA molecules as a whole; biochemical method (J.Am.Chem.Soc., 1995, 117:6406; Biochem.Biophys.Res.Commun., 1992, 188:1) inserts a compound into DNA At one end of the helix, guanine is oxidized under light induction, and the DNA is broken at the position of oxidized guanine by treatment with piperidine, and the DNA fragment obtained is observed by radioactivity to study its conduction behavior. The main method of this method is The disadvantage is that this biochemical technique can only observe the final reaction result caused by electron transfer, and cannot monitor the electron transfer process in real time, and cannot study the overall conductivity of DNA molecules; electrochemical methods (Curr.Opin.Chem.Biol., 2001, 5: 209) to study the conductivity of DNA by detecting the electrochemical behavior of electroactive substances on DNA modified electrodes, that is, to select electroactive substances that can specifically bind to DNA molecules as electrochemical probes to adjust the base sequence control Its insertion position on the DNA chain can be used to study the distance between the electroactive substance and the electrode, the base accumulation and the sequence's influence on the charge transfer. The disadvantage of this method is that the electrochemical technique used For cyclic voltammetry, the information that can be provided is limited, and the scanning speed that can be used is relatively small. Even if the fastest known ultrafast voltammetry is used, it is only about 1MHz, and it is impossible to track the fast electron transfer inside the DNA molecule. Electron microscopy (Nature, 1999,398:407) and atomic force microscopy (Chinese patent application number: 200610147822.8), connect the two ends of the metal electrode with a piece of DNA, and directly measure its current-potential relationship. This method is straightforward. But its disadvantage is: since only one DNA is connected to the metal electrode, the quality of the joint between them seriously affects the measurement results. If the connection between the DNA and the electrode is not good, it is possible that the DNA itself is conductive, but the measured The result of insulation, on the contrary, if the electrode substrate used for measurement has a short circuit, it is also possible that the DNA itself is insulated, but the result of conductivity is measured. All in all, the stability and reliability of the result are not good

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