A DNA Electrochemical Biosensor Using The Natural Active Micromolecules As Electrochemical Hybridization Indicator

DNA electrochemical biosensors have received much attention due to the high sensitivity, specific, rapid response, easy handling, compatibility with miniaturization technology, and low cost. The keys to a successful electrochemical biosensor are the sensitivity of the hybridization indicator. This article study the voltammetric behavior of the natural active micromolecules and establish differential pulse voltammetry for the determination of them on glassy carbon electrode; investigate the interaction between the natural active micromolecules and DNA using voltammetry and spectroscopy; select high sensitive and specific hybridization indicators from the natural active micromolecules for DNA electrochemical biosensors.In phosphate buffer solution (pH 4.0), the voltammetric behavior of aloe-emodin may be a quasi-reversible double electron and double proton transfer at the glassy carbon electrode.The peak current is proportional to the concentration of aloe-emodin over the range of 5×10-8～2×10^-7 M. The detection limit is 3×10^-8 M (S/N=3). The electrochemical study showed that the interaction mode is mainly intercalative binding in pH 7.4 phosphate buffer solution. The UV-Vis spectroscopic study further demonstrated the above results. Through the electrochemical parameters such as charge transfer coefficientαand standard electron transfer rate constant ks in the absence and presence DNA, it was found that the reaction of aloe-emodin with DNA forms an electrochemical active supramolecular complex. Using the natural active micromolecule as electrochemical hybridization indicator, DNA electrochemical biosensor can successful discriminate single- and double-base-mismatched DNAs from fully matched target DNA. When the concentration of the complementary DNA is between 0.1～10μg/ml, the variance signal of oxidation peak current of indicator before and after hybridization is linear with their concentrations. The linear regression equation is expressed as△I p(μA)=0.005840C(μg/ml)+ 0.7753, r=0.9982. The...