Immobilizing DNA on Cetyltrimethyl Ammonium Bromide Cationic Membrane for the Detection of Specific Gene Related to NPT II

Abstract

Carbon paste electrode (CPE) was fabricated using solid paraffin as binder. Cetyltrimethyl ammonium bromide (CTAB) was selfassembled on the surface of the CPE to form compact CTAB monolayer with high density of positive charges oriented outside. In weak alkaline medium, both ssDNA and dsDNA could be immobilized on the CTAB/CPE via electrostatic adsorption. The immobilized ssDNA could selectively hybridize with its complementary DNA sequence. The optimization of the factors affecting the property of CPE, stability of self-assembled CTAB, immobilization of ssDNA and electrochemical detection of the hybridization were monitored by cyclic voltammetry and differential pulse voltammetry using methylene blue or K₃Fe(CN)₆ as indicator. This kind of DNA biosensor was successfully used to detect the gene sequence related to the exogenous NPT II gene from the transgenic cole with a detection limit of 1.0 × 10^-8 M. Two basemismatch gene sequence could also be recognized by this method.