DNA Electrochemical Sensor Based on PbSe Nanoparticle for the Sensitive Detection of CaMV35S Gene Sequence

PbSe nanoparticle surface modified with cetyltrimethylammonium bromide (CTAB) was synthesized with a hydrothermal route. PbSe nanoparticle/chitosan (CHIT) composite films were prepared on the carbon paste electrode (CPE) and characterized by SEM and electrochemical methods. The immobilization and hybridization of DNA on the composite films were investigated by electrochemical impedance spectroscopy and cyclic voltammetry (CV). PbSe nanoparticle/CHIT composite matrix has some advantages, such as large ratio surface area, good biocompatibility, and good film-forming ability, and can markedly enhance the immobilization of DNA. Differential pulse voltammetry (DPV) was used to the sensitive detection of the hybridization of DNA with methylene violet (MV) as the indicator. This DNA electrochemical sensor can differentiate the completely complementary DNA sequence and the 2-base mismatched DNA sequence, indicating a good selectivity. The specific sequence related to CaMV35S promoter gene in some transgenic plants was satisfactorily detected using this DNA electrochemical sensor with the detection range from 5.0 × 10−11 to 5.0 × 10−6 M and the detection limit of 1.6 × 10−11 M.