Microplate electrochemical DNA detection for phosphinothricin acetyltransferase gene sequence with cadmium sulfide nanoparticles

An electrochemical DNA detection method for the phosphinothricin acetyltransferase (PAT) gene sequence from the transgenetic plants was established by using a microplate hybridization assay with cadmium sulfide (CdS) nanoparticles as oligonucleotides label. The experiment included the following procedures. Firstly target PAT ssDNA sequences were immobilized on the polystyrene microplate by physical adsorption. Then CdS nanoparticle labeled oligonucleotide probes were added into the microplate and the hybridization reaction with target ssDNA sequences took place in the microplate. After washing the microplate for three times, certain amounts of HNO3 were added into the microplate to dissolve the CdS nanoparticles anchored on the hybrids and a solution containing Cd2+ ion was obtained. At last differential pulse anodic stripping voltammetry (DPASV) was used for the sensitive detection of released Cd2+ ion. Based on this principle a sensitive electrochemical method for the PAT gene sequences detection was established. The voltammetric currents of Cd2+ were in linear range with the target ssDNA concentration from 5.0 × 10− 13 to 1.0 × 10− 10 mol/L and the detection limit was estimated to be 8.9 × 10− 14 mol/L (3σ). The proposed method showed a good promise for the sensitive detection of specific gene sequences with good selectivity for the discrimination of the mismatched sequences.