The direct electrochemical detection of Salmonella paratyphi A

Abstract

A novel biosensor based on the direct electrochemistry of Salmonella paratyphi A immobilized on pretreated glassy carbon electrode (PGCE) was established. It was essential that the trans-membrane and trans-wall direct electron transfer of guanine (G) in DNA strand inside viable Salmonella paratyphi A was captured by microwave irradiation for melting double-stranded DNA（dsDNA） into single-stranded DNA (ssDNA). When the microwave irradiation condition reached 100 W for 9 s, the oxidation peak current reached maximal levels in pH 6.0 phosphate buffer solution (PBS). Meanwhile the typical surface controlled and irreversible electrode process of G was revealed by cyclic voltammetry (CV) with participation of 2 protons and 2 electrons respectively. In addition, A linear relationship for the oxidation current of G with the logarithm of Salmonella paratyphi A concentration was established with the range from 2.10 × 103 to 2.10 × 106 CFU ∙ mL−1. The rapid quantification of viable Salmonella paratyphi A was achieved based on the direct electrochemical biosensor.