Electrochemical Impedance Biosensor for the Determination of Lipopolysaccharide Using Peptide as the Recognition Molecule

A simple and sensitive electrochemical impedance spectroscopy (EIS) biosensor was designed for the determination of lipopolysaccharide (LPS). The gold nanoparticles (GNPs) were electrochemically deposited on the glassy carbon electrode as a base electrode and the biosensor was fabricated by self-assembling a special peptide (GIGKLHSAGKF) used as molecular recognition onto the GNPs surface according to the Au–S bond. Polyethylene glycol and 6-mercapto-1-hexanol were used to block the remaining sites of the modified electrode surface. When binding of LPS, the biosensor had a good response to different concentrations of LPS and the charge transfer resistance of the biosensor was directly related to the logarithm of LPS concentrations in the range of 0.01 pg mL-1-1.0 ng mL-1 with a limit of detection of 2.0 fg mL-1. The characteristics of the electrochemically deposited GNPs and the optimization concentration and the self-assembly time of peptide, as well as the performance of the EIS biosensors for LPS were investigated. The biosensor was used for real serum sample determination with satisfactory results.