Lipopolysaccaride-binding peptides modified Au electrode for the sensitive detection of lipopolysaccharide in water

Lipopolysaccaride(LPS) is the main structural component of the outer membrane of Gram-negative bacteria and causes serious harm to people's health. Thus, in-time detection of LPS in environment is required. Herein, a new LPS electrochemical detection method was developed by using ferricenecarboxylic acid (FCA)-labeled LPS-binding peptide as biomolecular recognition element and electrochemical signal. Au nanoparticles were assembled on 1,6-hexanedithiol modified Au electrode through sulfhydryl groups, and FCA labeled the C-terminal cysteine of LPS-binding peptide was assembled on Au nanoparticles to achieve its immobilization on the electrode surface. In presence of hexaammineruthenium(II/III), a mediated process between ferricene and hexaammineruthenium(II) resulted in electrical signal amplification. The addition of LPS and the its binding with peptides will induce more hexaammineruthenium(III) to access electrode, resulting in the reduction peak current of the hexaammineruthenium(III) and oxidation peak current of ferrocene both increased. The increased electrochemical signals are used to indicate the concentration of LPS. As a result, a highly-sensitive electrochemical method was developed for the rapid determination of LPS. The linear range was from 1.25 to 30 pg mL−1, and the detection limit was 0.039 pg mL−1. It was used in detection of LPS in environmental water samples, and the results consisted with that obtained by Limulus method.