Sensitive electrochemical sensor for detection of lipopolysaccharide on metal complex immobilized gold electrode

A facile method for detection of lipopolysaccharide (LPS) on metal complex immobilized gold electrode is described. The metal complex modified electrode was constructed from a gold electrode modified with Cu and nitrilotriacetic acid (NTA) complex, which binds to the O-side chain of LPS in gram-negative cells. The electrochemical impedance spectroscopy (EIS) was used to detect interaction of LPS with NTA–Cu complex. The performance of the NTA–Cu sensor was investigated by EIS and a linear relationship was observed between charge transfer resistance (Ret) and LPS concentration in the range of 0.0001–0.1 ng mL−1. The NTA–Cu complex exhibited insignificant binding to DNA, RNA, bovine serum albumin, glucose, and cholesterol whereas LPS interacted strongly in the biological species. Furthermore, the NTA–Cu sensor was easily regenerated from EDTA solution, and the regenerated sensor demonstrated response sensitivities similar to the original sensor with a deviation of only 4%. These findings show that the NTA–Cu modified gold electrode can be used to detect LPS in real-time.