Immobilization of bovine hemoglobin on Au nanoparticles/MoS nanosheets - Chitosan modified screen-printed electrode as chlorpyrifos biosensor.

In this paper a quick and disposable electrochemical biosensor based on bovine hemoglobin (BHb) is proposed for the determination of chlorpyrifos (CP). The bioelectrode (denoted as AuNPs/MoS-CS/BHb/SPE) has been designed by immobilizing BHb on the screen printed electrode (SPE) surface modified by gold nanoparticles (AuNPs) and Molybdenum disulfide (MoS) nanosheets - chitosan (CS) mixture (MoS-CS). Field emission scanning electron microscopy (FESEM) and electrochemical characterization demonstrate the successful grafting of AuNPs/MoS-CS/BHb/SPE. Detailed electrochemical impedance spectroscopy (EIS) analysis and cyclic voltammetry (CV) tests show that the proposed bioelectrode exhibits decent electrochemical properties, such as well conductivity and large specific surface area. In-depth electrochemical analysis reveals the redox reaction occurring on the surface of the bioelectrode and the mechanism that CP binds with BHb forming the thin film to inhibit the peak current. The proposed biosensor exhibits sensitive and stable responses for electrochemical assay of CP ranging from 0.004 μM to 28.52 μM, with a limit of detection (LOD) as 5.6 nM. The electrochemical biosensor passes the repeatability, reproducibility, stability and anti-interference ability test experiments with good performance. The biosensor also shows its credibility for detecting CP in real vegetable samples (Cabbage and Leek) with recovery (%) ranging from 87% to 109%. The proposed biosensor is of great potential application values for detecting CP and the study is of great reference value for the research and development of biosensors for quantitative detection of organophosphate pesticides (OPs).