An electrochemical biosensor based on graphene intercalated functionalized black phosphorus/gold nanoparticles nanocomposites for the detection of bacterial enzyme

Abstract

Sortase A (Srt A) is a key enzyme that catalyzes the covalent anchoring of surface proteins to the bacterial cell wall and plays a dominant role in the late stage of Gram-positive bacterial infections. Achieving activity detection of Srt A and inhibitors screening is important for the treatment of Gram-positive bacterial infections and novel antibacterial drugs research. Here, an electrochemical sensor pattern is proposed. Black phosphorus (BP) is a novel graphite-like two-dimensional material with excellent electrochemical properties. However, the extremely poor environmental stability limits its practical application. The surface modification of BP using graphene oxide (GO) significantly improves the stability, and obtained partially reduced graphite oxide functionalized BP composites combine both electrical conductivity and stability. In this paper, we develop an electrochemical biosensor based on partially reduced graphite oxide functionalized BP /gold nanoparticles (p-rGO-BP/AuNPs) nanocomposites for detecting Srt A activity. The assay utilizes two peptide chains, P1 (CLPETG) and P2 (GGGGG), which can be linked by the presence of Srt A. At the same time, the process is monitored by differential pulse voltammetry (DPV). The sensor showed good selectivity and stability with a linear dynamic range of 1 pM-100 nM and a detection limit (LOD) of 0.65 pM. In addition, the method was successfully used to detect Srt A in complex samples and estimate the half-inhibitory concentration (IC50) of Srt A inhibitors (curcumin, dihydromyricetin and rutin).