An Electrochemical Immunoassay for Lactobacillus rhamnosus GG Using Cu@Cu2O Nanoparticle-Embedded B, N, Co-doped Porous Carbon

In this paper, we have developed a fast and low-cost label-free electrochemical immunosensor for detection of Lactobacillus rhamnosus GG (LGG). The proposed sensor is based on a glassy carbon electrode modified with Cu@Cu2O nanoparticles anchored B, N co-doped porous carbon (BNPC) composite. The copper-derived nanoparticles with multiple valence states undergo dramatic changes in surface areas, conductivity, and actives sites due to their combination with BNPC, resulting in enhanced electrochemical performance. In the amperometric immunoassay, the immune complex of antigen and antibody inhibits the transfer of electrons on the electrode interface, causing a change in the current. Thus the quantitative detection of LGG is achieved. Differential pulse voltammetry (DPV) was performed at a LGG concentration of 102 to 108 colony-forming units CFU mL−1. The immunosensor showed a good linear relationship between the decrease in peak current and the concentration of LGG (R2 = 0.9934), with a short detection time and a detection limit of 12 CFU mL−1. In short, we have developed a highly sensitive electrochemical immunosensor for the specific detection of LGG using the current-mode, label-free immunoassay method evaluated in this study, providing a reliable mean for quantifying probiotics.