A sensitive sandwich-type immunosensor for the detection of MCP-1 based on a rGO-TEPA-Thi-Au nanocomposite and novel RuPdPt trimetallic nanoalloy particles

Abstract A novel electrochemical immunosensor was proposed for the detection of monocyte chemoattractant protein-1 (MCP-1), a biomarker of cardiovascular disease. Due to thionine (Thi) possessing electroactive redox properties, a one-step approach was utilized to synthesize a reduced graphene oxide-tetraethylene-thionine-Au (rGO-TEPA-Thi-Au) nanocomposite at room temperature using the synergistic effect of Thi and rGO-TEPA towards HAuCl 4 . We obtained the excellent matrix material, which immobilized more primary antibody MCP-1-Ab 1 on rGO-TEPA on a modified glassy carbon electrode (GCE). To further enhance the sensitivity of the sensor, a novel signal generation and amplification strategy was developed for detection. RuPdPt trimetallic nanoalloy particles (RuPdPt TNPs), a novel nanomaterial, were synthesized by a one-pot method, displayed a uniform morphology as well as good electrochemical activity and bound with the secondary antibodies against MCP-1 via the Pt-NH 2 bond. Most importantly, RuPdPt TNPs have a significant ability to catalyze H 2 O 2 to produce an electron. The electrochemical signal was highly amplified because the electrochemical signal was primarily derived from the synergistic catalysis of H 2 O 2 by RuPdPt TNPs and recorded by chronoamperometry. Under the optimal conditions, this newly designed biosensor exhibited sensitive detection of MCP-1 in the range from 20 fg mL −1 to 1000 pg mL −1 , with a detection limit of 8.9 fg mL −1 (based on a S/N = 3). Additionally, the designed immunosensor showed acceptable selectivity, reproducibility and stability. This immunosensor is a promising strategy for analyzing clinical serum samples in the future.