A novel electrochemical strategy based on porous 3D graphene-starch architecture and silver deposition for ultrasensitive detection of neuron-specific enolase

Abstract

This work was aimed at designing a novel and ultrasensitive electrochemical immunoassay strategy to detect neuron-specific enolase (NSE) with a triple signal amplification strategy. A greatly enhanced sensitive detection of NSE was achieved by using porous three-dimensional graphene-starch architecture (3D-GNS) modified on the immunosensor's surface to construct a unique 3D immunoelectrode, which would greatly accelerate electron transfer and capture more protein molecules. 3D-GNS was prepared with starch as a crosslinking agent and stabilizer, which is biocompatible and environmentally friendly. Aggregation-free gold nanoparticle (AuNP) incorporated ordered mesoporous carbon–silica (OMCSi–Au) with good catalytic activity was synthesized as the tracing tag for labeling signal antibody (Ab₂). After a sandwich-type immunoreaction, the OMCSi–Au labeled Ab₂ was trapped on the surface of the immunosensor, and the high concentration of AuNPs with high dispersion greatly catalyzed the deposition of silver nanoparticles. The deposited silver nanoparticles (AgNPs) could be tested directly with anodic stripping voltammetric analysis (ASV) in potassium chloride solution to monitor the immunoreactions, which greatly enhanced the sensitivity of protein markers with a detection limit of 0.008 pg mL⁻¹, and a linear range of 0.02 pg mL⁻¹ to 35 ng mL⁻¹ for neuron-specific enolase antigen. This proposed immunosensor displayed acceptable accuracy, good stability, and high sensitivity. Good results were also obtained in agreement with the enzyme-linked immunosorbent assay method, which provides greatly promising potential in clinical applications.