Label-Free Electrochemiluminescence Aptasensor for Highly Sensitive Detection of Acetylcholinesterase Based on Au-Nanoparticle-Functionalized g-C3 N4 Nanohybrid

A feasible label-free electrochemiluminescence (ECL) aptasensor that uses an Au-nanoparticle-functionalized g-C3N4 nanohybrid (Au-g-C3N4 NH) as the luminophore was constructed for highly sensitive acetylcholinesterase (AChE) detection. The sensor was fabricated by successively modifying a glassy carbon electrode with Au-g-C3N4 NH and thiol-modified AChE-specific aptamers. In the presence of AChE, the ECL signal decreased significantly, because AChE could hydrolyze the substrate acetylthiocholine to generate acetic acid, which could react with the co-reactant triethylamine (Et3N), leading to evident consumption of the co-reactant. The ECL response of the aptasensor was linearly proportional to the concentration of AChE ranging from 0.1 pg/mL to 10 ng/mL, with a detection limit of 42.3 fg/mL (S/N=3). This novel ECL sensing strategy demonstrated a highly sensitive and selective method for AChE detection and was expected to possess potential applications in clinical diagnosis and biomedical technology.