Electrochemiluminescence biosensor for cholesterol detection based on AuNPs/l-cys–C60 nanocomposites

Abstract

A sensitive electrochemiluminescence (ECL) biosensor was fabricated for detection of cholesterol based on an anodic ECL of luminol at low potential. First, C₆₀ was functionalized with L-cysteine (L-cys) to obtain an L-cys–C₆₀ composite, which was modified onto the surface of glassy carbon electrodes for adsorbing gold colloidal nanoparticles (AuNPs). Subsequently, cholesterol oxidase (ChOx) was dropped onto the surface of modified electrode to fabricate a cholesterol biosensor. The assembly process was characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and ECL. Under the optimal conditions, the proposed biosensor exhibited a sensitive response to cholesterol in the concentration range from 1.7 × 10⁻⁵ mM to 0.30 mM with the detection limit of 5.7 × 10⁻⁶ mM (S/N = 3). Furthermore, the proposed biosensor has good reproducibility, stability and anti-interferent ability.