Amperometric cholesterol biosensor based on reduction graphene oxide-chitosan-ferrocene/platinum nanoparticles modified screen-printed electrode

Cholesterol is a waxy steroid metabolite substance and plays an important role in the brain, nervous, and immune systems of humans. The level of cholesterol in human serum has become an important index for clinical diagnosis and prevention of cardiovascular disease. In this study, a highly sensitive electrochemical biosensor for cholesterol measurement has been developed based on reduced graphene oxide-chitosan-ferrocene carboxylic acid/platinum nanoparticle (RGO-CS-Fc/Pt NPs) modified screen-printed carbon electrode (SPCE). Under the effect of cholesterol oxidase (CHOD) and cholesterol esterase (CHER), the cholesterol was oxidized to generate hydrogen peroxide (H₂O₂), which can be disintegrated into H₂O with the synergistic catalysis of RGO-CS-Fc/Pt NPs and produce the redox response current of H₂O₂ that could be determined by electrochemical amperometric (i-t) method. The prepared cholesterol biosensor was achieved by integrating of the high electrocatalytic efficiency of Pt NPs, high electronic conductivity and large surface area of RGO, the reversible electrochemical behavior of Fc, and good biocompatibility of CS. The measured of redox response current and cholesterol concentration have a good linearity in the range of 0.5–4.0 mg/mL, low detection limit of 5.70 μg/mL (S/N = 3), and good sensitivity of 0.871 nA/mM/cm². Moreover, the RGO-CS-Fc/Pt NPs cholesterol biosensor exhibited excellent specificity, acceptable reproducibility, and higher recoveries in the detection of clinical serum samples, showing great potential for clinical diagnosis.