An improved amperometric cholesterol biosensor based on cholesterol oxidase nanostructures for pre-diagnosis of myocardial infarction

Cholesterol plays a pivotal role in human health, serving as a crucial biomarker for cardiovascular diseases, including myocardial infarction. This study presents the development of an innovative amperometric cholesterol biosensor that enhances the detection and quantification of cholesterol levels in serum. The biosensor integrates cholesterol oxidase (ChOx) nanoparticles with a modified electrode, leveraging the unique properties of platinum nanoparticles (PtNPs) and graphene nanosheets (GNs) to improve sensitivity and stability. The synthesis of PtNPs was achieved using Camellia sinensis extract, while graphene oxide was reduced to form GNs. At 2.39 mg/mL or above is deemed a biomarker for cardiovascular disorders, peripheral artery disease, heart attack, diabetes mellitus, strokes, and hypertension. The monitoring of serum cholesterol level is therefore very significant. In the present study, an innovative amperometric cholesterol biosensor was constructed by immobilizing nanoparticles of cholesterol oxidase onto a pencil graphite (PG) electrode modified with graphene nanosheets (GNs), platinum nanoparticles (PtNPs), and chitosan (CHIT). At various stages of construction, the modified electrode was characterized by employing electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. The biosensor responded best when run at 0.14Vs^-1 at optimal pH and temperature of 8.0 and 35°C respectively. The biosensor has a wide linear range (0.1mg/mL-7.5 mg/mL), with great sensitivity (0.89 mA cm⁻¹mgmL⁻¹) and a low limit of detection (0.97 mg/mL). This research not only contributes to the field of biosensing but also offers a promising tool for the early diagnosis of cholesterol-related health issues, paving the way for enhanced cardiovascular disease management.