Cerium Oxide/Polypyrrole Nanocomposite as the Matrix for Cholesterol Biosensor

A nanocomposite comprising cerium oxide nanoparticles (CeO2 NPs) and polypyrrole (PPy) was fabricated onto a microelectrode for cholesterol sensing application. The cholesterol oxidase (ChOx) was immobilized on the CeO2 NPs/PPy/electrode by the physical adsorption route. The structure and morphology of the CeO2 NPs/PPy nanocomposite were characterized by X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. Results showed that the ChOx/CeO2 NPs/PPy/electrode was linearly related with cholesterol in the range of 50 to 500 mg/dL. The sensitivity of ChOx/CeO2 NPs/PPy/electrode was 5.7 × 10 − 6 mA/mg⋅dL−1. The optimal parameters, including pH value and temperature, and selectivity, storage stability, and reproducibility of ChOx/CeO2 NPs/PPy/electrode were investigated.

Investigating the Nanocomposite Thin Films of Hematite α-Fe2O3 and Nafion for Cholesterol Biosensing Applications

Nanocomposite materials are multi-phase materials, usually solids, which have two or more component materials having different chemical and physical properties. When blended together, a newer material is formed with distinctive properties which make them an eligible candidate for many important applications. In the present study, thin films of nafion (polymer) and hematite or α-Fe2O3 (nanoparticles) nanocomposite is fabricated on indium tin oxide (ITO) coated glass substrates, due to its enhanced ionic conductivity, for cholesterol biosensor applications. Scanning electron microscopy and Atomic force microscopy revealed the formation of nanorod structured α-Fe2O3 in the films. The cyclic voltammetry (CV) studies of nafion-α-Fe2O3/ITO revealed the redox properties of the nanocomposites. The sensing studies were performed on nafion-α-Fe2O3/CHOx/ITO bioelectrode using differential pulse voltammetry (DPV) at various concentrations of cholesterol. The enzyme immobilization leaded to the selective detection of cholesterol with a sensitivity of 64.93 × 10−2 μA (mg/dl)−1 cm−2. The enzyme substrate interaction (Michaelis–Menten) constant Km, was obtained to be 19 mg/dl.