Electrophoretically deposited CdS quantum dots based electrode for biosensor application

A platform comprising of electrophoretically prepared thioglycolic acid (TGA) capped cadmium sulfide (CdS) quantum dots (QDs) deposited onto an indium tin oxide (ITO) coated glass plate has been utilized for covalent immobilization of cholesterol oxidase for application to a cholesterol sensor. The presence of TGA capped CdS in the nano regime has been confirmed through a UV-visible study. The electrophoretically deposited Nano-CdS/ITO electrode characterized using transmission electron microscopy (TEM), X-ray diffraction, scanning electron microscopy (SEM) and Fourier transform infra-red (FT-IR) techniques indicates the presence of a hexagonal nanocrystalline homogeneous structure on the ITO surface. The results of electrochemical response studies conducted using this CdS QDs based cholesterol sensor reveal a low detection limit (1.87 mg dl−1) and high sensitivity (2.87 μA/mg dl−1/cm2), a low value of Michaelis–Menten constant (Km) (0.22 mM) reveals high enzyme affinity. This novel quantum dot based cholesterol biosensing electrode has implications for the development of other important biosensor applications.