Electrogenerated chemiluminescence from CdS hollow spheres composited with carbon nanofiber and its sensing...

The electrogenerated chemiluminescence (ECL) from nanometre-sized CdS hollow spheres and carbon nanofiber (CdSHS-CNF) nanocomposites in aqueous solution and their sensing applications were studied by entrapping them in carbon paste. The CdSHS-CNF nanocomposites exhibited a peak at -1.02 V (vs. Ag/AgCl) in 0.1 M pH 8.0 PBS containing 20 mM H(2)O(2) during the cyclic sweep between 0 and -1.2 V at 40 mV s(-1). Compared with CdS hollow spheres (CdSHS), carbon nanofiber (CNF) and CdS nanocrystals and carbon nanofiber (CdSNC-CNF) nanocomposites, CdSHS-CNF not only enhanced the electrochemiluminescent intensity but also decreased the ECL starting potentials. Furthermore, by immobilizing cholesterol oxidase (ChOx) on CdSHS-CNF nanocomposites modified electrode, a sensitive and selective method was developed for detection of cholesterol using oxygen as a coreactant which captured more electrons from electrochemically reduced CdSHS-CNF than H(2)O(2). Under optimal conditions, the sensor could be used for the determination of cholesterol from 1 × 10(-6) to 4.4 × 10(-4) M with a correlation coefficient of 0.9991 and a detection limit was 8 × 10(-7) M at 3σ. The unique ECL intensity and stability of CdSHS-CNF would promote the application of nanometre-sized semiconductor hollow spheres based composites in fabricating sensors for chemical and biochemical analysis.