Direct Electrochemistry of Cholesterol Oxidase Immobilized on a Conducting Polymer: Application for a Cholesterol Biosensor

Direct electrochemistry of cholesterol oxidase (ChOx) immobilized on the conductive poly-3',4'-diamine-2,2',5',2 ''-terthiophene (PDATT) was achieved and used to create a cholesterol biosensor. A well-defined redox peak was observed, corresponding to the direct electron transfer of the FAD/FADH(2) of ChOx, and the rate constant (k(s)) was determined to be 0.75 s(-1). Glutathione (GSH) covalently bonded with PDATT was used as a matrix for conjugating AuNPs, ChOx, and MP. simultaneously. MP co-immobilized with ChOx on the AuNPs-GSH/PDATT exhibited an excellent amperometric response to cholesterol. The dynamic range was from 10 to 130 mu M with a detection limit of 0.3 +/- 0.04 mu M.