Reagentless sensor integrating electrodes, photodetector, and immobilized co-substrate for electrochemiluminescence-based assays

A reagentless and regenerable electrochemiluminescence sensor has been deve loped by immobilizing the Rubpy(3)(2+) complex at the surface of a miniatur ized sensor combining the electrode transducer and the photodetector on the same silicon chip. The immobilization was performed following a two-step p rocedure. The complex was first incorporated in a sol-gel matrix which was ground to a powder. The microparticles thus obtained were then entrapped in a polyhydroxyethyl methacrylate membrane. The sensor was characterized by performing codeine assays with standard and pharmaceutical samples. The det ection limit for codeine was 20 mu M and the sensitivity of the sensor repr esented 20% of the value obtained when the cosubstrate was supplied in solu tion. The self-containment working time was determined to be 7 days of repr oducible measurements.