A self-powered photoelectrochemical biosensor for H2O2, and xanthine oxidase activity based on enhanced chemiluminescence resonance energy transfer through slow light effect in inverse opal TiO2.

TiO2 inverse opal photonic crystals (IOPCs) were fabricated by using polystyrene template. TiO2 IOPCs based photoelectrochemical (PEC) biosensor was fabricated for the precise and stable detection of Heme without external irradiation. Then, the sensitization of TiO2 IOPCs was fulfilled with CdS quantum dots (QDs) by SILAR method to form ITO-TiO2 IOPCs-CdS:Mn electrode, which in turn was used to construct a PEC biosensor. The uniform porous structure of IOPCs with a large surface area is conducive to the excellent electronic transmission and QDs deposition. Also, the energy level matching between the conduction bands of CdS QDs and TiO2 IOPCs widened the range of light absorption, allowing for electron injection from excited CdS QDs to TiO2 upon luminol chemiluminescence, which enhanced the photocurrent. Furthermore, when the red edge of the photonic stop band of TiO2 IOPCs overlapped with the band gap of TiO2, and chemiluminescence emission of luminol, a substantial photocurrent increment was observed due in part to the slow light effect. The biosensor possesses a large linear detection range of 0.063-4 mM with a LOD of 19 μM for H2O2. Also, xanthine oxidase activity was determined with a linear measurement range of 0.01-15 mU/mL. Our strategy opens a new horizon to IOPCs based and QDs sensitized PEC sensing, which could be more sensitive, convenient and inexpensive for clinical and biological analysis. As far as we know, the largest photocurrent generation by luminol chemiluminescence was observed thanks to the use of semiconducting hybrid IOPCs material even at 0 V.