Recognition unit-free and self-cleaning photoelectrochemical sensing platform on TiO₂ nanotube photonic crystals for sensitive and selective detection of dopamine release from mouse brain

For implementing sensitive and selective detection of biological molecules, the biosensors are been designed more and more complicated. The exploration of detection platform in a simple way without loss their sensitivity and selectivity is always a big challenge. Herein, a prototype of recognition biomolecule unit-free photoelectrochemical (PEC) sensing platform with self-cleaning activity is proposed with TiO₂ nanotube photonic crystal (TiO₂ NTPCs) materials as photoelectrode, and dopamine (DA) molecule as both sensitizer and target analyte. The unique adsorption between DA and TiO₂ NTPCs induces the formation of charge transfer complex, which not only expends the optical absorption of TiO₂ into visible light region, thus significantly boosts the PEC performance under illumination of visible light, but also implements the selective detection of DA on TiO₂ photoelectrode. This simple but efficient PEC analysis platform presents a low detection limit of 0.15 nm for detection of DA, which allows to realize the sensitive and selective determination of DA release from the mouse brain for its practical application after coupled with a microdialysis probe. The DA functionalized TiO₂ NTPCs PEC sensing platform opens up a new PEC detection model, without using extra-biomolecule auxiliary, just with target molecule naturally adsorbed on the electrode for sensitive and selective detection, and paves a new avenue for biosensors design with minimalism idea.