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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 TiO 2 nanotube photonic crystal (TiO 2 NTPCs) materials as photoelectrode, and dopamine (DA) molecule as both sensitizer and target analyte. The unique adsorption between DA and TiO 2 NTPCs induces the formation of charge transfer complex, which not only expends the optical absorption of TiO 2 into visible light region, thus significantly boosts the PEC performance under illumination of visible light, but also implements the selective detection of DA on TiO 2 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 TiO 2 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. [ABSTRACT FROM AUTHOR]

In this work, the typical honeycomb-nanoparticle heterostructure with honeycomb TiO 2 nanotube arrays (HTNTs) as light harvesting unit and Bi 2 MoO 6 nanoparticles (BMO) as recognition unit was prepared for highly sensitive and selective nano-enzymatic photoelectrochemical L-cysteine biosensor. [Display omitted] • The typical honeycomb-nanoparticle heterostructure between HTNTs and BMO improves the light harvesting behavior and the separation efficiency of the electron-hole pairs. • BMO nanoparticles fully dispersed on HTNTs with large specific surface area provides more sites for Cyst recognition. • Cyst can be specifically recognized through the Bi-S bonds. • The PEC enzyme-free biosensor shows good performance for Cyst with low detection limit and wide linear range. Improving light harvesting behavior and recognition sites of sensor is an effective way to achieve highly sensitive and selective detection of nano-enzymatic photoelectrochemical (PEC) L-cysteine (Cyst). In this work, the Bi 2 MoO 6 -TiO 2 composite (BMO-HTNTs) with honeycomb TiO 2 nanotube arrays (HTNTs) as light harvesting unit and Bi 2 MoO 6 nanoparticles (BMO) as recognition unit was prepared. The typical honeycomb-nanoparticle heterostructure between HTNTs and BMO improves the separation efficiency of the electron-hole pairs. Moreover, BMO nanoparticles fully dispersed on HTNTs with large specific surface area provide more sites for Cyst recognition. The composite exhibited the enhanced light absorption and higher photocurrent density at 0.2 V (vs. Ag/AgCl), which was 4 times than that of HTNTs under simulated light. Ingeniously, Cyst can not only be specifically recognized through the Bi-S bonds but also act as electron donor to scavenge the photogenerated holes of BMO-HTNTs, resulting in the increase of PEC responses. The PEC sensor showed superior analytical performance for Cyst detection with two linear regression equations in the range of 500 nM to 500 μM and a detection limit of 150 nM. The results of the enzyme-free sensor on practical urine and serum samples demonstrated its promising application in biological monitoring. [ABSTRACT FROM AUTHOR]