Visible-light driven and efficient photoelectrochemical aptasensor constructed with N-doped carbon quantum dots-decorated TiO2 nanorods for determination of di-2-ethylhexyl phthalate

Here, a visible-light driven and efficient photoelectrochemical (PEC) aptasensor for highly sensitive and specific detection of di-2-ethylhexyl phthalate (DEHP) was constructed based on N-doped carbon quantum dotsdecorated TiO2 nanorods (N-CQDs-decorated TiO2 NRs) subtly integrated with biocatalytic precipitation (BCP). The N-CQDs-decorated TiO2 NRs synthesized through a facile hydrothermal method possess enhanced visible-light absorption capability and excellent PEC performance. The synthesized composites were used as the sensing material for developing a PEC aptasensor. Amino-functionalized complementary strand (cDNA) was first covalently immobilized on the N-CQDs-decorated TiO2 NRs, and then horseradish peroxidase (HRP)-labeled aptamer molecules were introduced onto the surface of composites by hybridization with cDNA. HRP-induced biocatalytic precipitation (BCP) caused the decrease of PEC detection signal, playing a role of signal amplification. The proposed PEC aptasensor shows good detection performance for DEHP with high sensitivity, selectivity, stability and reproducibility, and the detection limit is as low as 0.017 ng/L. Moreover, satisfying results were achieved for the DEHP assays in real environmental samples using the proposed PEC aptasensor. Thus, this present method would contribute a fresh idea to monitor DEHP or other pollutants in the environment.