A competitive photoelectrochemical aptasensor for thrombin detection based on the use of TiO2 electrode and glucose oxidase label

Abstract A novel competitive photoelectrochemical aptasensor for thrombin (TB) detection is proposed using TiO 2 electrode coupled with TB-Au nanoparticles (AuNPs)–glucose oxidase (GOx) labels. To construct the aptasensor, chitosan was coated on the TiO 2 surface for the further immobilization of TB aptamer that was bridged by the use of glutaraldehyde. TB detection was then performed based upon the competitive interaction of TB and TB-AuNPs-GOx bioconjugate with TB aptamer on the electrode. GOx could catalyze the glucose to produce H 2 O 2 , which acts as an effective electron donor to deplete the photogenerated holes located at the valence band of excited TiO 2 , resulting in the enhanced photocurrent response. Under the optimal conditions, the as-prepared PEC aptasensor exhibits excellent analytical property for detection of TB in the range from 1.0 × 10 − 12  mol L − 1 to 1.0 × 10 − 8  mol L − 1 with a detection limit of 1.9 × 10 − 13  mol L − 1 . Moreover, the aptasensor was also successfully applied for the determination of TB in human plasma. The present strategy provides a promising method for the future development of PEC aptasensor for advanced biochemical analysis.