Visible light driven photoelectrochemical thrombin aptasensor based on uniform TiO2 nanotube arrays modified with CuOx and perylene-3,4,9,10-tetracarboxylic acid

Abstract

In this work, a sensitive signal-off photoelectrochemical (PEC) thrombin aptasensor with satisfying specificity is proposed, in which the evident initial photocurrent response is produced by the photoanode and the signal amplification strategy toward the target is based on the specific bio-affinity properties between thrombin and their aptamers. The photoanode was fabricated with uniform TiO2 nanotube arrays decorated with CuOx and perylene-3,4,9,10-tetracarboxylic acid (PTCA). After the decoration of CuOx and PTCA, both possessing a strong absorption in visible region, the photocurrent response is improved greatly. Pt nanoparticles were modified on the photoanode electrode to immobilize thrombin aptamers, which could obviously improve the conductivity of the photoanode electrode owing to the excellent conductivity of Pt nanoparticles. The non-conductive complex leads to dramatical decrease in the photocurrent value due to the steric hinder effect. Based on the joint action of evident photocurrent response of photoanode and significant signal amplification strategy, the aptasensor in this project offers a wide linear range from 0.0003 nM to 10 nM, with a detection limit (3S/N) of thrombin down to 55 fM. Moreover, the as-fabricated aptasensor exhibits acceptable selectivity and stability, providing a meaningful attempt for the detection of thrombin.