A photoelectrochemical aptasensor for mucin 1 based on DNA/aptamer linking of quantum dots and TiO2 nanotube arrays

Abstract

Herein, a novel strategy for the construction of a photoelectrochemical aptasensor for tumor marker mucin 1 (MUC1) was presented, which was based on the effective photoelectron transfer from CdTe quantum dots (QDs) to TiO₂ nanotube arrays (TiO₂ NTs) through DNA chains. First, we prepared a series of TiO₂ NTs on titanium foil by the electrochemical anodization technique, and electrodeposited Au nanoparticles to improve their electrical conductivity and biocompatibility, which could load a high amount of MUC1 aptamers by Au–S bonds. Then, the synthesized c-DNA@QDs were immobilized on the TiO₂ NTs by hybridization of c-DNA and aptamers to form a TiO₂ NT/aptamer/c-DNA@QD aptasensor. Detailed studies indicated that, under the irradiation of visible light, the aptasensor had a good photocurrent response due to the excellent photosensitivity of CdTe QDs and electrical conductivity of DNA chains and Au/TiO₂ NTs. More importantly, the photocurrent response of the aptasensor was significantly affected by the TiO₂ NT morphology and DNA chain length, which could be regulated by changing the tube length of TiO₂ NTs and the chain length of DNA linking QDs and TiO₂ NTs. Furthermore, the TiO₂ NT/aptamer/c-DNA@QD aptasensor for MUC1 exhibited good reproducibility and stability, a wide linear range of 0.002–0.2 μM, and high sensitivity with a LOD of 0.52 nM, which could be applied to the determination of MUC1 in human serum samples with good accuracy and recoveries. Therefore, the developed aptasensor could offer a promising feature for the analytical application in complex biological samples.