Construction of a near-infrared light-assisted two-electrode self-powered photoelectrochemical aptasensor for sensitively aptasensing carbohydrate antigen and colorectal cancer CT26 cells

Abstract

A novel near-infrared (NIR) light-assisted two-electrode self-powered photoelectrochemical aptasensor (SP-PECA) was established for the selective and sensitive detection of carbohydrate antigen 50 (CA 50) and colon cancer CT26 cells. For this, the mesoporous carbon embedded with TiO2 nanocrystals and Au nanoparticles (represented by TiO2/mC@AuNPs) was prepared by calcining the polymer-Ti-based MOF (polyTi-MOF) incorporated with Au NPs at a high temperature (700 °C) under nitrogen atmosphere. The TiO2/mC@AuNP hybrid comprised plenty of oxygen vacancies and possessed enhanced NIR-light absorption ability, improved separation ability of photogenerated electrons and holes, and boosted electron transfer performance, showing an amplified photocurrent signal. The developed SP-PECA based on TiO2/mC@AuNP demonstrated an ultralow limit of detection (LOD) of 60 μU mL−1 within a range of 0.1 mU mL−1 to 100 U mL−1 of CA 50, together with other superior biosensing performances. The fabricated aptasensor also showed promising practicability for the detection of CA 50 from living CT 26 cells, giving a low LOD of 16 cells mL−1 within the range of 100 to 1 × 105 cells mL−1 and high selectivity against normal L929 cells. This work provides a new NIR-assisted SP-PEC-based aptasensing strategy for the rapid and sensitive detection of cancer markers in living cancer cells.