Visible-light-driven photoelectrochemical aptasensor based on reduced graphene oxide/Ti-Fe-O nanotube arrays for highly sensitive and selective determination of microcystin-LR

摘要

Microcystin-LR (MC-LR) is one of the highly concerned microcystins with strong hepatotoxicity. In this work, a visible-light-driven photoelectrochemical (PEC) aptasensor has been successfully developed for MC-LR based on reduced graphene oxide (rGO)/Ti-Fe-O nanotubes (NTs). Vertically-aligned Ti-Fe-O NTs are in situ prepared on Ti-Fe alloy by electrochemical anodic oxidation to provide an outstanding photoanode substrate with good visible light response ability. RGO is further electrochemically deposited onto Ti-Fe-O NTs, acting not only as the molecular bridge for immobilization of MC-LR aptamers (Apt), but also as the PEC signal amplification element. Attributed to the large pi-conjugated structure of rGO which can effectively promote photo-generated electron-hole separation, as well as the good visiblelight activities of Ti-Fe-O NTs, the constructed Apt/rGO/Ti-Fe-O NTs sensor exhibits prominent determination performance for MC-LR with a detection limitation of 5 fM. High selectivity and stability towards MC-LR is further proven to the aptasensor by performing the co-existing experiments and long-termed replicates. Meanwhile, satisfactory results are obtained when applying in real water sample investigation. A promising visible-light-driven PEC platform for highly sensitive and selective detection of MC-LR has thus been provided. (C) 2019 Elsevier Ltd. All rights reserved.