Visible Light-Driven Self-Powered Device Based on a Straddling Nano-Heterojunction and Bio-Application for the Quantitation of Exosomal RNA

This paper reports the design and fabrication of a self-powered biosensing device based on TiO2 nanosilks (NSs)@MoS2 quantum dots (QDs) and demonstrates a bioapplication for the quantitative detection of exosomal RNA (Homo sapiens HOXA distal transcript antisense RNA, HOTTIP). This self-powered device features enhanced power output compared to TiO2 NSs alone. This is attributed to the formation of a heterojunction structure with suitable band offset derived from the hybridization between TiO2 NSs and MoS2 QDs, i.e., the straddling (Type I) band alignment. The sensitization effect and excellent visible light absorption provided by MoS2 QDs can prolong interfacial carrier lifetime and improve energy conversion efficiency. This self-powered biosensing device has been successfully applied in quantitative HOTTIP detection through effective hybridization between a capture probe and HOTTIP. The successful capture of HOTTIP leads to a sequential decrease in power output, which is utilized for ultrasensitive quantitative HOTTIP detection, with a linear relationship of power output change versus the logarithm of HOTTIP concentration ranging from 5 fg/mL to 50 000 ng/mL and a detection limit as low as 5 fg/mL. This TiO2 NSs@MoS2 QDs-based nanomaterial has excellent potential for a superior self-powered device characterized by economical and portable self-powered biosensing. Moreover, this self-powered, visible-light-driven device shows promising applications for cancer biomarker quantitative detection.