Highly Selective and Sensitive microRNA-210 Assay Based on Dual-Signaling Electrochemical and Photocurrent-Polarity-Switching Strategies

Highly sensitive and selective microRNA (miRNA) assay is of great significance for disease diagnosis and therapy. Herein, a magnetic-assisted electrochemistry (EC)–photoelectrochemistry (PEC) dual-mode biosensing platform was developed for miRNA-210 detection based on dual-signaling EC and photocurrent-polarity-switching PEC strategies. Porous magnetic Fe₃O₄ octahedra with a large surface area were synthesized by calcining Fe-based metal–organic frameworks. Subsequently, the magnetic photoelectric materials (Fe₃O₄@CdS) were developed by the successive ionic layer adsorption and reaction method in Cd²⁺ and S^2– solutions. Then, the self-assembled DNA nanoprisms contained three thiols/hanging arms that could capture miRNA-210 efficiently and were anchored to the Fe₃O₄@CdS octahedra via the Cd–S bond. When miRNA-210 was present, the double-stranded DNA concatemers [the self-assembled duplex helixes based on a pair of methylene blue (MB)-labeled single-stranded DNAs (AP1 and AP2) through the hybridization chain reaction and then intercalated with adriamycin (Dox) into their grooves] were connected with the Fe₃O₄@CdS-DNA nanoprisms. MB and Dox not only acted as the electrochemical probes but also synergistically switched the photocurrent polarity of the Fe₃O₄@CdS octahedra. Thus, miRNA-210 was assayed sensitively and selectively via the proposed EC–PEC dual-mode biosensing platform. Additionally, the abovementioned recognition steps occurred in a homogeneous system, and the effects of the impurities and interferences on the miRNA-210 assay could be easily avoided by magnetic separation due to the good magnetic properties of Fe₃O₄ octahedra. The proposed EC–PEC dual-mode biosensing platform showed a wide range of potential applications in bioanalysis and early diagnosis of disease.