Nanoheterojunction‐Based Self‐Powered Biosensor Integrated with Smartphones for Early Cancer Detection

ABSTRACT Early diagnosis of cancer is critical for improving patient survival rates. As biomarkers closely associated with tumorigenesis, microRNAs (miRNAs) remain challenging to detect with sufficient sensitivity, simplicity, and portability. This study presents a self‐powered, dual‐readout electrothermal biosensing chip that integrates an enzyme‐free catalytic hairpin assembly (CHA) amplification strategy with hierarchical SnO 2 @MoS 2 hollow spheres for highly sensitive and specific detection of microRNA‐126 (miRNA‐126). The target miRNA concentration is directly quantified via electrochemical signals, while a thermal transduction mechanism converts electrochemically generated intermediates into the photothermal agent Oxidized 3,3’,5,5’‐tetramethylbenzidine (oxTMB). Both electrochemical and thermal signals are visualized in real time through a smartphone interface, enhancing detection reliability and interpretability. Compared with conventional single‐mode electrochemical methods, this platform reduces cost and operational complexity through enzyme‐free amplification, while dual‐signal cross‐validation improves accuracy. The energy‐autonomous design eliminates the need for an external power supply, enabling portable, on‐site rapid testing. Experimental results demonstrate a picomolar detection limit for miRNA‐126 and excellent performance in serum samples. Overall, this study provides a promising strategy for sensitive and specific early cancer screening and point‐of‐care diagnostics.