A self-powered biosensor with cascade amplification capability facilitates ultra-sensitive detection of microRNA biomarkers

Sensitive microRNA (miRNA) detection is crucial for cancer diagnosis. Self-powered biosensors that are used for miRNA detection show the advantages of no external power supply, mild reaction conditions, portability, etc., but still face the challenges of low efficiency of solid electrode adsorption enzyme and insufficient enzyme active site. Here, the MnS@MoS2 composite electrode substrate boosts enzyme load, accelerates electron transfer, and enhances detection. Catalytic hairpin self-assembly (CHA) and Hybridization chain reaction (HCR) cascade biosignal amplification enables current signal amplification via molecular recognition. When miRNA-199a is present, CHA and HCR trigger signal cascade amplification, achieving high sensitivity and specificity while powering the system. The sensor has a 0.5 fmol/L - 100 pmol/L linear response and a 0.14 fmol/L limit of detection (LOD). Additionally, the test signal is transmitted to a smartphone interface via Bluetooth, enabling portable, enabling portable, real-time detection. Our work shows this self-powered biosensor offers a new path for ultrasensitive miRNA detection, aids rapid disease biomarker monitoring, and broadens self-powered sensor use in medical diagnosis.