Propylene carbonate-PVDF-HFP/MXene-based self-powered biosensor for auxiliary detection of salivary exosomal miRNA-155 in pediatric asthma.

This study developed a novel integrated self-powered biosensor for non-invasive auxiliary detection of pediatric asthma-associated miRNA-155. A flexible self-supporting electrode based on a propylene carbonate-PVDF-HFP/MXene composite was developed and implemented in an enzymatic biofuel cell self-powered sensing system. PVDF-HFP displayed excellent chemical stability and strong film-forming ability and MXene worked as electroactive materials in the self-supporting electrode substrate. The anode of the self-powered biosensor was prepared with Au NPs-decorated cobalt-nickel layered double hydroxide, which effectively enhanced electron transfer between enzymes and electrode to improve power output. Meanwhile, the cathode was designed based on [Ru(NH₃)₆]³⁺ as efficient electron acceptors. As a result, the glucose oxidation reaction at the anode and the reduction of [Ru(NH₃)₆]³⁺ at the cathode generated a measurable open-circuit voltage (E^OCV), which was real-time recorded through smartphone integration. The development of self-powered biosensor overcame the limitations of the low power output, functional layer detachment, and active site deactivation. The established integrated self-powered biosensing system successfully quantified salivary exosomal miRNA-155 across a broad concentration range (0.001-10,000 pM) with a detection limit of 0.21 fM. This work constructed a robust and portable platform suitable for non-invasive auxiliary detection of pediatric asthma, demonstrating promising applications in liquid biopsy.