A Novel Non-Invasive Sweat Lactate Biosensor and Its Application in Human Exercise Monitoring

Haolin Xin¹Zilin Wei¹Yingkai Qin¹Aili Wei¹Kang Chen²Longfei Xu¹Bin Li³Kun Wang^1*Tianhui Wang¹

• ¹Military Medical Sciences Academy, Tianjin 300050, China, Tianjin, China
• ²Tianjin University of Sport, Tianjin, China
• ³No. 950 Hospital of the Chinese People’s Liberation Army, Yecheng 844999, China, Yecheng, China

Lactate monitoring is critical for clinical diagnostics and athletic performance optimization. Traditional methods rely on invasive blood sampling, whereas sweat offers a promising non-invasive alternative. This study presents a highly sensitive fluorescence resonance energy transfer (FRET)-based aptasensor for lactate detection in sweat. The platform employs aptamer-functionalized core-shell upconversion nanoparticles (APT-CS-UCNPs) as energy donors and Fe3O4-decorated molybdenum disulfide (MoS2) nanosheets as quenchers. In the absence of lactate, close proximity (<10 nm) between APT-CS-UCNPs and MoS2 enables efficient FRET, quenching fluorescence at 545 nm. Lactate binding induces aptamer conformational changes, increasing the donor-acceptor distance and restoring fluorescence. The biosensor demonstrates a wide linear detection range (0-30 mM, R2=0.9981) and an ultralow detection limit (0.07785 mM), surpassing most electrochemical sensors. Validation in spiked sweat samples yielded recovery rates of 98.45-104.28%, with minimal cross-reactivity to common interferents. Comparative analysis with commercial kits and prior methods confirmed superior sensitivity and operational simplicity. Successful lactate quantification in real human sweat samples underscores its clinical practicality. This FRET-based aptasensor establishes a robust, non-invasive platform for rapid metabolite monitoring using standard laboratory instrumentation, with significant potential for clinical and athletic applications.