Fiber-Optic Quantum Dots Sensor for Dynamic and Quantitative Thermal Monitoring of Spheroids toward Single-Cellular Resolution.

Accurate monitoring of thermal dynamics at the single-cellular scale is crucial for elucidating metabolism, signaling pathways and disease mechanisms, yet remains hampered by the limited stability and spatiotemporal resolution of current sensors. Here, we report a fiber-optic quantum dots sensor (FOQDS), which is based on a tapered fiber optic tip functionalized with CdSe/CdS/ZnS QDs and encapsulated by a dense Al2O3 layer to ensure exceptional long-term stability. FOQDS features a linear thermal response with high sensitivity (145 pm/°C), a temporal resolution of <10 μs, with the potential to achieve single-cellular-scale spatial precision. This performance enables quantitative and real-time monitoring of pharmacologically induced thermal fluctuations within living three-dimensional glioblastoma spheroids. This work provides a stable and minimally invasive platform for monitoring cellular thermogenesis in physiologically relevant microenvironments, with promising prospects in applications of fundamental biology and precision therapeutics.