Quantum Photothermal Self-Monitoring Fiber Probes for In Vivo Photothermal Therapy.

The photothermal properties of diamond nitrogen-vacancy (NV) centers enable simultaneous fluorescence emission and localized heating, yet conventional free-space quantum systems suffer from limited photothermal efficiency (typically<4°C/mW) and inadequate microwave integration (large in size). We developed a miniaturized quantum photothermal fiber probe utilizing a novel metal/polymer/glass composite optoelectronic fiber that simultaneously guides both lightwave and microwave radiation (at GHz). By integrating a micron-scale diamond at the fiber tip, the probe achieves enhanced photothermal conversion (13°C/mW, 25°C-120°C range) while providing real-time self-monitoring through temperature-dependent zero-field splitting measurements with 0.2°C thermal resolution at the micrometer scale. This mass-producible platform represents a new class of biocompatible quantum sensors combining high thermal efficiency and precise temperature feedback, as demonstrated by successful promotion of in vivo spinal cord injury repair through controlled thermal stimulation.