NIR II Imaging-Guided Self-Illuminating Fiber-Optic Theranostics

Fiber-optic technology addresses nanoparticle-induced systemic toxicity and limited light penetration in phototheranostics. However, navigating optical fibers in vivo through current medical imaging modalities exhibits critical limitations, leaving "last-mile" interventional challenges unresolved. Herein, we demonstrate a near-infrared II imaging-guided self-illuminating fiber-optic theranostic probe strategy, integrating portable near-infrared II self-illumination-based navigation, luminescent ratiometry-mediated tumor identification, and multimodal thermal dose monitoring under photothermal therapy. It encapsulates erbium ions within the fiber to generate visible upconversion luminescence through 980 nm near-infrared II excitation. Recycling residual excitation light as a beacon for near-infrared II/visible ratiometry imaging renders a "waste-to-resource" paradigm and can be visualized using a commercial smartphone. Leveraging this strategy, we achieve a 100% cure rate in murine xenograft models with a 33% reduction in fiber probes required. This platform provides a robust framework for minimally invasive cancer theranostics, delivering deep tissue penetration (>10 mm) with a compact form factor (probe diameter <200 μm) to advance clinically translatable image-guided precision oncology.