Free carrier-enhanced Bi/Bi₂S₃ nanoparticles enable precise OCT catheter-guided interventional photothermal therapy...

Current clinical colorectal cancer treatments usually possess unsatisfactory effects, mainly because of unavoidable surgical trauma and multidrug resistance. Precise and minimally invasive theragnostic technology has advanced through miniaturized catheter intervention with imaging-guided treatment methods; however, previously reported approaches cannot simultaneously perform in situ real-time imaging and therapy. We proposed a strategy of 0.9 mm catheter-based optical coherence tomography imaging-guided interventional photothermal therapy at 1310 nm for orthotopic colorectal cancer. Specifically, folate-modified Bi/Bi₂S₃ nanoparticles showed intense scattering signals and local hyperpyrexia under 1310 nm laser irradiation in vitro and in vivo due to the localized surface plasmon resonance effect, enabling imaging-guided precise tumor treatment. Histopathological and blood biochemistry analyses confirmed the high biosafety and negligible long-term toxicity of Bi/Bi₂S₃ nanoparticles. This new method offers a feasible methodology for catheter-based precise interventional photon theragnostics. STATEMENT OF SIGNIFICANCE: Emerging minimally invasive techniques have been explored for the treatment of colorectal cancer (CRC); however, these reported approaches cannot reach the requirement of precise orthotopic cancer treatment due to the lack of in situ real-time imaging guidance. This study proposes a 0.9 mm catheter-based OCT imaging-guided interventional photothermal therapy (IPTT) strategy at 1310 nm for treating orthotopic CRC. Folate-modified plasmonic Bi/Bi₂S₃ nanoparticles enable real-time imaging-guided IPTT by providing strong scattering signals and local hyperthermia. This approach allows simultaneous transmission of imaging and therapy light in the same optical fiber, offering a promising method for precise CRC theragnostics and addressing the gap of in situ real-time imaging during IPTT.