Polydopamine coated multifunctional lanthanide theranostic agent for vascular malformation and tumor vessel imaging beyond 1500 nm and imaging-guided photothermal therapy

The optical imaging guided tumor vessels and vascular malformation visualization by using the second near infrared emission beyond 1500 nm (NIR-II) is emerged as the next generation fluorescence imaging technique for early tumor diagnosis and identification of tumor-associated vascular features. On the other hand, developing theranostic probes for NIR-II imaging guided photothermal therapy (PTT) is of great significance, which is rarely explored. Herein, a high performance theranostic nanoplatform based on the core-shell structured NaLuF4 nanorods@polydopamine (denoted as NRs@PDA) by integrating the new advanced NIR-II imaging beyond 1500 nm with PTT function was developed for tumor-associated vascular malformation visualization and imaging-guided PTT. Methods: In this work, the hydrophilic NaLuF4 NRs@PDA therapeutic probe was synthesized by using a reverse microemulsion method. The crystal phase, morphology, emission spectra and photothermal performance of the synthesized samples were systematically characterized. The NIR-II optical imaging and photothermal properties were investigated by in vitro and in vivo experiments. Results: The NaLuF4 NRs@PDA therapeutic probe possessed efficient NIR-II emission centered at 1525 nm with high quantum yield (QY), good photo-stability and high biocompatibility. In vivo NIR-Ilb imaging based on the designed probe can clearly visualize the whole-body vessel and brain vessel with high spatial resolution, especially tumor-associated vessels. In addition, in vitro and in vivo experiments also demonstrated that the designed NaLuF4 NRs@PDA probe possessed efficient photothermal conversion efficiency (40.18%) for PTT ablation of tumor. Conclusion: With the excellent NIR-II imaging ability and PTT of tumor, the designed theranostic nanoplatform successfully realize the simultaneous tumor vessel diagnosis and tumor therapy, which may provide the opportunity of designing new theranostic bioprobes with combination of the NIR-II optical imaging technique and PTT function for tumor diagnosis and therapy.