Dual-Functional Nanobody Optical Probes for In Vivo Fluorescence Imaging and Photodynamic Therapy

Nanobodies have gained significant attention as promising tools for cancer diagnostics and treatment due to their unique ability to precisely target specific cancer cells. However, a major challenge lies in the site-specific incorporation of multifunctional molecules into nanobodies, as it is essential to link these molecules in a manner that preserves the nanobody's function and stability while retaining the desired therapeutic or diagnostic properties. This study outlines the development of dual-functional nanobody optical probes for enhanced cancer diagnostics and therapeutic interventions. We designed a dual-functional clickable linker that enables site-specific functionalization of the nanobody, facilitating the simultaneous conjugation of two dyes: indocyanine green for imaging and chlorin e6 for photodynamic therapy. In vitro cellular assays confirmed the successful labeling of the dual-functional dyes, with the nanobody probe exhibiting high cellular binding specificity. In vivo imaging of mice bearing Hep3B tumors revealed clear visualization with a high signal-to-noise ratio. Furthermore, PEGylated probes significantly improved tumor retention, enhancing both imaging contrast and photodynamic therapy efficacy as compared to free chlorin e6. These dual-functional nanobody probes show great promise for the precise diagnosis and treatment of malignant tumors.