Fluorescent, Plasmonic, and Radiotherapeutic Properties of the (177)Lu–Dendrimer-AuNP–Folate–Bombesin Nanoprobe Located Inside Cancer Cells

The integration of fluorescence and plasmonic properties into one molecule is of importance in developing multifunctional imaging and therapy nanoprobes. The aim of this research was to evaluate the fluorescent properties and the plasmonic–photothermal, therapeutic, and radiotherapeutic potential of (177)Lu–dendrimer conjugated to folate and bombesin with gold nanoparticles in the dendritic cavity ((177)Lu–DenAuNP–folate–bombesin) when it is internalized in T47D breast cancer cells. The intense near-Infrared (NIR) fluorescence emitted at 825 nm from the conjugate inside cells corroborated the usefulness of DenAuNP–folate–bombesin for optical imaging. After laser irradiation, the presence of the nanosystem in cells caused a significant increase in the temperature of the medium (46.8°C, compared to 39.1°C without DenAuNP–folate–bombesin, P < 0.05), resulting in a significant decrease in cell viability (down to 16.51% ± 1.52%) due to the (177)Lu–DenAuNP–folate–bombesin plasmonic properties. After treatment with (177)Lu–DenAuNP–folate–bombesin, the T47D cell viability decreased 90% because of the radiation-absorbed dose (63.16 ± 4.20 Gy) delivered inside the cells. The (177)Lu–DenAuNP–folate–bombesin nanoprobe internalized in cancer cells exhibited properties suitable for optical imaging, plasmonic–photothermal therapy, and targeted radiotherapy.