Tc-labeled porphyrin–lipid nanovesicles

Porphyrin–lipid nanovesicles (PLN) have been developed with intrinsic capabilities as activatable multimodal photonic contrast agents. Radiolabeling of PLN encapsulating drugs could eventually be able to provide quantitative in vivo information for diagnosing and treating diseases. In this study, we developed Tc-labeled porphyrin–lipid nanovesicles (Tc-PLN) as a cargo-encapsulated formulation without significant impact on liposome integrity and encapsulation stability. 50mM calcein was encapsulated into PLN by probe sonication. The size of the PLN was about 150 nm. The PLN were then reacted with Tc using SnCl2 dissolved in 1mM HCl as a reducing agent and incubated for 10min at 22 C. The radiolabeling efficiency and stability of Tc-PLN were evaluated by instant thin-layer chromatography and lowpressure liquid chromatography (LPLC). Tc labeling was successful with a492% labeling efficiency. LPLC showed that the liposomal elution peaks of the porphyrin–lipid and the calcein overlapped with the radioactivity elution peak of Tc-labeled PLN. The Tc-labeling procedure did not change the size of PLN. Encapsulated calcein remained inert inside PLN. Thus, this work lays out a simple and effective radiolabeling method using SnCl2 in HCl in the preparation of Tc-PLN.