^99m Tc-anti-epidermal growth factor receptor nanobody for tumor imaging

Nanobodies are important biomolecules for tumor targeting. In this study, we synthesized and labeled anti-epidermal growth factor receptor (EGFR) nanobody OA-cb6 with ^99m Tc(CO)₃⁺ and evaluated its characteristics for targeting the EGFR in the A431 human epidermal carcinoma cell line. Nanobody radiolabeling was achieved with high yield and radiochemical purity, and the radioconjugate was stable. Biodistribution results in nude mice exhibited a favorable tumor-to-muscle ratio at 4-hr postinjection, and tumor location was visualized at 4 hr after injection of radiolabeled nanobody. Our result showed that the OA-cb6-^99m Tc-tricarbonyl radiolabeled nanobody is a promising radiolabeled biomolecule for tumor imaging in cancers with high EGFR overexpression.