Radiolabeling of a new nanovaccine candidate with [99mTc] TcO4Na and [67Ga] GaCl3 and studying the biodistribution with in vivo molecular imaging

Abstract

There is a need for novel vaccinations and nanoparticles (NPs) could be appropriate candidates as nanovaccines. In vivo molecular imaging could be used to accelerate the development of new nanovaccines. To obtain these images the nanovaccine must be radiolabeled. This study aimed to optimize the radiolabeling of a new Human Serum Albumin (HSA) NP bound to bevacizumab (NPA-B) and studied the biodistribution of NPA-B in mice after subcutaneous injection. The different parameters studied for optimization of radiolabeling were: influence of decreasing the end volume on size stability, influence of adding saline to NPA-B on size, stability of NPA-B at pH 4 and stability of NPA-B during 180 min. NPA-B were double radiolabeled (bevacizumab with [67Ga] GaCl3; HSA NP with [99mTc] TcO4Na) and subcutaneously administered to mice. SPECT/CT images showed activity in axillary and inguinal lymph nodes which indicates that immune cells transport NPA-B to the lymph node to initiate an immune response. In future studies bevacizumab will be replaced for S and N severe acute respiratory syndrome coronavirus (SARS-CoV-2) proteins to study the biodistribution of a novel COVID-19 vaccine.