Radiogallium-labeled gadolinium-porphyrin complex: A new agent for imaging and photodynamic therapy

 Metalloporphyrin-based contrast agents can improve probe functionality such as biocompatibility, prolonging presence in blood, and specific tumor accumulation. Herein, we report synthesis, structural characteristics, quality control, and nuclear imaging of new metalloporphyrin-based contrast agents.

 To combine photodynamic therapy (PDT), magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computerized tomography (SPECT), Gadolinium-proto porphyrin IX complex was synthesized via direct complexation method, then the metalloporphyrin (MP) was labeled with gallium-67 and gallium-68 in separated runs. In-vivo biodistribution studies were performed in mice bearing breast tumor (4T1 mouse mammary tumor cell line) and normal rats (for better visualization).

 Adsorption of the labeled compound into the tumor (ID/g % up to 4.6%), despite the small size of the tumor, had an upward trend at all times, and high and fast (less than 45 min) uptake of radiotracer in cancerous tumors was observed.  

  Fast and high tumor uptake revealed that this radiotracer could potentially be used as a theranostic agent.