Synthesis, radiolabeling, biodistribution and fluorescent imaging of histidine-coupled hematoporphyrin

IntroductionHematoporphyrin (Hp) and hematoporphyrin derivatives (HpDs) have been widely used as photosensitizers in photodynamic therapy (PDT). Radiolabeling of HpDs is helpful for preclinical and clinical studies of PDT.MethodsThe histidine-coupled hematoporphyrin (His-Hp) was synthesized and radiolabeled with [99mTc(CO)3(H2O)3]+. Biodistribution of the radioligand and fluorescent imaging of His-Hp in mice bearing S180 tumor were investigated.Results[99mTc(CO)3]+-labeled His-Hp was electrically neutral, hydrophilic and stable. The biodistribution of the radioligand in S180 tumor-bearing mice was similar with that of nonlabeled HpD in the literature. The uptake of His-Hp in tumors and livers was confirmed by fluorescent imaging.ConclusionsThe complex [99mTc(CO)3]+–His-Hp might be suitable for in vivo dose evaluation of HpD in PDT.