Study of the tissue distribution of potential boron neutron-capture therapy agents based on conjugates of chlorin e 6 aminoamide derivatives with boron nanoparticles

Abstract

Boron neutron-capture therapy of cancer is based on the ability of the 10B isotope to capture thermal neutrons; it is one of the most promising techniques in radiation therapy. The high content and selective accumulation of 10B in the tumor tissue are the most important prerequisites for its efficacy. The purpose of this study was to determine the biodistribution of cobalt bis(dicarbollide) conjugates with chlorin e6 amino amide derivatives. Experiments were carried out in Balb/c mice with transplanted CT-26 murine colon carcinoma. Boron-containing conjugates were injected into the tail vein at a dose of 10 mg/kg. The conjugate accumulation in tumor tissue and organs was studied by laser scanning microscopy. Excitation was performed at the wavelength of 514 nm; the signals were recorded in the range of 560–710 nm in increments of 10 nm. To evaluate the amount of the boron conjugate, we calculated the intensity of the fluorescence signal of the samples under investigation. At 3 h after administration of the agent, a high level of fluorescence was observed in the liver, spleen, and lung. The tumor/muscle accumulation ratio was approximately 3. The study demonstrated that boron derivatives of chlorin e6 are promising agents for boron neutron-capture therapy.