Desenvolvimento de nanorradiofármaco à base de magnetita e processo de decoração com anticorpo monoclonal para determinação de alvo intracelular

Abstract

The advent of developing of radiopharmaceuticals at nanoscale, provides a new paradigm for Nuclear Medicine and emerges as a viable alternative to the treatment and diagnosis of tumors. The targeting and controlling release of these nanoradiopharmaceuticals ensures greater efficiency and decreases side effects and toxicity. Cutting-edge nanoparticles have specific recognition surface ligands, such as (monoclonal) antibodies, allowing increased recognition of tumor tissue. The nanoparticles of iron oxide (Fe3O4) as magnetite present high surface chemical reactivity, favoring the biomolecules binding as diffusion through tissues and lower toxicity. In this context, and interconnecting last generation technologies such as nuclear and nanotechnology, this work had the objective of producing, characterizing and studying the biodistribution of magnetic nanoparticles decorated with trastuzumab and labeled with technetium-99m radionuclide for the early and accurate detection of breast cancer. The magnetic nanoparticles were prepared by the thermodecomposition method and characterized by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), showing its spherical shape and its diameter of 7 nm. The conjugation of the monoclonal antibody to the surface of the magnetite nanoparticle was performed by means of a carbodiimide reaction. Labeling with technetium-99m was performed by the indirect method and its yield determined by Whatman 1 paper chromatography. The result showed a labeling yield greater than 97%. The SPECT image shows the uptake corresponding to the lesion, which has its location confirmed with the respective bioluminescence image. In the biodistribution study, healthy and induced human breast tumor xenograft-induced MCF-7 Balb/c micewere sacrificed two hours after the administration of the nanoradiopharmaceutical and dissected for counting the organs in the gamma counter. The xenoenxerted tumor had a large caption (> 10% of the total injected dose), corroborating the use of the nanoradiopharmaceutical. The biodistribution demonstrated that the nanoradiopharmaceutical has an excellent renal clearance, and little recognition by the macrophagic system as well as it was not able to permeate the blood-brain barrier, consubstantiating its safety of use. Finally, the nanoradiopharmaceutical showed high affinity to plasma proteins and low accumulation in the cardiac striatum, thus reducing its cardiotoxic effect. The data set establishes a profile of use as image agent for diagnostic purposes in breast cancer.