Synthesis and evaluation of magnetite-based nanobioconjugates for drug delivery in melanoma treatment

Abstract

Cancer is defined as the abnormal growth of cells and is one of the leading causes of death and morbidity worldwide. Among the most aggressive types of cancer, melanoma accounts for 80% of skin cancer-related deaths. When diagnosed early, melanoma can be surgically removed with good prognosis. Once it becomes metastatic, conventional treatment options as chemotherapy must be combined with surgery. However, this alternative has limitations as they impair quality of life of patients due to their multiple side effects. Therefore, magnetite nanobioconjugates as nanocarriers for drug delivery are proposed to overcome lack of specificity, cytotoxicity and increase the effect of permeability and retention of the drugs at the tumor site. Magnetite nanoparticles (MNPs) were synthesized by the chemical co-precipitation method and then, different anticancer drugs were conjugated on its surface through three types of immobilizations: direct immobilization, immobilization on PEG-coated MNPs and co-immobilization of the drugs and a membrane-translocating agent, all this, in nanoparticles with and without functional linker for drug release. The obtained nanobioconjugates were characterized by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) to assure the correct synthesis and immobilization of the molecules. Then, the morphology and size were verified via Dynamic light scattering (DLS) and transmission electron microscopy (TEM) images, and their biocompatibility was tested through lactate dehydrogenase (LDH), hemolysis and platelet aggregation assays. Finally, the cellular internalization and endosomal escape pathways were investigated via confocal microscopy. The nanobioconjugates were correctly synthetized with uniform size and shape, and the Temozolomide (TMZ) and Paclitaxel (PX) presented percentages of conjugation efficiency in the MNPs surfaces between 1%-7% and 1%-3.6%, respectively. Moreover, remarkable biocompatibility of the nanobioconjugates was attained in terms of hemocompatibility (hemolysis below 1%) and platelet aggregation (like the negative control or less than 10% with respect to PBS 1X). The nanobioconjugates showed high cytotoxicity in HaCaT and A-375 cells after 72 h of exposure in comparison with the free drugs, and the vehicles that showed the best cytotoxic performance in melanoma cells for each drug were selected. The nanobioconjugates were internalized into cells through caveolins, clathrins, and macropinocytosis via endocytosis. The results confirm the successful synthesis of the nanobioconjugates and their potential as a drug delivery system, given the reduction of cytotoxicity in healthy cells while increasing retention in tumors.