Antifungal activity of amphotericin B conjugated to nanosized magnetite in the treatment of paracoccidioidomycosis

This study reports on in vitro and in vivo tests that sought to assess the antifungal activity of a newly developed magnetic carrier system comprising amphotericin B loaded onto the surface of pre-coated (with a double-layer of lauric acid) magnetite nanoparticles. The in vitro tests compared two drugs; i.e., this newly developed form and free amphotericin B. We found that this nanocomplex exhibited antifungal activity without cytotoxicity to human urinary cells and with low cytotoxicity to peritoneal macrophages. We also evaluated the efficacy of the nanocomplex in experimental paracoccidioidomycosis. BALB/c mice were intratracheally infected with Paracoccidioides brasiliensis and treated with the compound for 30 or 60 days beginning the day after infection. The newly developed amphotericin B coupled with magnetic nanoparticles was effective against experimental paracoccidioidomycosis, and it did not induce clinical, biochemical or histopathological alterations. The nanocomplex also did not induce genotoxic effects in bone marrow cells. Therefore, it is reasonable to believe that amphotericin B coupled to magnetic nanoparticles and stabilized with bilayer lauric acid is a promising nanotool for the treatment of the experimental paracoccidioidomycosis because it exhibited antifungal activity that was similar to that of free amphotericin B, did not induce adverse effects in therapeutic doses and allowed for a reduction in the number of applications

Selective Conjugation of Proteins by Mining Active Proteomes through Click-Functionalized Magnetic Nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) coated with azide groups were functionalized at the surface with biotin (biotin@SPIONs) and cysteine protease inhibitor E-64 (E-64@SPION5) with the purpose of developing nanoparticle-based assays for identifying cysteine proteases in proteomes. Magnetite particles (ca. 6 nm) were synthesized by microwave-assisted thermal decomposition of iron acetylacetonate and subsequently functionalized following a click chemistry protocol to obtain biotin and E-64 labeled particulate systems. Successful surface modification and covalent attachment of functional groups and molecules were confirmed by FT-IR spectroscopy and thermal gravimetric analysis. The ability of the surface-grafted biotin terminal groups to specifically interact with streptavidin (either horseradish peroxidase [(HRP)-luminol-H2O2] or rhodamine) was confirmed by chemiluminescent assay. A quantitative assessment showed a capture limit of 0.55-1.65 mu g protein/100 mu g particles. Furthermore, E-64@SPION5 were successfully used to specifically label papain-like cysteine proteases from crude plant extracts. Owing to the simplicity and versatility of the technique, together with the superparamagnetic behavior of FeOx-nanoparticles, the results demonstrate that click chemistry on surface anchored azide group is a viable approach toward bioconjugations that can be extended to other nanoparticles surfaces with different functional groups to target specific therapeutic and diagnostic applications