Magnetite-based nanobioplatform for site delivering Croton cajucara Benth essential oil

Abstract

Surface coating magnetic nanoparticles can be realized using organic moieties, such as essential oil (EO) extracted from Croton cajucara Benth leaves, a common plant from the Brazilian Amazon region successfully used for infusion in popular medicine. Although, there are reports in the literature indicating the protective and healing actions of the EO on gastric lesions, the inclusion of the magnetic core to control (targeting and retaining) the MNPs in specific sites can improve the performance of the EO molecules for the treatment of gastric disorders. Therefore, in this work, we report on fabrication and characterization of surface-coated magnetite nanoparticles (MNPs), aiming thermal-assisted site delivering EO. Firstly, oleic acid (OA) coated MNPs (sample M1) were fabricated using a thermal decomposition route. Secondly, the OA-coated MNPs were dressed with EO (sample M2). Meanwhile, x-ray diffraction and transmission electron microscopy data confirmed formation of spherically-shaped magnetite core while successful single OA coating and double OA + EO coating of MNPs was confirmed by infrared spectroscopy and thermogravimetric analysis (TGA). TGA results indicated release of the EO at ∼50 °C, whereas the OA is released only above ∼380 °C. Blocking (TB) and irreversible (TIRR) temperatures of samples M1 (TB = 210 K; TIRR = 210 K) and M2 (TB = 35 K; TIRR = 215 K) were assessed from magnetic measurements data analysis. In sample M2, the difference TB-TIRR (180 K) was related to inhomogeneous partial shifting of OA molecules by EO molecules whereas the remarkable reduction of MS with respect to sample M1 was assigned to a dead surface layer dominated by ferrous ions in low-spin state. Moreover, the lower TB value we have found in sample M2 (∼35 K) indicates negligible particle-particle interactions due to the successful double coating (OA plus EO) of the MNPs, in contrast to that obtained in sample M1. In sample M2 weakening of particle-particle interaction warrants superparamagnetic properties which can be used to obtain magnetic resonance image and for guiding the MNPs to targeting sites using gradients of external magnetic field. Therefore, the combination of the improved magnetic properties plus the detachment of EO at ∼50 °C (while keeping stable the OA coating) via magnetohyperthermia makes the double coated system (sample M2) a very promising candidate for site delivering of EO to treat gastrointestinal disorders.