Chitosan-coated dapsone-loaded lipid-core nanocapsules: Growth inhibition of clinical isolates, multidrug-resistant Staphylococcus aureus and Aspergillus ssp.

Lecithin-polysorbate 80-lipid-core nanocapsules (LNC) or chitosan-coated LNC (LNC-CS) containing or not dapsone (DAP) were prepared and characterized. Particle size varied from 126 to 130 nm (laser diffraction) and from 114 to 125 nm (z-average diameter by dynamic light scattering). The pH values ranged from 4.15 to 4.57 and zeta potential inverted from -15 (LNC) to +23 mV (LNC-CS) and from -13 (DAP-LNC) to +21 mV (DAP-LNC-CS). Transmission electron microscopy analysis evidenced four layers of micellar structures coating LNC, constituting a hydrophilic corona. For the first time, a sequence of spherical to cylindrical micellar transformation was observed at the nanocapsule corona. Biological assays demonstrated that DAP-LNC, LNC-CS and DAP-LNC-CS act as growth inhibitors of five clinical isolates of Staphylococcus aureus, which exhibited multidrug-resistance to ciprofloxacin, clindamycin, erythromycin, gentamicin, oxacillin and penicillin G, and six strains of three filamentous fungi species: Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger. The nanoencapsulation of dapsone improved the inhibitory activity of the drug in both assays. In addition, the presence of chitosan in the formulations provided a better performance of the formulation in the case of S. aureus, while the influence of the nanoencapsulated drug was more pronounced in the antifungal activity. (C) 2016 Elsevier B.V. All rights reserved.