Chitosan-Coated PLGA Nanospheres for Improved Amphotericin B Delivery: Characterization, Mucoadhesion, and Cytotoxicity Assessment

In this study, we developed chitosan-coated PLGA nanospheres encapsulating amphotericin B (AmB) with the aim of enhancing its delivery profile while minimizing cytotoxicity. The nanospheres were prepared using the single emulsion solvent evaporation method, resulting in particles with a mean size of 204 ± 22 nm and a polydispersity index of 0.19 ± 0.01, indicating a monodisperse system. The encapsulation efficiency was high (93 ± 0.4%), likely due to the hydrophobic nature of AmB. Scanning electron microscopy confirmed the spherical morphology of the nanospheres. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses indicated that AmB was present in an amorphous state within the nanospheres, suggesting potential improvements in solubility and bioavailability. In vitro release studies in simulated gastric and intestinal fluids demonstrated the stability of the chitosan-coated nanospheres, with only 1.4% of AmB released over 6 h, indicating effective protection of the drug in the gastrointestinal environment. The cytotoxicity assays on Vero cells revealed that the nanospheres significantly reduced the toxicity of AmB, with cell viability remaining above 90% even at the highest drug concentration after 72 h of incubation. Furthermore, the mucoadhesion studies showed a strong interaction between the chitosan-coated nanospheres and mucin, which could enhance the retention time and absorption of AmB in the gastrointestinal tract. Overall, the results suggest that chitosan-coated PLGA nanospheres are a promising system for oral delivery of AmB, offering improved stability, reduced cytotoxicity, and enhanced mucoadhesion, potentially leading to better therapeutic outcomes in the treatment of fungal infections.