Production of PEGylated Vancomycin-Loaded Niosomes by a Continuous Supercritical CO₂ Assisted Process

Niosomes are arousing significant interest thanks to their low cost, high biocompatibility, and negligible toxicity. In this work, a supercritical CO₂-assisted process was performed at 100 bar and 40 °C to produce niosomes at different Span 80/Tween 80 weight ratios. The formulation of cholesterol and 80:20 Span 80/Tween 80 was selected to encapsulate vancomycin, used as a model active compound, to perform a drug release rate comparison between PEGylated and non-PEGylated niosomes. In both cases, nanometric vesicles were obtained, i.e., 214 ± 59 nm and 254 ± 73 nm for non-PEGylated and PEGylated niosomes, respectively, that were characterized by a high drug encapsulation efficiency (95% for non-PEGylated and 98% for PEGylated niosomes). However, only PEGylated niosomes were able to prolong the vancomycin release time up to 20-fold with respect to untreated drug powder, resulting in a powerful strategy to control the drug release rate.