Embedment of liposomes into chitosan physical hydrogel for the delayed release of antibiotics or anaesthetics, and its first ESEM characterization.

This work describes the characterization of an original liposomes/hydrogel assembly, and its application as a delayed-release system of antibiotics and anaesthetics. This system corresponds to drug-loaded liposomes entrapped within a chitosan (CS) physical hydrogel. To this end, a suspension of pre-formed 1,2-dipalmitoyl-sn-glycero-3-phosphocoline liposomes loaded with an antibiotic (rifampicin, RIF), an anaesthetic (lidocaine, LID), or a model fluorescent molecule (carboxyfluorescein, CF), was added to a CS solution. The CS gelation was subsequently carried out without any trace of chemical cross-linking agent or organic solvent in the final system. Liposomes within the resulting gelled CS matrix were characterized for the first time by environmental scanning electron microscopy. The release of drugs from the assembly was investigated by fluorescence or UV spectroscopy. The cumulative release profiles of RIF and LID (and also CF for comparison) were found to be lower from the "drug-in-liposomes-in-hydrogel" (DLH) assembly in comparison to "drug-in-hydrogel" (DH) system.