2.6. Stability Studies

The stability of empty and AG-loaded liposomes was studied for one month. Aqueous dispersions were kept at 4 °C and, at fixed time intervals, their physical and chemical stabilities were assayed: physical stability was checked by monitoring sizes, polydispersity index and ζ-potential, while chemical stability was determined by quantification of encapsulated drug by HPLC-DAD analysis.

The freeze-drying process in the absence of cryoprotectant and in the presence of 1% w/v of glucose or sucrose was also considered. Afterwards, lyophilization physical stability was checked for one month at 25 °C.

200 μL of LPs and CLPs dispersions were incubated at body temperature with a solution of human serum albumin (HSA, 40 mg/mL in PBS) for two hours under magnetic stirring to mimic in vivo conditions [32,33]. Physical stability of the formulations was evaluated using Dynamic Light Scattering, by controlling liposomes sizes at regular intervals.

The yield of the preparation of freeze-dried LPs-AG and CLPs-AG was calculated as the weight of the product obtained after the freeze-drying, compared to the weight of the components used in the reaction (3):