Comparative Evaluation of Calcium Chloride and Polyethylene Glycol 400 on Drug Loading in Human Plasma-Derived Exosomes: Insights from BCS Class II Drug Spironolactone

The aim of the current research was to evaluate the impact of calcium chloride (CaCl₂) and polyethylene glycol 400 (PEG 400) as encapsulation enhancer on the loading of a BCS Class II drug into human plasma-derived exosomes. Exosomes were isolated using differential ultracentrifugation, dialysis, and lyophilization. Spironolactone (SP), a BCS Class II drug was encapsulated into exosomes via freeze-thaw method. The impact of PEG 400 and CaCl₂ -used as loading enhancers on drug encapsulation efficiency, carrier loading capacity, colloidal stability, in-vitro drug release kinetics and biocompatibility on human embryonic kidney (HEK 293) cell lines was evaluated. Sodium dodecyl sulfate polyacrylamide gel electrophoresis confirmed the presence of exosomal surface markers (CD9, CD63, and CD81). Scanning electron microscopy confirmed spherical morphology. Optimized PEG 400-based SP loaded exosomal formulation showed significantly higher encapsulation efficiency (94 ± 2.5