Lyoprotectants modify and stabilize self-assembly of polymersomes

Polymersome formation in water was confirmed with average polymersome diameters of 237.2 ± 66.5 nm over 150 min. Empty polymersomes created by dissolving poly(ethylene glycol)-b-poly(lactic acid) in water increased to 4.63 ± 0.01 times their size after lyophilization, showing lack of long-term stability. The use of lyoprotectants, mannitol and inulin, to maintain particle size distribution (PSD) was studied. The incorporation of both molecules was confirmed and showed no detrimental effects on PSD during formation. Differences in moisture content were found after lyophilization between samples incorporating inulin and mannitol. After lyophilization, PSD of polymersomes lyophilized with inulin was maintained. Polymersomes lyophilized with mannitol showed a significant decrease in diameter, a potential advantage for delivery of therapeutics. It was hypothesized that lyoprotectants replaced water, maintaining polymersome structure under stressful processing conditions. The ability to reconstitute polymersome drug delivery carriers without altering size distribution is paramount to the creation of effective and efficient drug delivery systems.