Plga 75 25 13 kd mw acid capped

Drug-free PLGA microspheres were prepared by using a double emulsion solvent evaporation method. PLGA 75/25 13 kD Mw acid-capped (Wako, Japan), 1 g was dissolved in 1 mL methylene chloride. Once dissolved, 100 μl of a 500 mg/mL trehalose in ddH₂O solution was added to the polymer solution to increase polymer porosity and then homogenized (VirTis Tempest I.Q.2) for 1 min at 10,000 rpm to create a water-in-oil (w/o) emulsion. Next, 4 mL of a 5% wt poly vinyl alcohol (PVA) solution was added to the emulsion, which was then vortexed (Scientific Industries Vortex Genie 2) for 1 min at maximum speed. The solution was then added to a 100 mL stirring bath of 0.5% PVA and stirred for 3 h to allow for solvent evaporation. After hardening, microspheres were washed with 1 L diH₂O and sieved for size, 20–63 μm. Microspheres were lyophilized (Labconco FreeZone 2.5) at <0.1 mBar and stored, desiccated, at −20 °C until further use. To illustrate adjustment of initial burst release, the drug-free PLGA microspheres were prepared ± prior polymer purification and ± the trehalose porosigen, as described in Supplementary Material.