Spray-dried powders were reconstituted with purified water at approximately 0.5 mg/mL PLGA by shaking for 30–60 min and passed through a 1.0 μm glass microfiber syringe filter to remove agglomerated PLGA particles and incompletely dissolved matrix excipients. The filtered particle suspensions were analyzed by dynamic light scattering (Zetasizer Nano ZS, Malvern Instruments; Worcestershire, UK; λ = 633 nm, 25.0 ± 0.1°C, backscatter mode, cumulants fit).