Scalable Synthesis of Biodegradable Polymer Particles

PLG particles were formed using a single oil-in-water emulsification followed by solvent extraction method, reported previously by our group^{23 (link)–25 (link)}. Briefly, 50:50 PLG was dissolved in dichloromethane at 4% (wt/wt). 0.6 mL of the 4% PLG solution was added dropwise to 4 mL of an aqueous solution of 0.2% (wt/v) poly(vinyl alcohol) (PVA) or modified PVA and emulsified at 11,000 rpm for 5 minutes using a Kinematica PT3100D homogenizer. Particle formation occurred by adding the emulsion to 16 mL of ultrapure water and then stirring the mixture for 1 hour. The particles were then passed through a 40 μm filter and collected via centrifugation at 250×g. The particles were then washed 4 times by suspending them in ultrapure water and then collecting them via centrifugation (250×g). Washed particles were frozen at −20°C and lyophilized overnight. Recovered particles were stored under vacuum in a dry environment at room temperature. For coumarin 6 loaded particles, all conditions were the same except coumarin 6 was added to the organic phase at 0.3 mg/mL.
Particle mass yield was calculated by dividing the mass of recovered particles by the mass of PLG emulsified. Particle mass yield was calculated according to equation 2.
$$\mathit{\text{Mass}} \mathit{\text{Yield}} \left(\text{\%}\right)=\left(\frac{M_{PT}}{M_{PLG}}\right)\text{*}100$$
Where M_PT is the mass of particles recovered from the emulsion, M_PLG is the mass of PLG added to the emulsion.