Effect of Viscosity and Molecular Weight of PLGA on Microparticle Characteristics Via Microfluidics

Using droplet microfluidics to synthesize biodegradable microparticles for controlled drug delivery applications is advantageous over batch-emulsification techniques due to the formation of highly monodisperse particles. Changing the fluid composition, flow conditions, and junction geometry of a microfluidic device, result in varying effects on the characteristics of the formed particles, and understanding these effects is necessary to effectively form drug-loaded microparticles. This project uses a single emulsion Dolomite hydrodynamic flow focusing chip to prepare poly(lactic-co-glycolic acid) (PLGA) microparticles to determine how the viscosity of the PLGA solution and molecular weight of PLGA affect microparticle characteristics. The focus on PLGA is due to its biodegradability and established use in controlled drug delivery applications. Flow rates of the continuous phase (aqueous poly(vinyl) alcohol (PVA) solution) and dispersed phase (PLGA in dichloromethane (DCM)) were set and remained constant for all experiments, with the molecular weight of PLGA varying from 7,000 to 54,000 Da. After droplet solidification, the particles were imaged using Scanning Electron Microscopy (SEM) to measure particle diameter using a Matlab code, and images taken during droplet collection were analyzed to measure droplet diameter using ImageJ. From these measurements, we determined that the microparticles were monodisperse, with a coefficient of variance <0.05. Comparing the average diameters, we found that as molecular weight increased, particle size increased, but viscosity did not affect droplet size for the range of PLGA and microfluidic chip used.