Jacob Kotzenmacher

Microfluidic devices are excellent tools for fabricating polymer microcapsules. With a liquid core and a polymer shell, microcapsules are excellent vehicles for delivering drugs to target cells and tissues in the body with temporal control. Drugs with high water solubility can be loaded in the liquid core of microcapsules. The rate of drug release can be modulated by changing the chemical composition and thickness of the polymer shell. The objective of this project is to construct and evaluate a microfluidic device for the fabrication of microcapsules using two biodegradable polymers – poly(lactic-co-glycolic acid) (PLGA) and polycaprolactone (PCL). We constructed a microfluidic chip using the surface tension differences between polytetrafluoroethylene (PTFE) tubing – a hydrophobic polymer, and hydrophilic glass capillaries. The inner phase consisted of PLGA or PCL dissolved in dichloromethane. Polyvinyl pyrrolidine (PVP) or polyvinyl alcohol (PVA) were used as surfactants to stabilize emulsions formed by the inner oil phase and outer aqueous phase. Glycerol was chosen as a humectant in the inner phase and in the collection solution. By modifying parameters including phase composition and flow rate, PCL microcapsules with nearly uniform diameter and stable shells were prepared. Two fluorescent dyes, the hydrophobic Nile red and the hydrophilic fluorescein, were loaded into the middle and inner phases respectively to allow visualization of the polymer shell and the aqueous core by fluorescence microscopy. These results have validated the proper function of the microfluidic device, which produced stable polymer microcapsules carrying hydrophilic and hydrophobic payloads. Quantification of the release of model compounds is underway.