(433c) Transmission of Microgel Particles Through Porous Membranes

Cross-linked poly(N-isopropylacrylamide) (PNIPAM) microgel particles could potentially be used as drug delivery systems. When used for such biomedical applications, these need to be in a highly pure form. Dialysis and centrifugation are the two most commonly used purification methods. Membrane filtration techniques such as ultrafiltration (UF) and microfiltration (MF) could also be used as purification methods. The microgel particles are stimuli-responsive and therefore their transmission behavior through porous membranes is significantly affected by operating and process variables. This study examines some of the factors affecting the transmission of 300~900 nm PNIPAM microgel through 0.2 micron microfiltration, and 3 and 50 kDa MWCO ultrafiltration membranes. The particles were labeled with a fluorophore to enhance their detectability and measurability. The observed effects are explained in terms of physicochemical properties of the microgel such as hydrodynamic radius and structural flexibility. The observations and inferences of this study are likely to be useful for designing and developing membrane based techniques for purifying microgels for biomedical application.