Sundar S.K.'s Talk

Apr 10, 2014 - 17:00

Apr 10, 2014 - 18:00

Creativity Hall (Room 118) Chemical Engineering

Seminars

Sundar S.K.

Abstract: Drug delivery using liposomes for targeting the afflicted areas of the host has attracted significant interest in the scientific community. Despite the development of various processes for liposome synthesis the application is limited due to issues related to process complexity and scale-up. Hence there is an urgent need of an alternative technique that can be scaled up to industrial scale. To this end we focus on the self assembly of lipid molecules leading to the formation of liposomes in the sub-100-nm range via microfluidics. We describe a novel technique to synthesize monodisperse liposomes in the sub-100 nm size range using a packed bed of colloidal particles which could also be used to simultaneously encapsulate a drug. The methodology involves drying lipids dispersed in an organic solvent in a capillary packed with colloidal particles which upon hydration with an aqueous buffer containing a drug leads to liposome formation with simultaneous encapsulation of the drug. Our experiments show that the size of the liposome is independent of the particle size or the pore size. The entrapment efficiency of the liposomes prepared by hydration using low volumes (~200 µl)of aqueous medium indicates 30% of its overall capacity. This makes the proposed process a promising technique for liposome synthesis. Finally we describe an automated process based on the packed bed process for continuous production of liposomes using alternate plugs of lipid and buffer interspersed by flow of nitrogen gas. In the second part we investigate the dewetting phenomenon leading to hole formation in solid supported lipid bilayers obtained via spin coating. The study involved lipid films of four different lipids dispersed in ethanol and chloroform on glass substrate to investigate the role of the nature of lipid solvent and film thickness on the characteristic length scale and the number density of the holes. For a fixed solvent and rotation rate the average size of the hole increased with dry film thickness while the number density decreased with the film thickness. However the measured hole sizes are about an order of magnitude lower than that predicted by the spinodal dewetting theory. The length scale of the holes were greater in case of ethanol compared to chloroform though the predicted trends are opposite. Our results indicate that despite the discrepancy the hole formation is primarily driven by the spinodal dewetting process. Keywords: Microfluidics Sub-100-nm Liposomes Single step Mondodisperse Packed bed Encapsulation Lipid bilayer