Droplet-based microfluidic synthesis of lipid vesicles containing quantum dots

Abstract

This paper describes a new droplet-based microfluidic platform for synthesis of small-sized (~10 μm) giant uni-lamellar vesicles containing quantum dots. To generate giant uni-lamellar vesicles (GUVs), we designed a simple microfluidic chip combining a parallel-flow channel with cross-flow channel. Previously, microfluidic-based uni-lamellar lipid vesicles have been synthesized by using T-junction and focusing channels. These approaches rely on partial surface treatment of channel, serially flowed fluids and off-chip process, thereby causing high complexity and contamination of lipid vesicles. In addition, dimension of uni-lamellar lipid vesicles is ranged from 10 to 120 μm. Due to the dimension of microfluidic device, the small sized lipid vesicles less than 10 μm cannot be easily synthesized. Here, we fabricated a simple microfluidic chip consisted of T-junction and cross flow region. Dimyristoylphosphatidylcholine (DMPC) was used for the construction of self-assembled membrane, in which the solvent of DMPC was octanol and octanol??chloroform solution. In the condition of octanol-chloroform solution, smaller droplets (diameters below 10 μm) were easily synthesized. We also found that the concentration of lipid was act as a primary role to determine mono dispersity as well as generate smaller droplets. Consequently mono dispersed droplets with a mean diameter of 10 μm were generated at the lipid concentration of 14 mg/ml. On the basis of these results, a synthesis of GUVs with a size below 10 μm was demonstrated by using microdroplet based device. To confirm encapsulation efficiency of nanoparticles, we synthesized GUVs containing quantum dots. This result will be useful to develop a new microfluidic platform for simple, rapid, continuous quantum dots containing GUVs synthesizer.