Formation of solid lipid nanoparticles in a microchannel system with a cross-shaped junction

This work presents a novel method for generating solid lipid nanoparticles (SLNs) in a microchannel system with a cross-shaped junction formed by a main microchannel and two branches. A lipid solution by dissolving the lipid in a water-miscible organic solvent was passed through the main channel, while an aqueous surfactant solution was introduced into the branches simultaneously. These two liquids met together at the cross-shaped junction and passed along the main channel. The solvent diffused from the lipid solution stream into the aqueous phase, which resulted in the local supersaturation of lipid and thus led to the formation of SLNs. The flow behaviors of lipid and aqueous phase zones were measured by a digital inversion microscope system. The mean particle diameter and the particle size distribution of the obtained SLNs were measured by dynamic light scattering (DLS) method and the particle morphology was examined by transmission electron microscopy (TEM). The effects of liquid flow velocity and lipid concentration on the properties of SLNs were investigated experimentally. The formation mechanism of SLNs in the present microchannel system was discussed and analyzed.