Novel 3D integrated microfluidic device: Design, construction, and application to the preparation of liposomes for vaccine delivery

As a kind of nanovesicles, liposomes are considered to be the most promising delivery vehicles for drugs and vaccines. The preparation of liposomes using microfluidic chips is one of the most effective and feasible methods. Removal of solvents and non-encapsulated drugs is usually required after liposome formation, which will affect the storage stability and medical safety of liposomes, thus hindering their industrial production and clinical application. Therefore, innovative preparation techniques with multiple integrated functions are of practical significance to address the challenges of traditional and latest developed liposome preparation technologies. A novel three-dimensional integrated microfluidic device (3D-mf device) reported here can be used as a continuous process flow system for liposome preparation and purification. The microchannel array of the microdevice is 4 x 3, and the computational fluid dynamics simulation is used to determine that the ratio of the four filter area channels is 1: 0.75: 0.5: 0.2. Drug-loaded liposomes with an average particle size of 208 nm and polydispersity index (PDI) of 0.211 were prepared by adjusting the total flow rate (TFR) and flow rate ratio (FRR). The removal rates of ethanol and polyinosinic acid: polycytidylic acid [poly (I: C)] after a single cycle were 66.8 % and 56.3 %, respectively. The size distribution and zeta potential of liposomes keep stable within 28 days. Finally, in an immunization study in rats, hemagglutination inhibition titers (HI, >= 512) were found to be significantly higher than those required for protection after two rounds of immunization with 6 mu g of hemagglutinin from a split influenza vaccine with poly (I: C) liposomes. This innovative integrated device shows the potential for industrial production of nano-pharmaceutical applications.