Development of cationic liposomes/DNA complexes in microfluidic system for applications in gene delivery

Abstract

This project studies the formation of complexes by electrostatic interactions between plasmid DNA (pDNA)(negatively charged) and cationic non-viral vectors. Gene delivery is a promising method for treating different diseases; however, the efficient delivery of the plasmid DNA into the cell nucleus requires nucleic acid protection against nucleases and interstitial fluids. In this context, aiming the delivery of nucleic acids to target cells with high transfection efficiencies, a wide variety of cationic non-viral vectors has being studied, such as cationic liposomes, self-assembled phospholipid aggregates that mimic the cell membrane. The spontaneous complexation process between pDNA and the cationic nanocarrier depends on the carrier characteristics, molar charge ratio between positive charges from the carrier and negative charges from the pDNA (R+/-), the temperature of complexation, solution concentrations, among others, and complexes with different characteristics can be obtained, resulting in different biological behavior. Currently, the microfluidic method emerges as a promising alternative to produce non-viral complexes with a narrow particle size distribution and polydispersity with reproducibility allowing further gene transfection studies, following the requirements for applications in gene therapy and DNA vaccination. Two geometries of a hydrodynamic flow focusing microfluidic devices will be explored. First, we will investigate the formation of nanoparticles in one step, with a middle stream composed of the lipid solution in ethanol, which is compressed by two side streams, composed of aqueous genetic material solution. Next, we will study microfluidic devices with multiple entries, so the formation of liposomes primarily and the complexation with pDNA can occur in a subsequent stage. The operating variables are evaluated: (I) superficial velocity of flow in the microreactor, (II) solutions concentration, (III) temperature, (IV) molar ratio between positive and negative charges, from pDNA and liposomes, respectively. The response variables will be the average diameter, zeta potential, and polydispersity of the particles. So, the proposed project intends to show the potential of using microfluidic device with the hydrodynamic flow focusing technique for the continuous formation of complexes between pDNA and liposomes, non-viral cationic nanocarrier, for applications in gene delivery and DNA vaccination. (AU)