EFFECTS OF IONIC STRENGTH ON STEALTH CATIONIC LIPOSOMES PRODUCTION IN MICROFLUIDIC CHIPS

Liposomes are self-assembled phospholipid vesicles that have been extensively investigated as nanocarriers for the sustained release of bioactive compounds, drugs and genetic material. Recent advances to improve nanocarrier’s body residence time include surface functionalization with poly(ethylene glycol) (PEG). However, the synthesis of monodisperse well-defined steric stabilized (stealth) liposomes remains a challenge. Herein, we describe a hydrodynamic focusing microfluidic process with tunable ionic strength to synthesize stealth cationic liposomes (SCL) for gene delivery applications. In this work, we benefit from microfluidics to assess real-time effects of increasing phosphate-buffered saline (PBS) concentrations from 10 to 50 mM on SCL stabilized with 1% of PEG. Under low ionic strength conditions, optical and cryogenic transmission electron microscopy (cryo-TEM) analyses demonstrated the presence of multi-sized aggregates. In contrast, higher ionic strength presented as a robust alternative to modulate lipid self-assembly kinetics and allow a tunable and reproducible synthesis of monodisperse SCL, which were characterized in terms of size distribution, mean diameter, zeta potential and polydispersity index (PDI). We demonstrate that ionic strength can be exploited as a microfluidic process variable to allow the continuous production of monodisperse (PDI<0.2) SCL of around 140 nm with monomodal size distributions and uniform features for advanced applications.