Characterization of Nanoscale Loaded Liposomes Produced by 2D Hydrodynamic Flow Focusing

This
paper presents the continuous flow formation by two-dimensional
(2D) hydrodynamic flow focusing (HFF) of nanosized liposomes in microfluidic
systems. The size distribution and concentration of the nanosized
liposomes, as well as the polydispersity index (PDI) and zeta potential
(ZP) of the liposomal dispersions, were investigated under various
flow rate ratios (FRRs) and lipid formulations, by the selective incorporation
of either positively charged DDAB (didodecyl-dimethylammonium bromide)
or negatively charged DOPG (1,2 dioleoyl-sn-glycero-3-
phosphoglycerol) lipids to the main bilayer DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) constituent. The challenges
of encapsulating an FITC (fluorescein isothiocyanate)-labeled LC-TAT
peptide (long chain of transactivator of transcription peptide), which
plays a direct role in the HIV regulation and transcription, overcame
and could be achieved via one-step nanoliposomes synthesis, in order
to validate the potential of this device as an all-in-one nanoparticle
synthesis and loading platform. Liposomes with sizes ranging between
60 to 800 nm were produced with low polydispersity and high particle
throughput from alteration of the flow rate ratio and lipid concentration.
We introduced the use of nanoparticle tracking analysis (NTA) to estimate
for the first time the throughput of microfluidic synthesized liposomal
NPs by measuring quantitatively the concentration of the synthesized
particles at the outlet. These measurements showed that stable and
unilamellar liposomes are generated at a maximum concentration of
1740 × 108 particles/mL in less than 2 min, with higher
FRR enabling the most rapid generation of liposomes with similar diameter
and significant lower polydispersity index than those obtained by
other batch techniques.