Preparation of liposomes: a novel application of microengineered membranes - investigation of the process parameters and application to the encapsulation of vitamin E

Abstract

Liposomes with a mean size of 59-308 nm suitable for pulmonary drug delivery were prepared by the ethanol injection method using nickel microengineered flat disc membranes with a uniform pore size of 5-40 mm and a pore spacing of 80 or 200 mm. An ethanolic phase containing 20-50 mg ml 21 phospholipid (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or Lipoid1 E80), 5-12.5 mg ml 21 stabilizer (cholesterol, stearic acid or cocoa butter), and 0 or 5 mg ml 21 vitamin E was injected through the membrane into an agitated aqueous phase at a controlled flux of 142-355 l m 22 h 21 and a shear stress on the membrane surface of 0.80-16 Pa. The mean particle size obtained under optimal conditions was 84 and 59 nm for Lipoid E80 and POPC liposomes, respectively. The particle size of the prepared liposomes increased with an increase in the pore size of the membrane and decreased with an increase in the pore spacing. Lipoid E80 liposomes stabilized by cholesterol or stearic acid maintained their initial size within 3 months. A high entrapment efficiency of 99.87% was achieved when Lipoid E80 liposomes were loaded with vitamin E. Transmission electron microscopy images revealed spherical multi-lamellar structure of vesicles. The reproducibility of the developed fabrication method was high.

pH-Sensitive Micelles for Targeted Drug Delivery Prepared Using a Novel Membrane Contactor Method

“…Table 3 and Figure 6. A similar linear relation between the particle size and pore size of microengineered membrane was obtained in fabrication of liposomes 39 and membrane emulsification. [40][41] The results clearly show that the micelle size can be controlled by the membrane pore size.…”

Formation of size-tuneable biodegradable polymeric nanoparticles by solvent displacement method using micro-engineered membranes fabricated by laser drilling and electroforming

“…However, higher influx of PCL into the aqueous phase leads to higher supersaturation, which explains why the Zaverage only slightly increased from 196 to 200 nm. Similar trends were observed for other NPs formed in membrane contactors [30,41,45,46].…”

“…At smaller or aq V / V ratios, the concentration of THF in the aqueous phase increased at higher rate, which resulted in lower supersaturations and the formation of larger NPs. In addition, at higher THF concentrations in the aqueous phase, the rate of Ostwald ripening was higher due to greater solubility of PCL, which may also play a role in the formation 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 [39] in the preparation of SiO 2 NPs, Huang et al [40] in the preparation of ZnO NPs and Laouini et al [28,41,42] in the production of liposomes and polymeric micelles.…”

Preparation of biodegradable polymeric nanoparticles for pharmaceutical applications using glass capillary microfluidics

“…Therefore, a larger number of nuclei will lead to smaller size of NPs. The smaller particle sizes at higher aqueous-to-organic volume ratios were also obtained by Laouini et al (2013aLaouini et al ( , 2013bLaouini et al ( , 2013c in the production of liposomes and polymeric micelles in membrane contactors and by Jahn et al (2010) in the formation of liposomes in planar flow focusing microfluidic mixers.…”

“…Membrane micromixing is an alternative strategy of controlled mixing at molecular scale that was combined with nanoprecipitation to produce inorganic nanoparticles (Jia and Liu, 2013), liposomes (Laouini et al, 2013a), micelles (Laouini et al (2013c), and PCL nanoparticles (Khayata et al, 2012). In a membrane-dispersion reactor, one liquid phase is dispersed through a microporous membrane into another liquid under controlled shear conditions and injection rate.…”