Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

Abstract

Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs) via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter) of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadieneb-poly(ethylene oxide) (PB-PEO)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation. OPEN ACCESSPolymers 2013, 5 1103

New Developments in Liposomal Drug Delivery

“…Different ratios of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC; phospholipid component) and polybutadiene-b-poly(ethylene oxide) (PB-PEO; block copolymer) resulted in self-assembled nanoscale HLs using the thinfilm hydration and extrusion techniques. 329 Quinteros et al used either mucoadhesive polymers (sodium hyaluronate or carboxymethylcellulose) or poloxamers to prepare HLs encapsulating the hypotensive melatonin analogue 5-methoxycarbonylamino-N-acetyltryptamine. The HLs composed of a bioadhesive 0.2% sodium hyaluronate proved to be most beneficial at reduction of the intraocular pressure in rabbit eyes.…”

Polymersome-Based Drug-Delivery Strategies for Cancer Therapeutics

“…These recently studied nanostructures (consisting of both polymers and lipids) not only have excellent robustness and tunable structural properties of polymersomal formulations but also retain the liposomes’ biocompatibility and biofunctionality [84,85]. A recent study demonstrates that targeting cancer-cell receptors can be achieved more efficiently using HLPs compared with polymersomes [86].…”

“…Electroformation [52,84], film rehydration followed by extrusion [84,87], and particle fusion (liposomes and polymersomes) using salt and agitation [88] have been used to prepare HLPs. The major challenge with HLP preparation is the heterogeneity of the formed nanovesicles.…”

“…Due to the inherent structural differences between lipids and polymers, the formation of mixed vesicles is possible (Figure 4). Depending on the amounts of polymers and lipids, lipid-rich domains in a polymer-rich membrane (Figure 4A), polymer-rich domains in lipid-rich membranes (like lipid rafts in cell membranes; Figure 4B) and membranes with homogenously distributed lipids and polymers (Figure 4C) are observed [52,84,87]. In extreme cases, phase separation is also possible, forming separate liposomes and polymersomes (Figure 4D).…”

Biophysics and Thermodynamics: The Scientific Building Blocks of Bio-inspired Drug Delivery Nano Systems

“…Namely, the metastable phases of mixed liposomal membranes control the release of the encapsulated drug (9). Furthermore, according to the proposed balance of the physicochemical/thermodynamic characteristics of nano systems, there is a strong interplay between their curvature (morphology) and their thermal behavior because the observed metastable phases are entropic traps that govern their functionality (11,12). These metastable phases must be probed during the pre-formulation studies in order to develop innovative nanocarriers with complete knowledge of their characteristics and produce safe and effective medicines.…”