Multi-scaled polymersomes from self-assembly of octadecanol-modified dextrans

Lipid-conjugated polysaccharide vesicles in nano- and micro-scale were developed from amphiphilic octadecanol-modified dextrans (OMD) prepared by partial esterification of dextran with activated octadecanol-carbamate imidazole in a well-controlled manner. The critical aggregation concentration (CAC) of OMD adducts in aqueous phase varies, depending mainly on their octadecanol contents. Through supramolecular assembly of the OMD adducts comprising either 17 or 28 mol% octadecanol residues with respect to the anhydroglucopyranose units by the partial solvent displacement technique with the initial water content of DMSO/H2O solutions beyond a critical point, stable nano-scaled OMD assemblies were developed and characterized by the vesicle-like morphology. The dimension of polymersomes can be effectively controlled by the OMD composition as well as the initial water content. On the other hand, micro-scaled OMD polymersomes can be achieved by the double emulsion technique in a water/oil/water (w1/o/w2) manner. Both the contents of NaCl in aqueous solution as the w1 phase and of DMSO in DMSO/CHCl3 co-solvents as the organic phase, in which OMD was dissolved, are of great importance in controlling the polymersome morphology and size. These micro-scaled OMD polymersome walls are characterized by size-selective permeability capable of encapsulating large water-soluble cargoes while allowing transport of small polar species across the membrane, thereby rendering these unique colloidal particles of potential applications in biomedical technologies.