Nanosized gel particles (nanogels) are of interest for a variety of applications, including controlled release of drugs and single-molecule encapsulation. Here, we employ the cores of nanoscale liposomes as reaction vessels to template the assembly of calcium alginate nanogels. For our experiments, a liposome formulation with a high bilayer melting temperature (Tm) is formed with sodium alginate encapsulated within and suspended in an aqueous buffer containing calcium chloride. The entry of divalent calcium ions into the liposomal core to crosslink the alginate chains within is mediated by heating the sample to temperatures in the vicinity of Tm, at which point transbilayer permeability is known to be increased. Subsequently, the lipid bilayer covering the gel is removed by addition of a detergent. The resulting alginate gels have a size distribution consistent with that of the template liposomes (~120-200 nm), as confirmed by transmission electron microscopy (TEM) and by multi-angle laser light scattering (MALLS) coupled with asymmetric flow field-flow fractionation (AF4). We have synthesized nanogels of different average sizes by varying the template dimensions, and have demonstrated that the gel size can be further tuned after synthesis by the addition of monovalent salt to the solution.
Pub Type: Journals
Alginate, Liposome, Nanoparticle, Self-Assembly, Templating