On the Synthesis and Characterization of Biodegradable Dextran Nanogels with Tunable Degradation Properties

Hydrogels are widely investigated as carriers in drug delivery. To be suitable carriers for intracellular drug delivery, hydrogels should be small enough to be able to enter cells. This paper reports on the synthesis and characterization of both lipid coated and naked biodegradable hydroxyethyl methacrylated dextran (dex-HEMA) nanogels. Dynamic light scattering (DLS), atomic force microscopy, and transmission electron microscopy showed that lipid coated nanogels could be obtained by polymerization of an aqueous dex-HEMA solution entrapped in SOPC/DOTAP liposomes (SOPC and DOTAP, respectively, being 1-stearoyl-sn-glycero-3-phosphocholine and 1,2-dioleolyl-3-trimethylamonium propane chloride). Naked dex-HEMA nanogels were prepared by removing the lipid coating by Triton X100. DLS measurements on dex-HEMA nanogels stored in buffer at 37 °C revealed that the degradation time depended on the cross-link density of the nanogels: dex-HEMA nanogel prepared from dextran lowly substituted with HEMA degraded quickly, while it took days to weeks for nanogels prepared from highly substituted dextran. Furthermore, confocal laser scanning microscopy showed that SOPC/DOTAP coated dex-HEMA nanogels can be taken up by VERO-1 cells.