Biopolymer-based microgels/nanogels for drug delivery applications

Polysaccharide-based microgels/nanogels have high water content, functionality, biocompatibility, tunable size from submicrons to tens of nanometers, large surface area for multivalent bioconjugation, and interior network for the incorporation of therapeutics. They are also abundant in nature, renewable, nontoxic, and relatively cheap. These unique properties offer great potential for the utilization of polysaccharide-based microgels/nanogels in tissue engineering, biomedical implants, bionanotechnology, and particularly, drug delivery. For the preparation of effective polysaccharide-based microgels/nanogels, various synthetic strategies based on chemical and physical crosslinking methods have been developed. They include heterogeneous polymerization, continuous extrusion, precipitation in water, micromolding and microfluidic preparation, spray drying, supramolecular self-assembly, and self-complexation. In addition, various methods to modify biopolymers have been explored, including methacrylation and covalent grafting by free radical polymerization (FRP), controlled/living radical polymerization (CLRP), and ring opening polymerization (ROP).