Abstract
Nanogels/microgels are intramolecularly crosslinked particles with submicron diameters that can swell in a suitable solvent due to their three-dimensional network structure. Nanogels provide beneficial features such as flexibility, biocompatibility, high stability and swelling, fixed shape, large surface/volume ratio, fast stimuli-responsive behavior, etc. Therefore, there is growing interest to further elaborate nanogel formulations in preclinical applications as therapeutics, diagnostics, or nanosensors. However, conventional nanogel synthesis methods may end up with nanogels containing toxic residuals, e.g., initiator, crosslinking agent, and fragments which possess a major disadvantage in biomedical applications requiring tedious purification steps. This chapter reviews the synthesis of nanogels by irradiation of dilute aqueous polymer solutions to induce intramolecular crosslinking by gamma rays or accelerated electrons. This simple, ecofriendly, and cost-effective manufacturing method eliminates the purification step and provides the possibility to produce clean nanogels with desired sizes at room temperature. In the formation of nanogels, the degree of crosslinking can be controlled by polymer solution properties as well as operational parameters such as dose rate of radiation source and total absorbed dose. The method can be applied to many water-soluble polymers, copolymers, or interpolymer complexes for the development of nanogels with desired sizes and properties.