Radiation-induced synthesis of nanogels based on poly(N-vinyl-2-pyrrolidone)—A review

• Radiation-induced synthesis of PVP nanogels.
• Irradiation of thermally collapsed PVP.
• Nanogels of intermolecular complexes based on PVP.
• Functionalization of PVP nanogels.
• Applications of PVP nanogels.

Nanogels are nanometer-scale two-component systems consisting of a permanent three-dimensional network of linked polymer chains, and molecules of a solvent filling the pores of this network. A number of synthetic routes have been developed for nanogels. One of them is based on intramolecular cross-linking of individual polymer chains and ionizing radiation is a suitable tool for initiation of this process. Poly(N-vinyl-2-pyrrolidone)—PVP—was one of the first polymers used to obtain intramolecularly cross-linked macromolecules using this method called preparative pulse radiolysis. This review summarizes radiation-based techniques used for synthesis of PVP-derived nanogels starting from preparative pulse radiolysis, through irradiation of thermally collapsed PVP and cross-linking in microemulsion up to formation of PVP based interpolymer complexes. In addition, possible practical applications of PVP-based nanogels have been presented mainly in the biomedical field. Nanogels functionalized with (3-N-aminopropyl)methacrylamide hydrochloride may serve for bioconjugation and drug transportation into the cells. Nanogels of interpolymer complexes are expected to be mucoadhesive and be able to bind cationic drugs electrostatically and non-polar drugs via solubilization in the hydrophobic cores.