Design, Preparation, and Characterization of Thermoresponsive Hybrid Nanogels Using a Novel Ulvan-Acrylate Crosslinker as Potential Carriers for Protein Encapsulation

The aim of the present study is the design and development of thermoresponsive nanogels based on ulvan, a sulphated heteropolysaccharide of algal origins with unique biological and chemical properties. Hybrid nanogels are successfully synthesized by means of UV-initiated radical copolymerization of N-vinylcaprolactam with an ulvan derivate as a novel crosslinker. In nanogels, the ulvan-grafted poly(N-vinylcaprolactam) chains represent the thermoresponsive component. The most promising candidates, selected after a thorough physical-chemical characterization of nanogels in terms of size and responsivity to thermal variation at physiological conditions, are loaded with bovine serum albumin (BSA) as model bioactive compound. The developed nanogels display BAS loading efficiency values similar to those obtained by using synthetic crosslinkers, and thus indicating the suitability of the developed ulvan-acrylate to act as novel macromolecular crosslinker for thermoresponsive nanogels preparation.