In some aspects, improved hydrogel copolymers (e.g., comprising itaconic acid and N-vinylpyrrolidone) are provided and may be used, e.g., for oral delivery of a therapeutic protein. In some embodiments, improved methods for loading a therapeutic protein (e.g., a high isoelectric point protein) into a hydrogel copolymer are provided, and may comprise incubating the therapeutic protein and the hydrogel in a reduced ionic strength loading solution. In some embodiments, use of the reduced ionic strength loading solution can result in hydrogel copolymer-therapeutic protein compositions that display improved pharmacokinetic attributes, e.g., improved loading and/or release of a therapeutic protein.
