Enzyme immobilization on hydrogels: An overview on methods, interactions, and divers applications

Hydrogels have emerged as a versatile and promising class of materials for enzyme immobilization, offering a unique combination of biocompatibility, tunable porosity, and chemical flexibility that supports enhanced enzyme activity, stability, and reusability. Immobilizing enzymes within hydrogel matrices effectively addresses critical challenges associated with free enzymes, including low operational stability under extreme conditions, enzyme leaching, and mass transfer limitations. Hydrogels create a hydrated and protective microenvironment that preserves enzyme conformation and facilitates efficient substrate diffusion, thereby improving catalytic performance and extending operational lifespans. The integration of advanced hydrogel architectures-such as nanocomposites, stimuli-responsive systems, and smart polymers-has further contributed to enhancing the functional performance of immobilized enzymes. Immobilization strategies (adsorption, covalent bonding, entrapment, and encapsulation) could profoundly affect the properties/activity of immobilized enzymes on the hydrogels. Immobilization techniques like adsorption, covalent bonding, entrapment, and encapsulation can significantly impact the characteristics and activity of enzymes immobilized on hydrogels. This review provides a thorough examination of how these hydrogel-enzyme bioconjugates are synthesized, how they interact, and their wide-ranging uses, emphasizing their potential applications in various scientific and industrial areas. It covers recent progress and practical applications of hydrogel-enzyme conjugates in fields such as industrial biocatalysis, biosensing, environmental cleanup, medical diagnostics, and food processing. While notable progress has been achieved, challenges such as scalability, mechanical robustness, and cost-efficiency remain areas for continued development. Future efforts should focus on optimizing enzyme-support interactions and engineering multifunctional hydrogel systems to fully harness the potential of hydrogel-enzyme bioconjugates in sustainable and innovative biotechnological solutions.