ENZYME-RESPONSIVE HYDROGELS FOR TARGETED THERAPEUTIC DELIVERY AND DIAGNOSTIC APPLICATIONS

Abstract

Enzyme-responsive hydrogels (ERHs) represent a promising class of smart biomaterials designed to exploit pathological enzymatic activity for precision medicine. In this study, chitosan, hyaluronic acid, polyethylene glycol diacrylate (PEGDA), and gelatin methacryloyl (GelMA) were functionalized with matrix metalloproteinase (MMP)-cleavable peptide linkers to develop multifunctional hydrogels for targeted drug delivery and diagnostic imaging. Physicochemical characterization confirmed a highly porous morphology, excellent swelling behavior, and stable viscoelastic properties suitable for biomedical use. Enzyme-triggered degradation studies demonstrated selective hydrogel disassembly in the presence of MMP-2 and hyaluronidase, enabling controlled and site-specific release of encapsulated doxorubicin (DOX). Drug release assays revealed accelerated and sustained delivery under enzyme-rich conditions, resulting in significant cytotoxicity against U87-MG glioblastoma cells while sparing normal fibroblasts, thereby confirming the therapeutic selectivity of the system. In parallel, diagnostic evaluation using fluorescein isothiocyanate (FITC) and superparamagnetic iron oxide nanoparticles (SPIONs) showed strong intracellular fluorescence and enhanced T₂-weighted MRI contrast, validating the hydrogels’ dual theranostic capability. Biocompatibility assessments confirmed minimal hemolysis and cytotoxicity of blank hydrogels, while long-term stability studies revealed >94% drug retention over 28 days, demonstrating structural integrity and storage feasibility. Collectively, these findings highlight the potential of ERHs as next-generation theranostic platforms capable of integrating targeted therapy with real-time diagnostic monitoring. Despite challenges in clinical translation such as variability in enzymatic expression and scalability this work provides a strong foundation for developing precision biomaterials to address complex diseases like cancer and chronic wounds.