Hydrogels in Tissue Engineering and Drug Delivery: A Comprehensive Review

Abstract

Hydrogels are highly hydrated three-dimensional polymeric networks that have emerged as versatile biomaterials for tissue engineering and drug delivery due to their excellent biocompatibility, tunable mechanical and physicochemical properties, and close resemblance to the native extracellular matrix (ECM). In tissue engineering, hydrogels act as bioactive scaffolds that support cell adhesion, proliferation, differentiation, and vascularization. Their adjustable stiffness, porosity, and controlled biodegradability facilitate the regeneration of various tissues, including skin, cartilage, bone, and neural tissue. In drug delivery, hydrogels function as intelligent reservoirs capable of sustained, localized, and stimuli-responsive (e.g., pH, temperature, redox, enzymatic, or light) release of therapeutic agents, enhancing treatment efficacy while minimizing off-target effects. Recent advances in self healing, injectable, nanocomposite, and 3D/4D bioprinted hydrogels along with the integration of bioactive molecules and cell-laden constructs have further expanded their potential for clinical translation. This review summarizes key design principles, emerging material innovations, and major translational challenges, highlighting the growing impact of hydrogels in regenerative medicine and precision therapeutics.