Preprint for publication "Multifunctional implantable hydrogels: Smart platforms at the forefront of biomedical innovation"

Hydrogels are a transformative class of biomaterials with high water content, intrinsic biocompatibility, and tunable mechanical, chemical, and biological properties. These three-dimensional polymeric networks closely mimic the extracellular matrix, making them ideal for implantable biomedical applications. This review provides a comprehensive overview of implantable hydrogel technologies, focusing on critical physicochemical and biological features that determine clinical performance. Recent advances in additive manufacturing fabrication techniques, including 3D and 4D printing, are explored alongside innovations in hydrogel ink formulations designed to enhance mechanical robustness, shape fidelity, and biological functionality. Special attention is given to the infection-preventive roles of hydrogels, both as implant coatings and injectable platforms. Surface modification strategies—covalent and non-covalent—are discussed in the context of improving biocompatibility and preventing microbial colonization. Injectable hydrogels are further examined for their antimicrobial efficacy, particularly within stimuli-responsive drug delivery systems and multifunctional platforms, with an emphasis on translational challenges from in vitro studies to clinical application. The regenerative potential of hydrogels is also highlighted, especially in bone tissue engineering, focusing on osteoconductivity, osteoinductivity, vascularization, and regulatory considerations. Additionally, implantable hydrogel-based patches for real-time health monitoring are evaluated, including emerging biosensing technologies and their integration into clinical practice. Despite significant progress, challenges remain in large-scale manufacturing, long-term stability, and regulatory approval. Future perspectives emphasize the development of smart, multifunctional hydrogels with integrated biosensing and responsive therapeutic delivery, highlighting their potential to advance personalized medicine and improve patient outcomes.