Recent advances and challenges of injectable hydrogels in drug delivery

Injectable hydrogels, serving as multifunctional biomaterials, exhibit exceptional shear-thinning behavior, tunable mechanical properties, and biocompatibility, attributed to their dynamic porous network structure and biomimetic microenvironment characteristics. It can be used as a drug carrier to achieve precise delivery and controlled release, and regulate cell behavior through biomimetic microenvironment, which has important application prospects in minimally invasive therapy and regenerative medicine. This review systematically describes their classifications, preparation methods, functional modifications, performance optimization and the latest advances including drug and cell delivery, and tissue engineering. Moreover, the current challenges associated with their clinical translation are also discussed, along with strategies to overcome these hurdles. Finally, the future research directions of injectable hydrogels are outlined, with an emphasis on enhancing their clinical applicability and overcoming current technological and clinical barriers to promote the widespread use in precision medicine and personalized therapies. This work will provide valuable insights for the design and application of injectable hydrogel-based biomaterials in biomedicine. • Injectable hydrogels enable precise drug delivery with controlled release kinetics. • Shear-thinning behavior of injectable hydrogels facilitates smooth injection and rapid self-healing post-administration. • In situ gelation ensures localized drug release at target sites. • Long-term stability and tunable gelation kinetics remain critical challenges. • Clinical translation necessitates overcoming manufacturing and regulatory barriers.