Research Progress in Smart Hydrogel-Based Colloidal Systems for Osteoporosis Treatment

Osteoporosis is characterized by bone mass loss and deteriorated bone microarchitecture. Conventional pharmacological and hydrogel‑based therapies are limited by low bioavailability, adverse reactions, structural instability and poor drug‑release performance. Smart‑hydrogel‑based colloidal systems achieve spatiotemporally precise drug delivery through diverse stimuli-responsive mechanisms. They remodel the bone microenvironment, regulate osteoimmune balance, and restore osteoblast‑osteoclast coupling through scavenging reactive oxygen species, modulating macrophage polarization, inhibiting osteoclasts and promoting osteogenic differentiation. Despite promising preclinical outcomes including favorable biocompatibility and regenerative capacity, their clinical translation remains challenging. This review summarizes stimuli-responsive mechanisms, material properties, target‑cell effects and recent advances in such smart colloidal systems to facilitate further osteoporosis‑oriented research and translational progress.