One-Step Synthesis of Cytocompatible Brushite-Mineralized Gellan Gum/Alginate Microgels via a Temperature-Controlled...

Injectable bioactive microgels (MGs) are in high demand in minimally invasive bone regeneration, but their fabrication presents significant challenges. Specifically, creating composite MGs that are structurally stablerequiring high polymer concentrationsand containing a bioactive mineral phase is technologically difficult due to high viscosity, leading to inconsistent particle formation and system clogging. Our objective was to develop a novel temperature-controlled emulsification method to overcome these limitations and to produce and characterize MG from a brushite-mineralized highly concentrated gellan gum/sodium alginate (GG/SA). The setup allowed us to successfully produce uniform spherical MG with a controllable mineral content of up to 30% and a mean diameter below 100 μm. SEM/EDS, FTIR, XRD, and TG analyses confirmed the successful incorporation of a nanocrystalline brushite phase, which provided significant structural stability to MGs. In vitro assays demonstrated that all MGs are cytocompatible with MG63 osteoblast-like cells. Cell culture experiments in dynamic conditions revealed that the mineralized MGs support cell adhesion and spreading, contrasting with the nonmineralized controls, where no cell anchorage was observed. These findings demonstrate that precise temperature control is a successful strategy for processing high-viscosity GG/SA solutions into uniform MGs. The resulting materials combine the structural and bioactive benefits of a nanocrystalline brushite phase with the established biocompatibility of a GG/SA matrix. Ultimately, this work establishes an accessible and versatile temperature-controlled fabrication platform. While successfully demonstrated here for GG/SA/brushite composites, this setup can be broadly applied to process other high-viscosity, thermoresponsive biopolymers, opening new avenues for the tunable production of advanced MGs in tissue engineering.