Reactive hydroxyapatite fillers for pectin biocomposites

•Injectable pectin hydrogels are produced by internal gelation with hydroxyapatite.•Hydrogels are developed with tunable gelling kinetics and rheological properties.•Hydrogels can be injected from small needles by minimal-invasive approaches.•Hydrogels can be dissolved with physiological solutions, to accelerate cell release.•L929 cells immobilized in pectin–hydroxyapatite hydrogels exhibited good viability.

In this work, a novel injectable biocomposite hydrogel is produced by internal gelation, using pectin as organic matrix and hydroxyapatite either as crosslinking agent and inorganic reinforcement. Tunable gelling kinetics and rheological properties are obtained varying the hydrogels' composition, with the final aim of developing systems for cell immobilization. The reversibility by dissolution of pectin–hydroxyapatite hydrogels is achieved with saline solutions, to possibly accelerate the release of the cells or active agents immobilized. Texture analysis confirms the possibility of extruding the biocomposites from needles with diameters from 20 G to 30 G, indicating that they can be implanted with minimally-invasive approaches, minimizing the pain during injection and the side effects of the open surgery.L929 fibroblasts entrapped in the hydrogels survive to the immobilization procedure and exhibit high cell viability. On the overall, these systems result to be suitable supports for the immobilization of cells for tissue regeneration applications.

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