# Octacalcium Phosphate/Calcium Citrate/Methacrylated Gelatin Composites: Optimization of Photo-Crosslinking Conditions and Osteogenic Potential Evaluation

## TL;DR

This study develops a composite material for bone grafting that improves structural stability while retaining the ability to form bone-like minerals.

## Contribution

The study introduces a 35% OCP/35% CC/30% GelMA composite with optimized photo-crosslinking for enhanced bone regeneration.

## Key findings

- The OCP/CC/GelMA composite showed enhanced initial structural stability in simulated body fluid.
- The composite retained its hydroxyapatite-forming ability despite reduced nucleation compared to pig Gel composites.
- The material is proposed as a stable scaffold for future bone regeneration research.

## Abstract

Bone grafting is essential for the regeneration of bone defects where natural healing is inadequate. Octacalcium phosphate (OCP)/calcium citrate (CC)/pig gelatin (pig Gel) composites promote hydroxyapatite (HAp) formation in simulated body fluid (SBF); however, the rapid degradation of pig Gel leads to their degradation in SBF within 7 d. To address this, we developed a 35% OCP/35% CC/30% methacrylated gelatin (GelMA) composite by leveraging the tuneable photo-crosslinking ability of GelMA to enhance the initial structural stability in SBF. However, the optimal synthetic photo-crosslinking conditions and the apatite-forming abilities of the OCP/CC/GelMA composite require investigation. In this study, we employed photo-crosslinking to synthesize homogeneous OCP/CC/GelMA composites with initial structural stability in SBF and evaluated their HAp-forming ability in SBF as an indicator of osteogenic potential, in comparison with the OCP/CC/pig Gel composites. Both GelMA- and pig Gel-based composites were prepared and immersed in SBF for 7 d to assess HAp formation. Although the OCP/CC/GelMA composite showed reduced HAp nucleation compared to the OCP/CC/pig Gel composites, it exhibited enhanced initial structural stability in SBF while retaining its HAp-forming ability. These findings highlight the OCP/CC/GelMA composite as a stable and promising scaffold for bone regeneration, laying the groundwork for further research.