Synthesis and Characterization of Gelatin Methacrylate Hydrogel Microparticles for Biomedical Applications

Delivery of oxygen, nutrients, and drugs from bulk hydrogel is limited by the dimension of the hydrogel. To alleviate this practical problem, hydrogel microparticles (HMPs) have recently attracted attention in the biomedical field for multiple applications like cell delivery, bioinks for 3D printing, and as building blocks in tissue engineering. Owing to the micrometer size (1 m to 1000 m) of the hydrogel, they can easily promote cell migration, improve mass transport, reduce fibrous encapsulation, and enhance vascularization. Our aim was to synthesize photo- polymerizable gelatin methacrylate (GelMA) HMPs as cell-laden scaffolds for bone tissue repair. Here, we present our preliminary results showing the synthesis of GelMA hydrogel with the relevant physical and chemical characterization. We also fabricated GelMA HMPs in various shapes and sizes with a 3D printer. The peaks corresponding to the methacrylate groups bonded to the gelatin backbone was confirmed by Nuclear Magnetic Resonance (NMR) spectroscopy revealed. Rheometry of the samples determined the Young’s modulus of the GelMA hydrogel to be approximately 60 ± 8 KPa. The SEM microstructure revealed a porous microstructure which is convenient for cell invasion and nutrient diffusion. The water retention property (swelling ratio) of the hydrogel demonstrated a 20-fold increase compared to dry GelMA. The printed GelMA HMPs had a high print fidelity for the size range of 500-1000 m. HMP bioinks are designed to flow under pressure yet remain adhesive enough to maintain a 3D shape during 3D printing. Our results prove the high print fidelity of HMP in various size and shapes. The fabricated GelMA HMPs can be potentially used as injectable biomaterials for tissue repair.