Enhancing bioink potential of hyaluronic acid by microwave-induced methacrylation

Abstract

This study reports the development of a light-curable methacrylated hyaluronic acid (HAMA) synthesized using microwave irradiation. The methacrylation process was carried out with AEMA as the methacrylating agent via an EDC/NHS protocol at varying microwave energy levels and compared comprehensively with those synthesized using the conventional heating method. The HAMA synthesis by microwave was optimized by applying different power levels (100 W, 250 W, and 800 W). The products were characterized by 1H NMR to determine the degree of methacrylation (DoM). The microwave-assisted synthesis significantly reduced the reaction time from 24 h to 6 min, improved reaction efficiency, and shortened the purification period from 3 days to 1 day. Additionally, it enhanced the mechanical, rheological, and swelling properties of the resulting hydrogels. The highest DoM was achieved at 78 % for HAMA-100 hydrogels synthesized at 100 W microwave energy. Rheological analysis demonstrated that microwave-assisted HAMA hydrogels could withstand nearly 100 % strain, outperforming those produced by conventional methods. This indicated the presence of an improved energy distribution mechanism at the molecular level within the polymer network structure of the microwave-assisted hydrogels. It was also observed that the microwave-assisted hydrogels exhibited strain-hardening behavior, ensuring the stability of bioactive structures in bioinks. Furthermore, the printing conditions for HAMA-100 gels were optimized in terms of printing pressure and speed. These findings highlight the significant role of microwave energy in achieving superior hydrogel properties, making it a promising green method for preparing bioinks for 3D printing applications.