Figure 43 Schematic of the HGSM synthesis (left) and HGGelMA construction (right).[151]
The water-soluble ultraviolet PI Irgacure 2959 has been widely used in cell encapsulation and tissue engineering,[152-154] however, there are significant limitations to its application. Firstly, UV light has been known to be harmful for delivered cells and host tissues, secondly, its solubility in water is relatively poor.[152, 155-156] Thus, the limitations of UV sources can be avoided by employing PI which could match to visible light. Lithium acylphosphinate salt (LAP) as a visible light PI possesses fine water solubility and allows cell encapsulation at lower PI concentrations, enabling efficient photopolymerization compared to Irgacure 2959. Monteiro et al.[157] prepared the gelatin methacryloyl (GelMA) hydrogels encapsulating odontoblast-like cells by using dental curing devices (DL) with emission wavelength in visible light range, as shown in Figure 44. The results show that short-time exposure to DL did not significantly affect cell survival, simultaneously, preparation of GelMA hydrogels by DL source is faster than UV source, and showed higher cellular activity with larger pore sizes.