Synthesis and Characterization of Types A and B Gelatin Methacryloyl for Bioink Applications

Abstract

Gelatin methacryloyl (GelMA) has been increasingly considered as an important bioink material due to its tailorable mechanical properties, good biocompatibility, and ability to be photopolymerized in situ as well as printability. GelMA can be classified into two types: type A GelMA (a product from acid treatment) and type B GelMA (a product from alkali treatment). In current literature, there is little research on the comparison of type A GelMA and type B GelMA in terms of synthesis, rheological properties, and printability for bioink applications. Here, we report the synthesis, rheological properties, and printability of types A and B GelMA. Types A and B GelMA samples with different degrees of substitution (DS) were prepared in a controllable manner by a time-lapse loading method of methacrylic anhydride (MAA) and different feed ratios of MAA to gelatin. Type B GelMA tended to have a slightly higher DS compared to type A GelMA, especially in a lower feed ratio of MAA to gelatin. All the type A and type B GelMA solutions with different DS exhibited shear thinning behaviours at 37 °C. However, only GelMA with a high DS had an easy-to-extrude feature at room temperature. The cell-laden printed constructs of types A and B GelMA at 20% w/v showed around 75% cell viability.

Beyond the Modification Degree: Impact of Raw Material on Physicochemical Properties of Gelatin Type A and Type B Methacryloyls

“…Our results are generally in accordance with results reported by Lee et al., who also compared the DM of G A and G B methacryloyls: Their highest feed ratio of 0.1 mL MAAnh per 1 g gelatin corresponded roughly to our twofold molar excess (GM2). Like us, they observed a nearly quantitative conversion of amino groups and no difference in the DM between G A and G B derivatives at this feed ratio of MAAnh.…”

“…Nevertheless, other studies on GM derivatives from lower to similar DMs than in this study, found that the mechanical stiffness of GM hydrogels increased in direct correlation with the DM . In conclusion, we suggest that physical and chemical cross‐linking complement each other in gels that are capable of both such as GM2 and GM5, and that an optimum can be achieved in terms of elastic gel stiffness, which can be predicted to be in the range of GM2 or GelMa2.2 as introduced in ref.…”

“…However, in spite of the fact that the two different processes of hydrolysis affect the gelatin raw materials’ properties, it was not studied so far if and to what extent the used raw G A or G B material defines the properties of the prepared GMs. To the best of our knowledge, the only study addressing this point was published by Lee et al., who investigated G A M and G B M for bioink application and observed a higher DM of G B M compared to G A M and higher storage moduli of resulting hydrogels as well.…”

Rotation-assisted wet-spinning of UV-cured gelatin fibres and nonwovens

“…whereby an increase in shear rate is corelated with a decrease in shear viscosity (), in line with previous studies (49,52). When the shear rate is increased, gelatin chains disentangle since molecular interactions are attenuated, and the corresponding solution viscosity is reduced.…”

Aqueous Two‐Phase Emulsion Bioink‐Enabled 3D Bioprinting of Porous Hydrogels

“…GelMA is a temperature-sensitive material, which is more viscous at lower temperatures than at higher temperatures because of the reversible physical crosslinking. [27] Thus, the rheology of the GelMA bioinks can be readily regulated by adjusting the temperature. To examine the effect of PEO on the rheological properties of the GelMA-PEO emulsion bioinks, we examined the viscosity of different formulations of the GelMA-PEO emulsion bioinks as a function of temperature (Figure 2f).…”