Hydrogels are 3D polymers that can swell and absorb many times their weight in water. They serve as the main component of bioinks, and provide the necessary environment for cells to thrive. Hydrogels used for bioprinting are meant to mimic the natural extracellular environment that is found in living tissues so that encapsulated cells can grow as they would in vivo. Their physical characteristics are largely determined by their chemical make-up, which either occurs naturally or is created synthetically. Their porous nature and tissue-like elastic properties make it possible for cells to grow easily, receive nutrients, and proliferate as they would in the body.
In addition to their ability to support cell growth, hydrogels can be used in many other biotechnological applications because of their tunable characteristics. The physical properties of hydrogels can easily be changed depending on the materials used when the hydrogel is made, the conditions under which it is crosslinked, and the addition of supplemental materials. For example, the controlled variation of chemically-added groups allows hydrogels to possess unique patterns, structures, and phenotypes, creating an ideal platform to control cellular behaviours and engineer tissues.
GelMA is a popular hydrogel used in microfabrication research because it possesses many advantages that lead to successful experiments. GelMA is a semi-synthetic hydrogel, meaning it has both natural and synthetic elements. The natural component of GelMA is the gelatin backbone of the hydrogel. Gelatin is the product formed when collagen, a commonly occurring protein in all mammals, is hydrolyzed. During hydrolyzation, water reacts with collagen in a manner that splits the large protein into various smaller products, including gelatin. The complex structure of collagen is denatured during this reaction, which removes inconsistencies in the protein’s structure. The leftover gelatin has a much more uniform structure, a crucial factor in GelMA’s success as a hydrogel. Gelatin’s uniform structure will allow for consistent addition of cross-linking substituents, increased biocompatibility, and decreased antigenicity when compared to collagen. These characteristics make GelMA a more suitable hydrogel choice for tissue engineering as opposed to collagen.
GelMA is formed when the gelatin backbone is reacted with methacryloyl (MA) substituent groups. The MA substitutes are what gives GelMA its structural integrity and physical characteristics. These can easily be controlled by varying the degree to which gelatin is substituted with MA. However, MA is a cytotoxic substance and can be detrimental to cells if not fully reacted or removed from the reaction. Once the required degree of substitution has been achieved, the reaction must be stopped and the GelMA must be cleared of any unreacted MA.
Additionally, water-soluble photoinitiators are added to GelMA once the substitution is complete to initiate cross-linking of the GelMA macromers. When exposed to certain wavelengths of light, the photoinitiators will become excited and stimulate the MA groups attached to the gelatin backbone to bond together, creating strong connections and stiffening GelMA. The crosslinks formed during light exposure solidify the structure and allow it to withstand the applied forces, giving GelMA its structural integrity. By controlling which areas of GelMA are exposed to light, unique patterns can be formed.
GelMA is one of the most popular choices for bioprinting research for good reason. Its versatility across many applications makes it a master-of-all-trades bioink. If you are using GelMA for your research then consider The GelMA Company for your GelMA needs. Our GelMA is pure, sterile, and customizable to fit even the most specific needs.