Preparation and properties of biphasic hydrogels with tunable microstructures

Biphasic hydrogels are one of the most important biomaterials in tissue engineering due to their ability to mimic the properties of extracellular matrix. However, the lack of quantitative researches on biphasic hydrogel systems hinder the precise construction of the necessary living conditions for different cells. This fundamental study focuses on a biphasic emulsion hydrogel system consisting of polyethylene glycol diacrylate (PEGDA) and gelatin methacryloyl (GelMA), emphasizing the importance of microstructure in determining the physicochemical properties of biphasic hydrogels. Our approach utilizes a water-in-water (W/W) emulsion system, which is easy to operate and requires no purification steps. By constructing the phase diagram of PEGDA/GelMA biphasic emulsions, we demonstrate that adjusting the volume fractions of the two components results in distinct microstructures, including droplet-based and bicontinuous forms. The composition of biphasic hydrogel significantly influences its mechanical properties, swelling behavior, and biodegradability. Furthermore, the excellent biocompatibility of PEGDA/GelMA biphasic hydrogel system was demonstrated. This study conducts a more in-depth and quantitative study of the PEGDA/GelMA biphasic system. making it a versatile platform for creating precisely biomimetic environments suitable for cell encapsulation and tissue regeneration applications.