B12-dependent photoresponsive protein hydrogels for controlled stem cell/protein release

• Published in: Proceedings of the National Academy of Sciences - PNAS 2017-06, Vol.114 (23), p.5912-5917
• Main Authors: Wang, Ri, Yang, Zhongguang, Luo, Jiren, Hsing, I-Ming, Sun, Fei
• Format: Article
• Language: English
• Subjects: Biological Sciences; Physical Sciences
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1621350114

Thanks to the precise control over their structural and functional properties, genetically engineered protein-based hydrogels have emerged as a promising candidate for biomedical applications. Given the growing demand for creating stimuli-responsive “smart” hydrogels, here we show the synthesis of entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. The resulting hydrogel composed of physically self-assembled CarHC polymers exhibited a rapid gel-sol transition on light exposure, which enabled the facile release/recovery of 3T3 fibroblasts and human mesenchymal stem cells (hMSCs) from 3D cultures while maintaining their viability. A covalently cross-linked CarHC hydrogel was also designed to encapsulate and release bulky globular proteins, such as mCherry, in a light-dependent manner. The direct assembly of stimuli-responsive proteins into hydrogels represents a versatile strategy for designing dynamically tunable materials.