Roberts Justine J, Naudiyal Pratibha, Lim Khoon S, Poole-Warren Laura A, Martens Penny J
Graduate School of Biomedical Engineering, UNSW Australia, Sydney, 2052 NSW Australia.
Christchurch Regenerative Medicine and Tissue Engineering (CReaTE) Group, Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago Christchurch, Christchurch, 8011 New Zealand.
Biomater Res. 2016 Oct 5;20:30. doi: 10.1186/s40824-016-0077-z. eCollection 2016.
Dityrosine crosslinking in proteins is a bioinspired method of forming hydrogels. This study compares oxidative enzyme initiators for their relative crosslinking efficiency and cytocompatibility using the same phenol group and the same material platform. Four common enzyme and enzyme-like oxidative initiators were probed for resulting material properties and cell viability post-encapsulation.
All four initiators can be used to form phenol-crosslinked hydrogels, however gelation rates are dependent on enzyme type, concentration, and the oxidant. Horseradish peroxidase (HRP) or hematin with hydrogen peroxide led to a more rapid poly (vinyl alcohol)-tyramine (PVA-Tyr) polymerization (10-60 min) because a high oxidant concentration was dissolved within the macromer solution at the onset of crosslinking, whereas laccase and tyrosinase require oxygen diffusion to crosslink phenol residues and therefore took longer to gel (2.5+ hours). The use of hydrogen peroxide as an oxidant reduced cell viability immediately post-encapsulation. Laccase- and tyrosinase-mediated encapsulation of cells resulted in higher cell viability immediately post-encapsulation and significantly higher cell proliferation after one week of culture.
Overall this study demonstrates that HRP/HO, hematin/HO, laccase, and tyrosinase can create injectable, phenol-crosslinked hydrogels, however oxidant type and concentration are critical parameters to assess when phenol crosslinking hydrogels for cell-based applications.
蛋白质中的二酪氨酸交联是一种受生物启发形成水凝胶的方法。本研究使用相同的酚基团和相同的材料平台，比较氧化酶引发剂的相对交联效率和细胞相容性。研究了四种常见的酶和类酶氧化引发剂在包封后的材料性能和细胞活力。
所有四种引发剂均可用于形成酚交联水凝胶，然而凝胶化速率取决于酶的类型、浓度和氧化剂。辣根过氧化物酶（HRP）或血红素与过氧化氢导致聚乙烯醇 - 酪胺（PVA-Tyr）聚合更快（10 - 60分钟），因为在交联开始时大分子溶液中溶解了高浓度的氧化剂，而漆酶和酪氨酸酶需要氧气扩散来交联酚残基，因此凝胶化时间更长（2.5小时以上）。使用过氧化氢作为氧化剂在包封后立即降低了细胞活力。漆酶和酪氨酸酶介导的细胞包封在包封后立即导致更高的细胞活力，并且在培养一周后细胞增殖显著更高。
总体而言，本研究表明HRP/H₂O₂、血红素/H₂O₂、漆酶和酪氨酸酶可以制备可注射的酚交联水凝胶，然而在为基于细胞的应用制备酚交联水凝胶时，氧化剂类型和浓度是需要评估的关键参数。
