Polyethylene glycol-gelatin hydrogels with tuneable stiffness prepared by horseradish peroxidase-activated tetrazine-norbornene ligation
Polyethylene glycol-gelatin hydrogels with tuneable stiffness prepared by horseradish peroxidase-activated tetrazine-norbornene ligation
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DOI：
10.1039/c7tb02764h
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发表时间：
2018-03-07
影响因子：
7
通讯作者：
Truong, V. X.
中科院分区：
文献类型：
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作者：
Carthew, J.;Frith, J. E.;Truong, V. X.
四嗪-异戊烯连接先前已应用于生物正交聚合物交联以形成适合于3D细胞培养的水凝胶。然而，四嗪基团在生物环境中易于被游离硫醇还原，从而降低交联效率并缩短含四嗪接头的储存。在这里，我们介绍了一种方法，形成一个四嗪基团原位催化氧化的二氢四嗪，辣根过氧化物酶（HRP）。酶促氧化在低HRP浓度下是高效的，并且不需要过氧化氢，从而当HRP被添加到4臂PEG二氢四嗪和明胶双烯的水溶液中时允许快速凝胶化。所得凝胶的储能模量可以通过改变交联剂的浓度而变化，其在1.2- 3.8kPa的范围内。包封在这些凝胶中的具有不同刚度的人间充质干细胞显示出不同的相互作用和形态，并且可以维持至少32天的3D培养的延长的培养期。因此，四嗪-三烯的酶促活化是对四嗪连接的有吸引力的补充，其非常适合于组织工程中的细胞相关研究。
Tetrazine-norbornene ligation has previously been applied in bioorthognal polymer crosslinking to form hydrogels suitable for 3D cell culture. However, the tetrazine group is prone to reduction by the free thiol in a biological environment, reducing the crosslinking efficiency and shortening the storage of tetrazine containing linkers. Here, we introduce a method to form a tetrazine group in situ by catalytic oxidation of the dihydrogen tetrazine using horse radish peroxidase (HRP). Enzymatic oxidation is highly efficient at a low HRP concentration and does not require hydrogen peroxide, allowing for rapid gelation when HRP was added to an aqueous solution of 4-arm PEG dihydrogentetrazine and gelatin norbornene. The storage modulus of the resultant gels can be varied by changing the concentration of the crosslinker, which is in the range of 1.2-3.8 kPa. Human mesenchymal stem cells encapsulated within these gels, with varying stiffness, display varied interactions and morphologies and can be maintained with prolonged culture periods of at least 32 days of 3D culture. The enzymatic activation of tetrazine-norbornene is therefore an attractive addition to the tetrazine ligation that is highly suitable for cell related studies in tissue engineering.