Highly water-soluble, pH sensitive and biocompatible PAMAM `dendrizyme' to maintain catalytic activity in complex medium
Highly water-soluble, pH sensitive and biocompatible PAMAM `dendrizyme' to maintain catalytic activity in complex medium
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高度水溶性、pH 敏感性和生物相容性 PAMAM“树状酶”，可在复杂介质中保持催化活性
DOI：
10.1016/j.msec.2017.02.144
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Zhang Xuwu
中科院分区：
文献类型：
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作者：
Wang Longgang;Cui Yanshuai;Chen Shengfu;Wang Guangzhi;Gao Dawei;Liu Yanping;Luo Qiaoyue;Liu Zhiwei;Zhang Xuwu
基于树枝状大分子的合成模拟酶已引起人们的极大关注。然而，这种模拟酶不同于天然酶，它对pH敏感，具有生物相容性，并在生物复杂介质中保持其催化活性。由伯胺和羧基组成的单一两性离子层可能是获得这些性质的有用方法。在此，我们报道了一种新的简便的制备模拟酶的方法。用顺丁烯二酸酐和半胱胺对5代聚氨基胺树枝状大分子(G5PAMAM)与游离氯化高铁血红素(G5Hs)的络合物进行了修饰。结果表明，模拟酶(G5HMCs)在pH为4~9的范围内具有较高的pH敏感性和良好的稳定性，而在pH为5的条件下，两天后可观察到明显的游离氯化高铁血红素沉淀。G5HMC(3：1)在等电点具有最佳催化活性。此外，G5HMCs具有良好的生物相容性。与纤维蛋白原孵育的G5HMCs在24小时内稳定，而G5Hs立即形成大的聚集体。G5HMC(3：12 mg/mL)对HeLa细胞和A549细胞作用24 h几乎没有细胞毒性，而G5H(3：1)对HeLa细胞和A549细胞有严重的细胞毒性，细胞形态观察也证实了这一点。与磷酸盐缓冲盐水(PBS)溶液相比，G5HMCs在牛血清白蛋白(BSA)溶液中的催化活性完全保持不变，而在BSA溶液中，氯化高铁血红素的催化活性下降到73.5-81.5%，这是由于G5HMCs与BSA的相互作用比游离氯化血红素少所致。本报告中描述的表面功能化方案将代表一种通用的方法来制备用于生物医学相关应用的水溶性、pH敏感、生物相容性和高效的人工酶。
The dendrimer based synthetic mimetic enzyme has been drawing great attention. However, this mimetic enzyme is different from the natural enzymes, which are pH sensitive, biocompatible and keep their catalytic activity in biological complex medium. A single zwitterionic layer composed by primary amine and carboxyl groups may be a useful method to obtain these properties. Herein, we report a novel facile method to prepare a mimetic enzyme. The complexes of generation 5 poly(amido amine) dendrimers (G5 PAMAM) with free hemin (G5Hs) were modified by the maleic anhydride and cysteamine. Results showed that the mimetic enzymes (G5HMCs) had pH sensitivity and good stability by varying the pH from 4 to 9, while significant precipitation was observed for free hemin at pH 5 after two days. The G5HMC (3:1) showed optimal catalytic activity at its isoelectric point. Furthermore, G5HMCs displayed excellent biocompatibility. The G5HMCs incubated with fibrinogen were stable for 24 h, while G5Hs immediately formed large aggregates. G5HMC (3:1 2 mg/mL) displayed little cytotoxicity with HeLa cells or A549 cells for 24 h, while G5H (3:1) had serious cytotoxicity, which was also demonstrated by cell morphology observation. At last, G5HMCs fully preserved their catalytic activity in bovine serum albumin (BSA) solution compared with phosphate buffer saline (PBS) solution, while hemin decreased to 73.5–81.5% catalytic activity in BSA solution, which was caused by the less interaction with BSA for G5HMCs than free hemin. The surface functionalization schemes described in this report would represent a versatile method to prepare water-soluble, pH sensitive, biocompatible, and efficient artificial enzymes for biomedical related applications.