Min Jiakang, Ma Changde, Liu Xiaoguang, Li Jiaxin, Jiang Hanqing, Wen Xin, Chen Xuecheng, Mijowska Ewa, Tang Tao
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Road 5625, Changchun 130022, China.
University of Chinese Academy of Sciences, Beijing 100039, China.
ACS Omega. 2018 Dec 18;3(12):17573-17580. doi: 10.1021/acsomega.8b01587. eCollection 2018 Dec 31.
Although many biosilicification methods based on cationic linear α-poly -l- lysine for synthesis of polylysine/silica hybrids have been investigated, these methods tend to rely on the counteranions, added catalysts, and complex synthesis process. To explore a simple and efficient biosilicification method, in this work, branched poly-l-lysine (BPL) is used as both a catalyst to hydrolyze tetraethoxysilane (TEOS) and an in situ template to direct silicic acids forming polylysine/silica hybrids in one-pot mode. The catalysis of BPL to hydrolyze TEOS results from the abundant hydrogen bonding (as the active site) to increase the nucleophilicity of BPL. Meanwhile, the hydrogen bonding is also found to be the key factor determining the self-assembly of BPL. During biosilicification, owing to self-assembly of BPL molecules, BPL would form spherical particles by keeping a random-coil conformation or form lamellar structures by undergoing a conformational transition from a random-coil to β-sheet construction. As a result, polylysine/silica hybrids with tunable topological structures are synthesized using aggregated BPLs as templates after the hydrolysis of TEOS. This finding of applying BPL to fulfill the biosilicification procedure without counteranions and added catalysts would enable a better understanding of the polypeptide-governed biosilicification process and pave a way for fabricating complex inorganic architectures applicable to silica transformational chemistry.
尽管已经研究了许多基于阳离子线性α-聚-L-赖氨酸合成聚赖氨酸/二氧化硅杂化物的生物矿化方法，但这些方法往往依赖于抗衡阴离子、添加的催化剂以及复杂的合成过程。为了探索一种简单高效的生物矿化方法，在本工作中，支链聚-L-赖氨酸（BPL）既用作水解四乙氧基硅烷（TEOS）的催化剂，又用作原位模板，以一锅法直接引导硅酸形成聚赖氨酸/二氧化硅杂化物。BPL对TEOS水解的催化作用源于丰富的氢键（作为活性位点），从而增加了BPL的亲核性。同时，氢键也被发现是决定BPL自组装的关键因素。在生物矿化过程中，由于BPL分子的自组装，BPL会通过保持无规卷曲构象形成球形颗粒，或者通过从无规卷曲到β-折叠结构的构象转变形成层状结构。结果，在TEOS水解后，以聚集的BPL为模板合成了具有可调拓扑结构的聚赖氨酸/二氧化硅杂化物。这一应用BPL在无抗衡阴离子和添加催化剂的情况下完成生物矿化过程的发现，将有助于更好地理解多肽控制的生物矿化过程，并为制造适用于二氧化硅转化化学的复杂无机结构铺平道路。
