文献类型：期刊文献

英文题名：Effects of Secondary Structures and pH on the Self-Assembly of Poly(ethylene glycol)-b-polytyrosine

作者：Jiang, Caixia[1];Zhao, Chonghao[1];Xu, Peng[1];Song, Qipeng[1];Tao, Xinfeng[1];Lin, Shaoliang[1]

机构：[1]East China Univ Sci & Technol, Minist Educ, Sch Mat Sci & Engn, Key Lab Ultrafine Mat,Shanghai Key Lab Adv Polyme, Shanghai 200237, Peoples R China

年份：2024

卷号：25

期号：8

起止页码：5028

外文期刊名：BIOMACROMOLECULES

收录：;EI(收录号：20242716619572);WOS:【SCI-EXPANDED(收录号:WOS:001261320300001)】；

基金：This work was supported by the National Natural Science Foundation of China (52325308, 21901073, and 52073092).

语种：英文

外文关键词：Alkalinity - Amino acids - Block copolymers - Controlled drug delivery - Ethylene glycol - Polyethylene oxides - Polyols - Ring opening polymerization - Self assembly

摘要：Different from conventional synthetic polymers, polypeptides exhibit a distinguishing characteristic of adopting specific secondary structures, including random coils, alpha-helixes, and beta-sheets. The conformation determines the rigidity and solubility of polypeptide chains, which further direct the self-assembly and morphology of the nanostructures. We studied the effect of distinct secondary structures on the self-assembly behavior of polytyrosine (PTyr)-derived amphiphilic copolymers. Two block copolymers of enantiopure poly(ethylene glycol)-b-poly(l-tyrosine) (PEG-b-P(l-Tyr)) and racemic poly(ethylene glycol)-b-poly(dl-tyrosine) (PEG-b-P(dl-Tyr)) were synthesized through the ring-opening polymerization of l-tyrosine N-thiocarboxyanhydride (l-Tyr-NTA) and dl-tyrosine N-thiocarboxyanhydride (dl-Tyr-NTA), respectively, by using poly(ethylene glycol) amine as the initiator. PEG(44)-b-P(l-Tyr)(10) adopts a beta-sheet conformation and self-assembles into rectangular nanosheets in aqueous solutions, while PEG(44)-b-P(dl-Tyr)(9) is primarily in a random coil conformation with a tiny content of beta-sheet structures, which self-assembles into sheaf-like nanofibrils. A pH increase results in the ionization of phenolic hydroxyl groups, which decreases the beta-sheet content and increases the random coil content of the PTyr segments. Accordingly, PEG(44)-b-P(l-Tyr)(10) and PEG(44)-b-P(dl-Tyr)(9) self-assemble to form slender nanobelts and twisted nanoribbons, respectively, in alkaline aqueous solutions. The secondary structure-driven self-assembly of PTyr-derived copolymers is promising to construct filamentous nanostructures, which have potential for applications in controlled drug release.