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Trace Solvent as a Predominant Factor To Tune Dipeptide Self-Assembly

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journal contribution
posted on 12.01.2016, 00:00 by Juan Wang, Kai Liu, Linyin Yan, Anhe Wang, Shuo Bai, Xuehai Yan
Solvent molecules such as water are of key importance for tuning self-assembly in biological systems. However, it remains a great challenge to detect the role of different types of noncovalent interactions between trace solvents and biomolecules such as peptides. In this work, we discover a dominant role of trace amounts of solvents for mediation of dipeptide self-assembly, in which solvent-bridged hydrogen bonding is demonstrated as a crucial force in directing fiber formation. Hydrogen-bond-forming solvents (including ethanol, N,N-dimethylformamide, and acetone) can affect the hydrogen bonding of CO and N–H in diphenylalanine (FF) molecules with themselves, but this does not induce π–π stacking between FF molecules. The directional hydrogen bonding promotes a long-range-ordered arrangement of FF molecules, preferentially along one dimension to form nanofibers or nanobelts. Furthermore, we demonstrate that water with strong hydrogen-bond-forming capability can notably speed up structure formation with long-range order, revealing the importance of water as a trace solvent for regulation of persistent and robust fiber formation.