No abstract

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.

Photocatalytically active, multi-chambered, biomolecule-based microspheres were prepared by hierarchical co-assembly of simple dipeptides and porphyrins. The colloidal microspheres are highly hydrated and consist of a network of J-aggregate nanoscale substructures that serve as light-harvesting antennae with a relatively broad spectral cross-section and considerable photostability. These optical properties can be exploited in photocatalytic reactions involving inorganic or organic species. Taken together, these structural and functional features suggest that soft porous biomolecule-based colloids are a plausible photosynthetic model that could be developed towards demonstrating aspects of primitive abiotic cellularity.