The self assembly of peptide hydrogelators that carry aromatic substituents can be modeled by a novel nanocylindrical architecture. The proposed model suggests that the nanocylinders are formed by anti-parallel β-sheets interlocked by the π-stacking interactions of fluorenyl groups and phenyl rings. This explanation is consistent with the structures observed in TEM and the data obtained by a variety of spectroscopic techniques.

Fmoc-diphenylalanine self assembles to a hydrogel via a novel architecture based on π–π interlocked β-sheets

Self-assembled peptide-based hydrogels as scaffolds for anchorage-dependent cells

The production of functional molecular architectures through self-assembly is commonplace in biology, but despite advances1, 2, 3, it is still a major challenge to achieve similar complexity in the laboratory. Self-assembled structures that are reproducible and virtually defect free are of interest for applications in three-dimensional cell culture4, 5, templating6, biosensing7 and supramolecular electronics8. Here, we report the use of reversible enzyme-catalysed reactions to drive self-assembly. In this approach, the self-assembly of aromatic short peptide derivatives9, 10 provides a driving force that enables a protease enzyme to produce building blocks in a reversible and spatially confined manner. We demonstrate that this system combines three features: (i) self-correction—fully reversible self-assembly under thermodynamic control; (ii) component-selection—the ability to amplify the most stable molecular self-assembly structures in dynamic combinatorial libraries11, 12, 13; and (iii) spatiotemporal confinement of nucleation and structure growth. Enzyme-assisted self-assembly therefore provides control in bottom-up fabrication of nanomaterials that could ultimately lead to functional nanostructures with enhanced complexities and fewer defects.

Enzyme-assisted self-assembly under thermodynamic control.

A Dibenzofuran-Based Host Material for Blue Electrophosphorescence

Antimicrobial hydrogels are prepared based on the co-assembly of commercial Fmoc-phenylalanine and Fmoc-leucine, which act as the hydrogelator and antimicrobial building block, respectively. This co-assembled antimicrobial hydrogel is demonstrated to exhibit selective bactericidal activity for gram-positive bacteria while being biocompatible with normal mammalian cells, showing great potential as an antimicrobial coating for clinical anti-infective applications.

Gram-positive antimicrobial activity of amino acid-based hydrogels

Excimer model for fluorene and dibenzofuran

Excimer emission from dibenzofuran and substituted fluorenes

The clean photoreduction in propan-2-ol of decafluorobenzophenone to decafluorobenzhydrol and the ease of g.l.c. determination of the extent of conversion suggest this system as a new actinometer.

Jack P. Pinion

Papers

Excimer model for fluorene and dibenzofuran

Excimer emission from dibenzofuran and substituted fluorenes

A new actinometer: decafluorobenzophenone–isopropyl alcohol