By means of two supramolecular systems - peptide amphiphiles engaged in hydrogen-bonded β-sheets, and chromophore amphiphiles driven to assemble by π-orbital overlaps - we show that the minima in the energy landscapes of supramolecular systems are defined by electrostatic repulsion and the ability of the dominant attractive forces to trap molecules in thermodynamically unfavourable configurations. These competing interactions can be selectively switched on and off, with the order of doing so determining the position of the final product in the energy landscape. Within the same energy landscape, the peptide-amphiphile system forms a thermodynamically favoured product characterized by long bundled fibres that promote biological cell adhesion and survival, and a metastable product characterized by short monodisperse fibres that interfere with adhesion and can lead to cell death. Our findings suggest that, in supramolecular systems, function and energy landscape are linked, superseding the more traditional connection between molecular design and function.

Covalent and supramolecular polymers are two distinct forms of soft matter, composed of long chains of covalently and noncovalently linked structural units, respectively. We report a hybrid system formed by simultaneous covalent and supramolecular polymerizations of monomers. The process yields cylindrical fibers of uniform diameter that contain covalent and supramolecular compartments, a morphology not observed when the two polymers are formed independently. The covalent polymer has a rigid aromatic imine backbone with helicoidal conformation, and its alkylated peptide side chains are structurally identical to the monomer molecules of supramolecular polymers. In the hybrid system, covalent chains grow to higher average molar mass relative to chains formed via the same polymerization in the absence of a supramolecular compartment. The supramolecular compartments can be reversibly removed and re-formed to reconstitute the hybrid structure, suggesting soft materials with novel delivery or repair functions.

Silver nanoparticles have been of great interest as plasmonic substrates for sensing and imaging, catalysts, or antimicrobial systems. Their physical properties are strongly dependent on parameters that remain challenging to control such as size, chemical composition, and spatial distribution. We report here on supramolecular assemblies of a novel peptide amphiphile containing aldehyde functionality in order to reduce silver ions and subsequently nucleate silver metal nanoparticles in water. This system spontaneously generates monodisperse silver particles at fairly regular distances along the length of the filamentous organic assemblies. The metal–organic hybrid structures exhibited antimicrobial activity and significantly less toxicity toward eukaryotic cells. Metallized organic nanofibers of the type described here offer the possibility to create hydrogels, which integrate the useful functions of silver nanoparticles with controllable metallic content.

We report the construction of DNA nanotubes covalently functionalized with the cell adhesion peptide RGDS as a bioactive substrate for neural stem cell differentiation. Alteration of the Watson–Crick base pairing program that builds the nanostructures allowed us to probe independently the effect of nanotube architecture and peptide bioactivity on stem cell differentiation. We found that both factors instruct synergistically the preferential differentiation of the cells into neurons rather than astrocytes.

Targeting of vascular intervention by systemically delivered supramolecular nanofibers after balloon angioplasty is described. Tracking of self-assembling peptide amphiphiles using fluorescence shows selective binding to the site of vascular intervention. Cylindrical nanostructures are observed to target the site of arterial injury, while spherical nanostructures with an equivalent diameter display no binding.