Controlling supramolecular assembly remains a major challenge for materials science and synthetic biology. Biopolymers organize into multimolecular architectures via two‐step nucleation processes involving dynamic intermediate solute‐rich phases. Here we present spectroscopic analyses of metastable phases formed with a congener of the Alzheimer's disease Aβ peptide that reveals diverse populations of single β‐sheets. The degree of order in this liquid‐like particle phase is remarkable both in the range of sheets and the selection of a single propagating nucleus. The resulting fibril seed is less stable in solution and cooperatively transforms into another fibril. The conformational dynamics of this peptide provide a mechanistic model for controlling the range of polymorphic amyloid assemblies in health and disease.

Living systems contain remarkable functional capability built within sophisticated self-organizing frameworks. Defining the assembly codes that coordinate these systems could greatly extend nanobiotechnology. To that end, we have highlighted the self-assembling architecture of the chlorosome antenna arrays and report the emulation and extension of their features for the development of cell-compatible photoredox materials. We specifically review work on amyloid peptide scaffolds able to (1) organize light-harvesting chromophores, (2) break peptide bilayer symmetry for directional energy and electron transfer, and (3) incorporate redox active metal ions at high density for energy storage.

Melanosomes have the capacity to bind significant concentrations of calcium, suggesting there are surface binding sites that enable cations to access the interior of fully pigmented melanosomes. The surface of melanosomes is known to contain significant concentrations of carboxylate groups which likely are the initial biding sites for calcium, but their arrangement on the surface of the melanosome is not known. In various calcium proteins, a bidentate coordination by two carboxylate groups is the most common structure. In this study, we determine the distance between neighboring surface carboxylic acid groups by examining the binding of a series of diamines (+)H3N(CH2)mNH3(+) (m = 1-5) to melanosomes isolated from the ink sacs of Sepia officinalis and bovine choroid tissue. Of these amines, ethylenediamine (m = 2) shows optimal bidentate binding, revealing a narrow distribution of distances between neighboring carboxylic acid groups, ∼480 pm, similar to that found in proteins for calcium binding motifs involving two carboxylate groups.

What are the main challenges in the broad area of your research? Processing of polymeric materials has been exploited widely for new material development. In aqueous environments, biopolymers undergo liquid-liquid phase separation, creating dynamic solute-rich particle phases where further processing occurs. Here we define the population of molecular assemblies that cooperatively seed the nucleation of higher order assembly. While nucleation predictions in solution remain challenging, these multiple limited-volume particle phases enable integrated spectroscopic analysis of cooperative transitions. Our analyses with peptides define a subset of assemblies pre-ordered for nucleation and reveal a pathway for templating paracrystalline assembly. This insight can now be extended to the nucleation and assembly of other polymeric materials. Does the research open other avenues that you would like to investigate? We are now exploring external templates (e.g. metals, nucleic acids, and covalent tagging strategies) that intercept these nascent structural assemblies and direct supramolecular assem

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