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All-aqueous emulsions exploit spontaneous liquid-liquid separation and due to their water-based nature are particular advantageous for the biocompatible storage and processing of biomacromolecules. However, the ultralow interfacial tensions characteristic of all-aqueous interfaces represent an inherent limitation to the use of thermally adsorbed particles to achieve emulsion stability. Here, we use protein nanofibrils to generate colloidosome-like two-dimensional crosslinked networks of nanostructures templated by all-aqueous emulsions, which we term fibrillosomes. We show that this approach not only allows us to operate below the thermal limit at ultra-low surface tensions but also yields structures that are stable even in the complete absence of an interface. Moreover, we show that the growth and multilayer deposition of fibrils allows us to control the thickness of the capsule shells. These results open up the possibility of stabilizing aqueous two-phase systems using natural proteins, and creating self-standing protein capsules without the requirement for three-phase emulsions or water/oil interfaces.

It is increasingly recognized that molecular chaperones play a key role in modulating the formation of amyloid fibrils, a process associated with a wide range of human disorders. Understanding the detailed mechanisms by which they perform this function, however, has been challenging because of the great complexity of the protein aggregation process itself. In this work, we build on a previous kinetic approach and develop a model that considers pairwise interactions between molecular chaperones and different protein species to identify the protein components targeted by the chaperones and the corresponding microscopic reaction steps that are inhibited. We show that these interactions conserve the topology of the unperturbed reaction network but modify the connectivity weights between the different microscopic steps. Moreover, by analysing several protein-molecular chaperone systems, we reveal the striking diversity in the microscopic mechanisms by which molecular chaperones act to suppress amyloid formation.

Protein aggregation plays a key role in neurodegenerative disease, giving rise to small oligomers that may become cytotoxic to cells. The fundamental microscopic reactions taking place during aggregation, and their rate constants, have been difficult to determine due to lack of suitable methods to identify and follow the low concentration of oligomers over time. Here we use single-molecule fluorescence to study the aggregation of the repeat domain of tau (K18), and two mutant forms linked with familial frontotemporal dementia, the deletion mutant ΔK280 and the point mutant P301L. Our kinetic analysis reveals that aggregation proceeds via monomeric assembly into small oligomers, and a subsequent slow structural conversion step before fibril formation. Using this approach, we have been able to quantitatively determine how these mutations alter the aggregation energy landscape.

The self-assembly of molecular building blocks into nano- and micro-scale supramolecular architectures has opened up new frontiers in polymer science. Such supramolecular species not only possess a rich set of dynamic features as a consequence of the non-covalent nature of their core interactions, but also afford unique structural characteristics. Although much is now known about the manner in which such structures adopt their morphologies and size distributions in response to external stimuli, the kinetic and thermodynamic driving forces that lead to their transformation from soluble monomeric species into ordered supramolecular entities have remained elusive. Here we focus on Boc-diphenylalanine, an archetypical example of a peptide with a high propensity towards supramolecular self-organization, and describe the pathway through which it forms a range of nano-assemblies with different structural characteristics. Our results reveal that the nucleation process is multi-step in nature and proceeds by Ostwald's step rule through which coalescence of soluble monomers leads to the formation of nanospheres, which then undergo ripening and structural conversions to form the final supramolecular assemblies. We characterize the structures and thermodynamics of the different phases involved in this process and reveal the intricate nature of the transitions that can occur between discrete structural states of this class of supramolecular polymers.