It is 50 years since the publication of Nobel Laureate Philip Anderson’s famous essay More is different in which he argues that new phenomena emerge with increasing layers of complexity. For example, cells can grow and move, but they are constructed from molecules, proteins, lipids and polymers that are ‘just chemistry’. There is active interdisciplinary research into how complex structures with enhanced functionality can be assembled from simple building blocks, both to understand emergent biological processes but also to fabricate self-assembling structures with technological applications.
In a recent paper, DPhil student Joakim Bohlin with Professors Ard Louis, Andrew Turberfield and Oxford Rudolf Peierls Centre for Theoretical Physics alumnus Petr Sulc, present a new algorithm which optimises the search for solutions to the inverse design problem: how to design the optimum building blocks that will most efficiently self-assemble into a given target structure.
The design space for self-assembled multicomponent objects ranges from a solution in which every building block is unique to one with the minimum number of distinct building blocks that unambiguously define the target structure. Using a novel pipeline, the group explored the design spaces for a set of structures of various sizes and complexities. To understand the implications of the different solutions, the group analysed their assembly dynamics using patchy particle simulations; they studied the influence of the number of distinct building blocks and the angular and spatial tolerances on their interactions on the kinetics and yield of the target assembly.
The work shows that the resource-saving solution with minimum number of distinct blocks can often assemble just as well (or faster) than designs where each building block is unique. The group further used their methods to design multifarious structures, where building blocks are shared between different target structures, as well as using coarse-grained DNA simulations to investigate the realisation of multicomponent shapes using DNA nanostructures as building blocks.
The results are relevant to the self-assembly of DNA origami or patchy colloids with applications that include meta-materials for optical sensing and computing, 3D electronic circuit manufacture, and molecular factory construction. They may also help explain why self-assembling structures in nature are more likely to be symmetric.