326: Building active biomolecular fields for guiding self-assembly

Abstract: Biological development shows how reaction–diffusion processes organize matter on micron-to-millimeter scales. Biomolecular reactions generate concentration fields that act as spatial cues—for example, patterning the fly compound eye, guiding neural wiring, and structuring microbial communities. Since Turing’s foundational work in the 1950s, reaction–diffusion has been studied extensively, yet we still lack clear design principles for how developmental-scale patterns can reliably arise from chemical networks. We also lack general methods for harnessing these processes to drive and control materials. Here I present a structured approach for designing biochemical reaction–diffusion systems based on localized sources (“monopoles”) that emit signals which are degraded throughout the vessel, producing concentration fields with well-defined size and structure. These fields can be made insensitive to container size and shape, and their geometry can be programmed by reaction kinetics rather than boundary conditions. Because the system operates at a non-equilibrium steady state, the resulting biomolecular fields act as stable energy sources that can perform work. I will show examples in which such fields direct materials assembly. Field-directed strategies enable complex, spatially heterogeneous compositions that are difficult or impossible to produce using traditional fabrication methods, and may open routes to materials with new optical, mechanical, and transport properties.