From colloidomer chains, through foldamer nets, to the assembly of icoahedral shells

Self-assembly is an effectice way of building icosahedral shells for the encapsulation and release of active ingredients, akin to viral capsids. Experimentally, they have been assembled on the nanoscale using DNA origami with complex shapes and interactions [1], while numerical simulations have shown that patchy particles [2], or planar nets [3] with distinct directional bonds can also achieve their high yield. Here we show that a simpler system of two types of sticky isotropic particles is sufficient to self-assemble icosahedral shells if the particle-particle bonds can freely rearrange, as in the case of DNA-functionalized emulsion droplets. Previously, we showed that alternating (ABAB...) colloidomer chains of droplets efficiently fold into unique 2D structures we call foldamers according to specific temperature protocols [4]. We now enumerate and find over 80,000 design strategies that result in the supracolloidal asembly of pairs of small foldamers (with sizes 6+6, 7+5, and 8+4) into planar 12-particle nets capable of further folding into icosahedra. From this set, we use MD simulations to select the foldamer pairs with the highest yield and study their wrapping around a seed particle into icosahedra, which we then test experimentally. Finding such designable self-assembling systems offers a promising route to functional materials capable of targeted drug delivery.

[1] Christian Sigl, Elena M. Willner, Michael F. Hagan, Seth Fraden, Hendrik Dietz, & et al. (2021). Nature Materials 20, 1281–1289.

[2] Diogo E. P. Pinto, Petr Šulc, & John Russo (2023). Design strategies for the self-assembly of polyhedral shells. Proceedings of National Academy of Sciences, 120 (16) e2219458120

[3] Paul M. Dodd, Pablo F. Damasceno, & Sharon C. Glotzer (2018). Universal folding pathways of polyhedron nets. Proceedings of National Academy of Sciences, 115 (29) E6690-E6696.

[4] Angus McMullen, Maitane Muñoz Basagoiti, Zorana Zeravcic & Jasna Brujic (2022). Self-assembly of emulsion droplets through programmable folding. Nature, 610 (7932), 502-506.