Self assembling cluster crystals from DNA based dendritic nanostructures

Abstract

Cluster crystals are periodic structures with lattice sites occupied by several, overlapping building blocks, featuring fluctuating site occupancy, whose expectation value depends on thermodynamic conditions. Their assembly from atomic or mesoscopic units is long-sought-after, but its experimental realization still remains elusive. Here, we show the existence of well-controlled soft matter cluster crystals. We fabricate dendritic-linear-dendritic triblock composed of a thermosensitive water-soluble polymer and nanometer-scale all-DNA dendrons of the first and second generation. Conclusive small-angle X-ray scattering (SAXS) evidence reveals that solutions of these triblock at sufficiently high concentrations undergo a reversible phase transition from a cluster fluid to a body-centered cubic (BCC) cluster crystal with density-independent lattice spacing, through alteration of temperature. Moreover, a rich concentration-temperature phase diagram demonstrates the emergence of various ordered nanostructures, including BCC cluster crystals, birefringent cluster crystals, as well as hexagonal phases and cluster glass-like kinetically arrested states at high densities.

The growth rate of DNA condensate droplets increases with the size of participating subunits

“…We expect that our results will accelerate the design of synthetic biomolecular condensates, in particular custom DNA and RNA liquids, as well as expand the toolkit of composite materials that DNA take advantage of star-shaped subunits 27,28 , which are relevant for materials science, synthetic biology and biotechnology applications.…”

Phase Field Crystal model for particles with n-fold rotational symmetry in two dimensions

“…The particles that we have in mind in this work do not possess a hard core. Therefore, the phases described here correspond to cluster crystals similar as in [10,[33][34][35][36][37]. In contrast, in many particulate systems a hard core prevents large overlaps of particles.…”

Continuum mechanics for the elastic properties of crystals: Microscopic approach based on projection-operator formalism

“…Theoretical and simulation studies in reference [14] show how theoretical frameworks derived in references [10,11] can be successfully implemented to obtain quantitative insights regarding mechanical response of solids. Though the previous studies [11,14] were restricted to reversible mechanical response in isothermal crystals, the theories success in predicting elastic properties of a model known to mimic crystalline phases in DNA-based dendritic nanostructures [13], illustrates the scope of applicability of this formulation.…”

“…These general theoretical frameworks were first implemented to a specific model of cluster crystals by Häring et al [11]. Cluster crystals are defect-rich crystals, where an inhomogeneously distributed number of soft particles occupies lattice sites [12,13]. An extensive examination of the elastic properties of the same cluster crystals, taken up by Ganguly et al [14], infers how local disorder quantitatively impacts mechanical response.…”