Quantitative prediction of the phase diagram of DNA-functionalized nano-colloids

TL;DR

This paper introduces a computationally efficient, experimentally parameterized model to predict the phase behavior of DNA-functionalized nano-colloids, highlighting the importance of non-pairwise interactions and aligning well with experimental data.

Contribution

The authors develop a coarse-grained, experimentally grounded model that accurately predicts colloidal phase behavior without assuming pairwise additivity.

Findings

The model predicts the correct solid phase structure.

It provides accurate melting temperature estimates.

Pairwise additivity assumptions lead to significant errors.

Abstract

We present a coarse-grained model of DNA-functionalized colloids that is computationally tractable. Importantly, the model parameters are solely based on experimental data. Using this highly simplified model, we can predict the phase behavior of DNA-functionalized nano-colloids without assuming pairwise additivity of the inter-colloidal interactions. Our simulations show that for nano-colloids, the assumption of pairwise additivity leads to substantial errors in the estimate of the free energy of the crystal phase. We compare our results with available experimental data and find that the simulations predict the correct structure of the solid phase and yield a very good estimate of the melting temperature. Current experimental estimates for the contour length and persistence length of single-stranded DNA sequences are subject to relatively large uncertainties. Using the best available estimates, we obtain predictions for the crystal lattice constants that are off by a few percent: this indicates that more accurate experimental data on ssDNA are needed to exploit the full power of our coarse-grained approach.