Switch-like surface binding of competing multivalent particles

N.B Tito,D Frenkel

doi:10.1140/epjst/e2016-60119-6

N.B Tito, D Frenkel

Open Access

https://doi.org/10.1140/epjst/e2016-60119-6

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Abstract

Multivalent particles competing for binding on the same surface can exhibit switch-like behaviour, depending on the concentration of receptors on the surface. When the receptor concentration is low, energy dominates the free energy of binding, and particles having a small number of strongly-binding ligands preferentially bind to the surface. At higher receptor concentrations, multivalent effects become significant, and entropy dominates the binding free energy; particles having many weakly-binding ligands preferentially bind to the surface. Between these two regimes there is a “switch-point”, at which the surface binds the two species of particles equally strongly. We demonstrate that a simple theory can account for this switch-like behaviour and present numerical calculations that support the theoretical predictions. We argue that binding selectivity based on receptor density, rather than identity, may have practical applications.

Highlights

Systems comprising many different chemical ingredients may exhibit complex physical behaviour that is absent in systems with fewer components
A non-biological example is the self-assembly of an elaborate structure from many unique pieces of deoxyribonucleic acid (DNA) [2,3,4,5,6]: here the chemical composition of the system determines the shape of the units that form through self-assembly
The results presented in this paper indicate that the preferred adsorption of particles can be switched by changing surface receptor concentration, provided that one particle has few strong-binding ligands, while the second has many weak-binding ligands

Summary

Introduction

Systems comprising many different chemical ingredients may exhibit complex physical behaviour that is absent in systems with fewer components. DNA-coated colloids are an example of synthetic, multivalent building blocks [9,10,11,12,13] that can self-assemble In these systems, complementary single-stranded DNA is grafted to the surfaces of colloids or nanoparticles, resulting in a system that selfassembles over a narrow temperature range into aggregate structures “encoded” by the DNA ligands. A recent experimental study has demonstrated size-selective surface binding and patterning from a bimodal mixture of DNA-coated nanoparticles, depending on the local density of receptor DNA strands on the surface [14]. Because of their sensitivity to the nature and surface-concentration of receptors, multivalent particles are well suited for chemical and biological sensing [15]. The paper concludes by discussing possible applications of multivalent switches

Theory

Lattice model for ligand-receptor binding

Results & discussion

Conclusions