Multivalent weak interactions enhance selectivity of interparticle binding

Targeted drug delivery critically depends on the binding selectivity of cargo-transporting colloidal particles. Extensive theoretical work has shown that two factors are necessary to achieve high selectivity for a threshold receptor density: multivalency and weak interactions. Here, we study a model system of DNA-coated particles with multivalent and weak interactions that mimics ligand–receptor interactions between particles and cells. Using an optomagnetic cluster experiment, particle aggregation rates are measured as a function of ligand and receptor densities. The measured aggregation rates show that the binding becomes more selective for shorter DNA ligand–receptor pairs, proving that multivalent weak interactions lead to enhanced selectivity in interparticle binding. Simulations confirm the experimental findings and show the role of ligand–receptor dissociation in the selectivity of the weak multivalent binding.