Tuning colloidal association with specific peptide interactions

Coiled-coil leucine zipper domains are well-studied molecular recognition motifs that are attractive candidates for incorporation into engineered self-assembly systems due to their modular nature and wide range of binding affinities. Here, we investigate the ability of this peptide family to induce and control the specific association of micron-sized building blocks. Individual microparticles are functionalized with multiple copies of one particular leucine zipper motif which is capable of self-assembling through dimerization. We find that the dissociation temperature of the peptide-functionalized microparticles is considerably higher than the melting temperature of free peptide dimers in solution, which is a signature of the multivalent nature of the peptide-mediated particle interactions. We further demonstrate that titrating in freely soluble peptides to the peptide-coated bead suspensions can tune the particle association at constant temperature, pH, and ionic strength. While the high dissociation temperature of peptide-functionalized micro-objects may make global temperature control challenging, this ‘competition control’ with freely soluble peptides offers an attractive alternative to fine-tune the colloidal self-assembly with additional particle-specificity.