Stimuli Responsive Hierarchical Assembly of P22 Virus-like Particles

Biomimetic systems responsive to environmental stimuli are of growing interest due to their useful, intriguing, and sometimes unexpected properties. Hierarchical self-assembly of biological building blocks has emerged as a powerful means of creating biomaterials with collective properties. Here, we show P22 virus-like particles (VLPs) functionalized with a spider silk protein derivative on the capsid exterior assemble into a hierarchical structure due to spider silk/spider silk interactions at low pH and reversibly dissemble upon raising the pH. We also show that the capsid arrays can be assembled through electrostatic interaction between the negatively charged capsids and a positively supercharged GFP mutant and can be reversed by raising the ionic strength. Most notably, we found that the supercharged GFP could bind to the hierarchically assembled material under high salt conditions but not to the individual capsids under the same high salt conditions. The binding of the charged macromolecule under high salt conditions demonstrates a collective behavior of the hierarchically assembled system that is not present with the unassembled, individual components of the system.