Selective decoration and release of His-tagged proteins from metal-assembled collagen peptide microflorettes

Materials that mimic the extracellular matrix may serve as ideal delivery vehicles for biopolymers with biomedical applications. Herein we investigate dual His-tagged protein modification and release of metal-triggered, collagen peptide microflorettes by taking advantage of unsatisfied metal/ligands on or within the microflorette structures. Using GFP and RFP as model proteins for visualization, microflorettes were treated with His-tagged proteins either during or after particle assembly. Fluorescence microscopy confirmed the essential role of the His-tag in protein functionalization of the florettes, and confocal microscopy demonstrated distinct labeling zones either within the core or on the surface of the particles depending on their mode of synthesis. The location of the His-tagged proteins within the microflorettes was found to strongly influence the rate of release of these proteins from the particles, with the surface-localized proteins demonstrating faster release in comparison to the core-localized proteins. We have demonstrated, therefore, dual His-tagged protein functionalization with spatial control within metal-triggered, collagen peptide microflorette structures, and temporally controlled release of these proteins into biological media.