Tether: A Modular Synthesis Strategy for Inorganic Nanomaterials Using Biomolecules

Natural systems often utilize a single protein to perform multiple functions. Control over functional specificity is achieved through interactions with other proteins at well-defined epitope binding sites to form a variety of functional co-assembled structures. Inspired by the biological use of epitope recognition to perform diverse yet specific functions, we present Template Engineering Through Epitope Recognition (TEThER), a strategy that takes advantage of noncovalent, molecular recognition between different components to achieve functional versatility from a single protein template.

Engineered TEThER peptides are designed to serve as molecular bridges between protein epitope binding sites and the surrounding environment in a localized, specific, and versatile manner. The peptides discussed in this work are bifunctional sequences that span the biologic-inorganic interface by noncovalently binding to specific recognition sites on the protein scaffold and serving as sites for localized bio-enabled nucleation and growth of inorganic nanomaterials.

Clathrin, a protein that plays a key role in the dynamic remodeling of the cell membrane during endocytosis, provides a framework that offers access to a variety of architectures outside of a cell, such as cages, barrels, tetrahedra, and cubes. This structural diversity makes clathrin an attractive candidate for use as a versatile protein scaffold. Formation of these architectures is achieved by modulating environmental conditions to induce self-assembly (pH, concentration, ionic strength). We have begun a systematic study of these environmental conditions to gain an understanding of the kinetic and thermodynamic principles of self-assembly and predictive, controllable structuring of clathrin.

We functionalized self-assembled clathrin protein cages at specific sites through co-assembly with designer TEThER peptides to achieve three diverse functions: the bio-enabled synthesis of gold, cobalt oxide, and anatase titanium dioxide nanoparticles in aqueous solvents at room temperature and ambient pressure. Compared with previous demonstrations of site-specific bio-enabled inorganic synthesis, the TEThER strategy relies solely on defined, noncovalent interactions without requiring any genetic or chemical modifications to the protein template. Therefore, this design strategy represents a mix-and-match, biomimetic approach to achieve versatile and site-specific functionalization that can be broadly applied to other protein templates to generate structures with a range of functionalities.