Oxide-binding peptides are used to reversibly attach biomolecules to a variety of metal oxide surfaces (e.g., silica, alumina). This provides a means to functionalize oxide surfaces on the micron scale with a variety of biologically active molecules. Applications include biosensors and implantable medical devices, in addition to electronics, fuel cells, and catalysts. The peptides can also be used as a versatile affinity tag for use in bioassays that require protein separation and/or purification.
Coating inorganic surfaces (e.g., metal oxides) with functional proteins is a major challenge in the development of biosensors and bioassays. The chemical coupling required to link biological proteins to oxide surfaces is often complex and irreversible. Previously, protein affinity tags, such as poly-histidine (His)-tags, have been used as a simpler alternative to this chemical coupling. Generally, affinity tags are genetically incorporated into a protein of interest. They bind an affinity resin (e.g., a transition metal, in the case of His-tags), which allows for the separation and purification of the protein of interest. This method can also be used to conjugate proteins to useful substrates for which the tags have affinity. His-tags in particular are capable of conjugating proteins to quantum dots and polymer surfaces. However, His-tags do not promote high-affinity adherence to all surfaces, including many common substrates in biological applications. In this invention, oxide-binding peptides provide an improvement upon existing affinity tags. They can adhere to proteins with nanomolar affinity and link them to a variety of oxide surfaces such as silicon dioxide (SiO2) and indium tin oxide (ITO), used in applications that range from microelectronics to the food industry. The binding of these peptides is versatile, reversible, and does not require any further chemistry on the surface of the protein.
Biomolecules have a unique innate ability to direct the organization of inorganic solids (e.g., teeth). Harnessing the molecular recognition and self-assembly inherent to these systems allows for the development of advanced materials with the potential to surpass their chemically synthesized counterparts. Oxide-binding peptides have been developed and selected for their ability to reversibly couple biomolecules to metal oxide surfaces. Peptide binding is achieved via electrostatic interactions at the oxide surface mediated via basic amino acid residues. The technology is a single-step alternative to the complex covalent coupling typically used in the assembly of biosensors. It can also be used to generate novel materials with a range of desired physical characteristics dependent upon the selected peptide and oxide substrate.
- Versatile and reversible binding (as opposed to chemical coupling)
- Highly specific, nanomolar-scale binding affinity; (His-tags bind with micromolar affinity)
- Can be used with common substrates such as silicon dioxide (silica) and aluminum oxide (alumina)