Differential Adhesion of Amino Acids to Inorganic Surfaces

Interactions at the interface of biological molecules and inorganic materials are an open question in materials science; creating and understanding these hybrid interfaces can have extensive basic science and practical implications. In an effort to develop this understanding, using fundamental inorganic and biological building blocks, we have systematically examined the adhesion of amino acids to a series of inorganic surfaces used in semiconductor device fabrication. Oligomeric peptides comprised of each of the twenty amino acids were exposed in solution to inorganic surfaces including metals, insulators, and semiconductors, and their adhesion following simple surface wash was measured. This extensive grid of results shows that substantial differential adhesion to the various inorganic material surfaces is observed for some of the amino acids, and for specific material surfaces the amino acids can show markedly different adhesion densities, with the adhesion determined largely by the side-chain charge properties of the amino acids. A complete mapping of these adhesion findings of amino acids versus materials for several different solution types is presented, and the properties of this adhesion with respect to concentration and pH are studied. These results provide an empirical basis for building structures at the peptide to inorganic material interface. In this vein, the data is then used to design an inorganic nano-structure that selectively binds to a prescribed primary sequence in a peptide. Preliminary results show that such an inorganic surface can be made at the molecular scale to which a specific peptide sequence will selectively adhere according to the overall adhesion properties described in this study.