Peptides to bridge biological-platinum materials interface

Peptides with inorganic materials recognition already started to impact a wide range of surface-related technologies ranging from biomonitoring to biomedical areas. Combinatorial biology-based libraries are the initial step in tempting the directed evolution of peptides with specific interactions towards technologically relevant materials. Here, a case study is provided to demonstrate the specific peptide binding and the amino acids residues that play an important role for platinum surface affinity by combining computational as well as genetic engineering tools. Using a phage display technique, septapeptides were identified exhibiting affinity to noble metal platinum, and the amino acid distributions in the identified peptides were analyzed. The analysis of the peptide sequences showed that strong Pt-binding peptides contain positively charged, hydrophilic, and polar residues, and especially enriched in threonine, serine, and glutamine. Under competitive surface-binding conditions, strong Pt-binding peptide motif displayed on phage resulted in high specificity to Pt regions on a Pt-macropatterned glass. Conformational analysis of the strong binder indicates that threonine and serine as well as glutamine are in close contact with the surfaces forming a tripod molecular architecture. The alanine substitution mutagenesis applied at the genomic level to the peptide displayed on the phage revealed threonine and serine substitutions as the critical ones. Understanding the residue-based interactions of the peptide sequences can be utilized to tune the affinity and the specificity of the peptides with the inorganic surfaces, toward making them indispensable molecular tools to control the molecular interactions of biological macromolecules with the material surfaces.