Identification of Indium Tin Oxide Nanoparticle-Binding Peptides via Phage Display and Biopanning Under Various Buffer Conditions

: Recent advances in biotechnology have enabled the rapid identification of peptides that bind to inorganic materials. Here, we aimed to identify peptides that bind to indium tin oxide (ITO) nanoparticles via different binding mechanisms, using phage display and biopanning, under five different buffer conditions. Three types of ITO-binding peptides (ITOBPs) were selected from 10 types of identified peptide candidates for characterization. These included ITOBP8, which had an acidic isoelectric point, and was identified when a buffer containing guanidine was used, and ITOBP6 and ITOBP7, which contained a His-His-Lys sequence at their N-termini, and were identified when a highly concentrated phosphate elution buffer with a low ionic strength was used. Among these peptides, ITOBP6 exhibited the strongest ITO-binding affinity (dissociation constant, 585 nmol/L; amount of protein bound at saturation, 17.5 nmol/m2-ITO particles). These results indicate that peptides with specific binding properties can be obtained through careful selection of the buffer conditions in which the biopanning procedure is performed. Further examination is needed to determine the suitability of this approach for the rapid identification of metal oxide-binding peptides.