ZnO Binding Peptides: Smart Versatile Tools for Controlled Modification of ZnO Growth Mechanism and Morphology

Material binding peptides are proving to have great potential in improving material synthesis and advancing device fabrication; however, their specificity and interaction mechanisms with target surfaces remain largely elusive. This study contributes to the developing understanding of fundamental principles through which ZnO binding peptides (ZnO-BPs) interact with and modify ZnO growth/morphology. The ZnO-BPs used were the reported phage display (PD) identified sequence (G-12 (GLHVMHKVAPPR) and its derivative, GT-16 (GLHVMHKVAPPR-GGGC)) as well as novel sequences generated from postselection modifications including alanine mutants of G-12 (G-12A6, G-12A11, and G-12A12) chosen on the basis of peptide stability calculated in silico . ZnO growth was monitored in the absence and presence of ZnO-BPs during solution synthesis using two different growth routes: the Zn(NO 3 ) 2 ·6H 2 O–HMTA system and the Zn(CH 3 COO) 2 –NH 3 system. The outcomes of the ZnO synthesis studies demonstrate that a single ZnO-BP can utilize different sequence and concentration dependent mechanisms to control ZnO growth and generate different morphologies. The specific synthesis system used dictated the species present in solution and the solid phases formed, some of which ZnO-BPs could interact with and consequently modify ZnO growth and resultant morphologies. The role of histidine within ZnO-BPs in interaction with ZnO and stabilization of LBZs is also demonstrated.