Thermodynamic study of interactions between ZnO and ZnO binding peptides using isothermal titration calorimetry

Whilst material specific peptide binding sequences have been identified using a combination of combinato-rial methods and computational modelling tools, a deep molecular level understanding of the fundamental principles through which these interactions occur and in some instances modify the morphology of inorganic materials is far from being fully realized. Understanding the thermodynamic changes that occur during peptide-inorganic interactions and correlating these to structural modifications of the inorganic materials could be the key to achieving and mastering con-trol over material formation processes. This study is a detailed investigation applying isothermal titration calorimetry (ITC) to directly probe thermodynamic changes that occur during interaction of ZnO binding peptides (ZnO-BPs) and ZnO. The ZnO-BPs used are reported sequences G-12 (GLHVMHKVAPPR), GT-16 (GLHVMHKVAPPR-GGGC) and alanine mutants of G-12 (G-12A6, G-12A11 and G-12A12) whose interaction with ZnO during solution synthesis studies have been extensively investigated. The interactions of the ZnO-BPs with ZnO yielded biphasic isotherms comprising both an endo-thermic and an exothermic event. Qualitative differences were observed in the isothermal profiles of the different pep-tides and ZnO particles studied. Measured ΔG values were between -6 and -8.5 kcal/mol and high adsorption affinity val-ues indicated the occurrence of favourable ZnO-BP-ZnO interactions. ITC has great potential in its use to understand peptide-inorganic interactions and with continued development, the knowledge gained may be instrumental for simplifi-cation of selection processes of organic molecules for the advancement of material synthesis and design

Generation and Characterization of a Library of Novel Biologically Active Functional Surfactants (Surfmers) Using Combined High-Throughput Methods

We report the first successful combination of three distinct high-throughput techniques to deliver the accelerated design, synthesis, and property screening of a library of novel, bio-instructive, polymeric, comb-graft surfactants. These three-dimensional, surface-active materials were successfully used to control the surface properties of particles by forming a unimolecular deep layer on the surface of the particles via microfluidic processing. This strategy deliberately utilizes the surfactant to both create the stable particles and deliver a desired cell-instructive behavior. Therefore, these specifically designed, highly functional surfactants are critical to promoting a desired cell response. This library contained surfactants constructed from 20 molecularly distinct (meth)acrylic monomers, which had been pre-identified by HT screening to exhibit specific, varied, and desirable bacterial biofilm inhibitory responses. The surfactant's self-assembly properties in water were assessed by developing a novel, fully automated, HT method to determine the critical aggregation concentration. These values were used as the input data to a computational-based evaluation of the key molecular descriptors that dictated aggregation behavior. Thus, this combination of HT techniques facilitated the rapid design, generation, and evaluation of further novel, highly functional, cell-instructive surfaces by application of designed surfactants possessing complex molecular architectures

Interactions between metal oxides and biomolecules: from fundamental understanding to applications

Metallo-oxide (MO) based bioinorganic nanocomposites promise unique structures, physico-chemical properties and novel bio-chemical functionalities and within the last decade, investment in research on materials such as ZnO, TiO2, SiO2 and GeO2 has significantly increased. Besides traditional approaches, the synthesis, shaping, structural patterning and post-processing chemical functionalization of the materials surface is inspired by strategies which mimic processes in nature. Would such materials deliver new technologies? Answering this question requires the merging of historical knowledge and current research from different fields of science. Practically, we need an effective defragmentation of the research area. From our perspective, the superficial accounting of material properties, chemistry of the surfaces and the behaviour of biomolecules next to such surfaces is a problem. This is particularly of concern when we wish to bridge between technologies in vitro and biotechnologies in vivo. Further, besides the potential practical technological efficiency and advantages such materials might exhibit, we have to consider the wider long-term implications of material stability and toxicity. In this contribution we present a critical review of recent advances in the chemistry and engineering of MO based biocomposites highlighting the role of interactions at the interface and the techniques by which these can be studied. At the end of the article we outline the challenges which hamper progress in research and extrapolate to developing and promising directions including additive manufacturing and synthetic biology that could benefit from molecular level understanding of interactions occurring between inanimate (abiotic) and living (biotic) materials

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 <i>in silico</i>. ZnO growth was monitored in the absence and presence of ZnO-BPs during solution synthesis using two different growth routes: the Zn­(NO₃)₂·6H₂O–HMTA system and the Zn­(CH₃COO)₂–NH₃ 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