Researchers using the XSD 11-ID-C beamline at the APS are examining the sequence-dependent structure/function relationships of peptide-enabled nanoparticles (NP) through integrated experimental characterization and advanced molecular simulations.
The methodology demonstrated could readily be translated to other inorganic nanoparticle (NP)-peptide systems, paving the way for the development of rational sequence design rules for materials property enhancement.
Bio-enabled routes for nanomaterial synthesis and assembly comprise an area of increasing interest as a versatile strategy to create materials with enhanced and emergent properties under environmentally benign conditions.The complexity, specificity, and materials recognition properties of biomolecules allow for potential rational design routes that are not readily achieved using conventional nanoparticle (NP)/ligand combinations.
Peptide-enabled nanoparticle (NP) synthesis routes can create and/or assemble functional nanomaterials under environmentally friendly conditions, with properties dictated by complex interactions at the biotic/abiotic interface. Manipulation of this interface through sequence modification can provide the capability for material properties to be tailored to create enhanced materials for energy, catalysis, and sensing applications. Fully realizing the potential of these materials requires a comprehensive understanding of sequence-dependent structure/function relationships that is presently lacking. In this work, the atomic-scale structures of a series of peptide-capped Au NPs are determined using a combination of atomic pair distribution function analysis of high-energy X-ray diffraction data and advanced molecular dynamics (MD) simulations. The Au NPs produced with different peptide sequences exhibit varying degrees of catalytic activity for the exemplar reaction 4-nitrophenol reduction.
The experimentally derived atomic-scale NP configurations reveal sequence-dependent differences in structural order at the NP surface. Replica exchange with solute-tempering MD simulations are then used to predict the morphology of the peptide overlayer on these Au NPs and identify factors determining the structure/catalytic properties relationship. We show that the amount of exposed Au surface, the underlying surface structural disorder, and the interaction strength of the peptide with the Au surface all influence catalytic performance. A simplified computational prediction of catalytic performance is developed that can potentially serve as a screening tool for future studies. Our approach provides a platform for broadening the analysis of catalytic peptide-enabled metallic NP systems, potentially allowing for the development of rational design rules for property enhancement.
Nicholas M. Bedford, Zak E. Hughes, Zhenghua Tang, Yue Li, Beverly D. Briggs, Yang Ren, Mark T. Swihart, Valeri G. Petko, Rajesh R. Naik, Marc R. Knecht and Tiffany R. Walsh, “Sequence-Dependent Structure/Function Relationships of Catalytic Peptide-Enabled Gold Nanoparticles Generated under Ambient Synthetic Conditions,” The Journal of the American Chemical Society, Article ASAP, DOI: 10.1021/jacs.5b09529, Published Online December 17, 2015.