Sequence defined molecules such as peptides and peptoids enable significant control over the formation of inorganic nano-structured materials. The bio-inspired use of sequence defined molecules to synthesize inorganic nanoscale materials is motivated by the ability to form complex structures at mild reaction conditions. The sensitivity of syntheses to small changes in a molecule’s sequence makes these approaches both potent and difficult to leverage. Additionally, one needs to consider experimental parameters like solution conditions (pH, ionic concentration etc.) and reagent concentrations because these can significantly change how sequence defined molecules interact with inorganic precursors and nanoparticles. We posit that the design of sequence defined molecules for inorganic nanomaterial synthesis will be accelerated by integration of experimental automation and new data analysis methods. We believe that extended sampling will provide insights into the connection between molecular design and synthesis outcomes which would be missed or misinterpreted in experiments with limited sampling of experimental parameters. Therefore, we developed a model system in which Au nanoparticles are synthesized in the presence of Au binding peptides using a liquid handling robot. Our objective was to study the effects of targeted sequence changes and lipid tail conjugation in 5 variants of a Au binding peptide (Z2) across 64 different reagent combinations (concentration of precursor, reducing agent, and peptide). Each sample was characterized by UV-Vis spectroscopy which serves as a proxy for the structure of plasmonic nanoparticles. Functional principal component analysis and a graph Fourier transform were applied to the spectra to make quantitative comparisons between each of the peptides (7 in total) in the large experimental design space (448 samples). Finally, we validate this approach by analyzing key features of UV-Vis data, ultra-small-angle X-ray scattering (USAXS), and electron microscopy. Both of our approaches were in agreement that key changes to a peptide sequence have a more significant impact on synthesis outcomes than conjugation of a lipid tail. We also report on formation of fused anisotropic particles in the presence of a peptide variant in which amino acids that were identified as key to Au binding were substituted by amino acids with similar physicochemical properties.

Multivariate Analysis of Peptide-Driven Nucleation and Growth of Au Nanoparticles

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.