Nanoparticles and bottom-up synthesis techniques of materials often involve exogenous reagents that do not end up incorporated into the final material. This includes the traditional peptide-mediated gold material synthesis where sodium borohydride is added after peptide ion complexation time. Recent advances in peptide-mediated gold materials have shown that Au binding peptides like AuBP1 (WAGAKRLVLRRE) and AuBP2 (WALRRSIRRQSY) have the capacity to eliminate all exogenous reagents to generate colloidal suspensions where the non-covalent interactions of the peptide modulate the properties of the material at the abiotic/biotic interface. These studies identify that the position of the tryptophan residue in the sequence, as well as the pH of the aqueous solution and ions present in solution all, effect the rate of material reduction. Tryptophan is a relevant reducing agent for the synthesis of peptide-mediated gold nanoparticles, but can tryptophan be appended to non-gold specific peptides to induce the reduction of Au3+ to Au0? Here in we present the effects of peptide sequence homology on the reduction capacity of Au3+ to Au0 where the localized surface plasmon resonance was tracked for over time. Additionally, fluorescence quenching studies of these tryptophan mutated non-Au specific peptides were used to study how the sequence and binding affinity of the mutated peptide may correlate to the rate of reduction observed in the time-resolved plasmon. Finally, transmission electron microscopy (TEM) was performed to identify how the homology of the peptide sequence effects the final material morphology. Collectively, these results show that the entire peptide works in concert to control the reduction process of the Au material and that the sequence of the peptide is important to how the tryptophan residue will react in the presence of Au3+. By advancing the understanding of the conditions required for a biomimetic reduction process of Au materials, an evolution in material design may be possible.

Amino acid homology of peptide sequence as a determining factor in single pot reduction of Au nanoparticles

256th National Meeting (2018)

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