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The aggregation of plasmonic nanoparticles can lead to new and controllable properties useful for numerous applications. We recently showed the reversible aggregation of gold nanoparticles (AuNPs) via a small, cationic di-arginine peptide; however, the mechanism underlying this aggregation is not yet comprehensively understood. Here, we seek insights into the intermolecular interactions of cationic peptide-induced assembly of citrate-capped AuNPs by empirically measuring how peptide identity impacts AuNP aggregation. We examined the nanoscale interactions between the peptides and the AuNPs via UV-vis spectroscopy to determine the structure-function relationship of peptide length and charge on AuNP aggregation. Careful tuning of the sequence of the di-arginine peptide demonstrated that the mechanism of assembly is driven by a reduction in electrostatic repulsion. We show that acetylated N-terminals and carboxylic acid C-terminals decrease the effectiveness of the peptide in inducing AuNP aggregation. The increase in peptide size through the addition of glycine or proline units hinders aggregation and leads to less redshift. Arginine-based peptides were also found to be more effective in assembling the AuNPs than cysteine-based peptides of equivalent length. We also illustrate that aggregation is independent of peptide stereochemistry. Finally, we demonstrate the modulation of peptide-AuNP behavior through changes to the pH, salt concentration, and temperature. Notably, histidine-based and tyrosine-based peptides could reversibly aggregate the AuNPs in response to the pH.
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This content will become publicly available on May 8, 2026
Interplay of Hydrophobicity, Charge, and Sequence Length in Oligopeptide Coassembly
Peptide coassembly offers novel opportunities for designing advanced nanomaterials. This study used coarse-grained molecular dynamics simulations to examine the coassembly of charge-complementary peptides, assessing various ratios and the role of charge and hydrophobicity in their aggregation. We discovered that peptide length, charge, and hydrophobicity significantly influence coassembly behavior, with more hydrophobic peptides exhibiting greater aggregation despite electrostatic repulsion. Beyond the coassembly of two peptides, we also observed that the coassembly of more than two peptides will likely lead to new assembly structures and properties. Our findings underscore the importance of peptide composition and length in tuning the coassembly and the resulting properties, thus facilitating the design of complex peptide nanoparticles for biomedical and biotechnological applications.
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- Award ID(s):
- 2317652
- PAR ID:
- 10614824
- Publisher / Repository:
- ACS
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry B
- Volume:
- 129
- Issue:
- 18
- ISSN:
- 1520-6106
- Page Range / eLocation ID:
- 4383 to 4391
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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