Coating gold nanorods with self-assembling peptide amphiphiles promotes stability and facilitates <i>in vivo</i> two-photon imaging

Egorova, E. A.; Arias-Alpizar, Gabriela; Vlieg, Redmar C.; Gooris, Gert S.; Bouwstra, Joke A.; Noort, John van; Kros, Alexander; Boyle, Aimee L.

doi:10.1039/d2tb00073c

Cited by 3 publications

(3 citation statements)

References 55 publications

(88 reference statements)

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“…Mass spectrometry and amino acid analysis can provide an average estimate of the number of peptides per AuNP . Quantifying unbound ligands remaining in the supernatant offers a mass balance approach to obtaining a similar result. ,, In combination, these analytical techniques can provide evidence of successful peptide conjugation to the AuNP surface. Nevertheless, robust data showing the density and packing of peptides on the AuNP surface are lacking and perhaps can be addressed with nuclear magnetic resonance (NMR) spectroscopy and scanning-transmission electron microscopy–electron energy loss spectroscopy (STEM-EELS) characterization as discussed below.…”

Section: Categories Of Soft Surface Coatings and Ligandsmentioning

confidence: 99%

The Landscape of Gold Nanocrystal Surface Chemistry

et al. 2023

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Conspectus Gold nanoparticles (AuNPs) exhibit unique size- and shape-dependent properties not obtainable at the macroscale. Gold nanorods (AuNRs), with their morphology-dependent optical properties, ability to convert light to heat, and high surface-to-volume ratios, are of great interest for biosensing, medicine, and catalysis. While the gold core provides many fascinating properties, this Account focuses on AuNP soft surface coatings, which govern the interactions of nanoparticles with the local environments. Postmodification of AuNP surface chemistry can greatly alter NP colloidal stability, nano-bio interactions, and functionality. Polyelectrolyte coatings provide controllable surface-coating thickness and charge, which impact the composition of the acquired corona in biological settings. Covalent modification, in which covalently bound ligands replace the original capping layer, is often performed with thiols and disulfides due to their ability to replace native coatings. N-heterocyclic carbenes and looped peptides expand the possible functionalities of the ligand layer. The characterization of surface ligands bound to AuNPs, in terms of ligand density and dynamics, remains a challenge. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for understanding molecular structures and dynamics. Our recent NMR work on AuNPs demonstrated that NMR data were obtainable for ligands on NPs with diameters up to 25 nm for the first time. This was facilitated by the strong proton NMR signals of the trimethylammonium headgroup, which are present in a distinct regime from other ligand protons’ signals. Ligand density analyses showed that the smallest AuNPs (below 4 nm) had the largest ligand densities, yet spin–spin T2 measurements revealed that these smallest NPs also had the most mobile ligand headgroups. Molecular dynamics simulations were able to reconcile these seemingly contradictory results. While NMR spectroscopy provides ligand information averaged over many NPs, the ligand distribution on individual particles’ surfaces must also be probed to fully understand the surface coating. Taking advantage of improvements in electron energy loss spectroscopy (EELS) detectors employed with scanning transmission electron microscopy (STEM), a single-layer graphene substrate was used to calibrate the carbon K-edge EELS signal, allowing quantitative imaging of the carbon atom densities on AuNRs with sub-nanometer spatial resolution. In collaboration with others, we revealed that the mean value for surfactant-bilayer-coated AuNRs had 10–30% reduced ligand density at the ends of the rods compared to the sides, confirming prior indirect evidence for spatially distinct ligand densities. Recent work has found that surface ligands on nanoparticles can, somewhat surprisingly, enhance the selectivity and efficiency of the electrocatalytic reduction of CO2 by controlling access to the active site, tuning its electronic and chemical environment, or denying entry to impurities that poison the nanoparticle surface to facilitate ...

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Section: Categories Of Soft Surface Coatings and Ligandsmentioning

confidence: 99%

The Landscape of Gold Nanocrystal Surface Chemistry

et al. 2023

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“…20,50 Gold nanorods (GNRs) were synthesised via the two-step seed-mediated approach. 31 2-3 nm seeds were prepared by mixing CTAB (5 mL, 0.20 M), and HAuCl 4 (5 mL, 0.50 mM) with ice-cold NaBH 4 (0.60 mL, 10 mM) whilst intensely stirring at room temperature. Aer 2 min of vigorous stirring, the solution was le undisturbed at room temperature for 2 hours.…”

Section: Gold Nanoparticles Synthesismentioning

confidence: 99%

“…Previously, we reported the use of thiolated peptide amphiphiles as stabilisers for both GNPs and GNRs. 30,31 These coatings insulate the gold surface, prevent particle aggregation under harsh conditions (up to 3 M NaCl, or 1 M competing thiols), and provide GNPs with surface chemistry described as "protein-like". 32 Published data suggest that biologically active moieties displayed on the surface of peptidecapped GNPs preserve their biological function and their availability, [32][33][34][35] and that GNPs do not impair immune functions of DCs or B cells.…”

Section: Introductionmentioning

confidence: 99%