Controlling the Surface Functionalization of Ultrasmall Gold Nanoparticles by Sequence‐Defined Macromolecules

Abstract

Ultrasmall gold nanoparticles (diameter about 2nm) were surface-functionalizedw ith cysteine-carrying precision macromolecules. These consistedo fs equence-defined oligo(amidoamine)s (OAAs)w ith either two or six cysteine molecules for binding to the gold surface and either with or withoutaPEG chain (3400 Da). They were characterized by 1 HNMR spectroscopy, 1 HNMR diffusion-ordered spectroscopy (DOSY), small-angle X-ray scattering(SAXS), and high-resolution transmission electron microscopy.T he number of precision macromolecules per nanoparticle was determined after fluorescent labeling by UV spectroscopya nd also by quantitative 1 HNMR spectroscopy.E ach nanoparticle carried between4 0a nd 100 OAA ligands, depending on the number of cysteine units per OAA.T he footprint of each ligandw as about 0.074 nm 2 per cysteinem olecule. OAAs are well suited to stabilize ultrasmall gold nanoparticlesb ys electives urface conjugation and can be used to selectively cover their surface. The presence of the PEG chain considerably increasedt he hydrodynamicd iametero fb oth dissolved macromolecules and macromolecule-conjugated gold nanoparticles.

Water-Based Synthesis of Ultrasmall Nanoparticles of Platinum Group Metal Oxides (1.8 nm)

“…The crystallographic nature of the nanoparticles was determined by XRD. Although the particles were very small, causing extremely broad diffraction peaks, a quantitative analysis by Rietveld refinement was still possible. ,,− Figure shows the corresponding diffractograms.…”

“…Nanoparticles of noble metal oxides are of high importance in materials science, for example, in heterogeneous catalysis or electrocatalysis. Their reactivity occurs mainly on their surface; therefore, it is important to create them with a small particle size (“ultrasmall”) that in turn leads to a high specific surface area. − Furthermore, ultrasmall metallic nanoparticles, usually consisting of metallic gold, − have been proposed for biomedical applications, for example, to target proteins or tissues . With ultrasmall silver nanoparticles, a possible bactericidal effect of silver can be exploited. − In general, such small particles with a size of less than 2 nm are close to the size of metalloid clusters with atom-sharp composition. − …”

Dibenzyldithiocarbamate-Functionalized Small Gold Nanoparticles as Selective Catalysts for the Electrochemical Reduction of CO2 to CO

“…For comparison purposes, the value calculated for a single Citrate-Au NP ( D ∼ 3.6 nm) was 2.33 Å (Figure S3), which matches the one estimated by XRD and expected for d 111 . The interplanar spacing ( d 111 ) estimated for DBDTC-Au-1.6 was lower than the value expected for a bulk fcc structure, but also it was lower than that calculated for a similar-sized ultrasmall thiol-protected gold nanoparticle (1.66 ± 0.28 nm), 2.32 Å, in literature . The authors were able to estimate this value from FFT and the electron diffraction pattern using aberration-corrected electron microscopy.…”

“…The interplanar spacing (d 111 ) estimated for DBDTC-Au-1.6 was lower than the value expected for a bulk fcc structure, but also it was lower than that calculated for a similar-sized ultrasmall thiol-protected gold nanoparticle (1.66 ± 0.28 nm), 2.32 Å, in literature. 36 The authors were able to estimate this value from FFT and the electron diffraction pattern using aberration-corrected electron microscopy. Such approach is essential during HRTEM measurements of small clusters, since the analysis of these materials is mainly limited by the contrast of the image.…”

Photo‐Induced Microfluidic Production of Ultrasmall Glyco Gold Nanoparticles

“…In Figure 2 we report and compare the 1 H NMR spectra recorded on 1‐Man and 1‐Man‐UAuNPs. The strong broadening of the proton resonances in the direct surroundings of thiol groups of the ligand (2.626 and 2.484 ppm for Hβ of mannose‐EG 6 C 11 and OH‐EG 6 C 11 , respectively) confirm the binding of ligand 1‐Man to the gold nanoparticle (Figure 2, lower panel) [33] . The quantification of the bound mannose‐derivative on each ultrasmall gold nanoparticle was achieved by exploiting a quantitative 1 H NMR study (ERETIC2, Supporting Information).…”