The Characterization of Borohydride-Stabilized Nanosilvers in Laponite Sol Using¹H NMR: Its Ligand Exchange Reactions with MUA and TOP

Abstract

In borohydride-protected nanosilvers in laponite sol, the silver particles aggregate to form short chains and a dumbbell shape. The 1 H NMR measurements in this study represent, to our knowledge, the first observation of proton resonances of borohydride-protected nanosilvers in aqueous solution. Borohydride on nanosilver can be exchanged with 11-mercaptoundecanoic acid (MUA) or trioctylphosphine (TOP). Transmission electron microscopy and UV-Vis spectroscopy data show that the number of aggregated silver nanoparticles decreases upon addition of aforementioned ligands due to the formation of silver MPCs (monolayer-protected clusters). Adsorption of MUA or TOP on nanosilver is confirmed through the observation of broad proton resonances of MPCs in 1 H NMR spectra.

Smart pH- and Temperature-Sensitive Micelles Based on Chitosan Grafted with Fatty Acids to Increase the Efficiency and Selectivity of Doxorubicin and Its Adjuvant Regarding the Tumor Cells

“…In the FTIR spectra of chitosan-acid conjugates, broad, intense bands appear (in comparison with Chit5), corresponding to the O-H and N-H stretching oscillations, which correspond mainly to the bonds involved in the formation of hydrogen bonds [43,48,49], which is typical of micellar systems. The FTIR spectrum of oleic acid was presented earlier in the work [2]: the characteristic peaks at 2982, 2925, and 2857 cm −1 of the C-H stretching oscillations are shifted during conjugation (acid vs. chitosan-acid) to 2960-2965, 2913-2917, and 2848-2850 cm −1 , respectively, which indicates a dense packing of lipids in polymer structure, which corresponds to a transition to a more structured state with a dense lipid package just as in liposomes [50].…”

Solution NMR Spectroscopy with Isotope-Labeled Cysteine (13C and 15N) Reveals the Surface Structure of l-Cysteine-Coated Ultrasmall Gold Nanoparticles (1.8 nm)

“…Therefore, NMR spectroscopy as a comparatively new tool to study nanoparticles and metallic clusters has been applied to probe the ligand shell with high accuracy. , Unfortunately, the vicinity of the metallic particle usually often results in a substantial line broadening and, in consequence, to a loss of resolution of the NMR spectrum. Especially for larger particles, − the elucidation of the surface structure is hardly possible. If the particles are small enough, ,,,, characteristic resonances are observable and distinct ligand species can be identified.…”