Fluorescent monolayer protected gold nanoparticles – Preparation and structure elucidation

Angelova, Polina; Kuchukova, N.; Dobrikov, Georgi M.; Timtcheva, I.; Kostova, Kalina; Petkova, Irina; Vauthey, Eric

doi:10.1016/j.molstruc.2010.12.019

Cited by 6 publications

(2 citation statements)

References 35 publications

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“…Synthesis and purification of 2-[4-(5-phenyloxazol-2-yl)phenyl]-3-hydroxychromone ( 1 ) and 2-(benzimidazol-2-yl)-3-hydroxychromone ( 2 ) (Figure b) was described elsewhere. − The dodecanethiol-functionalized AuNPs were prepared by the following method: , Solution of tetraoctylammonium bromide (0.3 g) in 30 mL of toluene was mixed with solution of 0.11 g of HAuCl 4 ·3H 2 O in water (25 mL). The mixture was stirred for 10 min at room temperature, and then the decolorized water layer was moved off.…”

Section: Methodsmentioning

confidence: 99%

Fluorescence Probing of Thiol-Functionalized Gold Nanoparticles: Is Alkylthiol Coating of a Nanoparticle as Hydrophobic as Expected?

et al. 2012

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Understanding the interaction of fluorescent dyes with monolayer-protected gold nanoparticles (AuNPs) is of fundamental importance in designing new fluorescent nanomaterials. Among a variety of molecular sensors and reporters, fluorescent probes based on a 3-hydroxychromone (3HC) skeleton appear to be very promising. They exhibit the phenomenon of dual band emission, resulting from excitedstate intramolecular proton transfer (ESIPT), known to be highly sensitive to a nature of microenvironment surrounding a fluorophore. In this study, dodecanethiol-protected gold nanoparticles were synthesized, and, owing to the transmission electron micrograph imaging, their average diameter was found to be ∼1.4 nm. Fluorescence titrations of the 3HC ESIPT probes with AuNPs in toluene solutions demonstrate significant changes in the intensity ratio of their normal and tautomeric emission bands, suggesting that the probe molecules become noncovalently bound to a dodecanethiol layer of AuNPs. Despite expected fluorescence quenching induced by close proximity to the metal surface, no fluorescence lifetime decrease was observed, indicating that a bound-fluorophore is shielded from a nanoparticle core. Further spectral analysis revealed that the ratiometric fluorescence changes could be interpreted as a consequence of intermolecular hydrogen bonding between a probe and residual ethanol molecules, trapped into the dodecanethiol shell of AuNPs during the synthesis. Evidences for residual traces of ethanol in the ligand shell of the nanoparticles were also observed in NMR spectra, suggesting that alkylthiol-coated gold nanoparticles may not be as hydrophobic as one could expect. To elucidate structural features of dodecanethiol-stabilized gold nanoparticles at the supramolecular level, a molecular dynamics (MD) model of AuNP was developed. The model was based on the all-atom CHARMM27 force field parameters and parametrized according to available experimental data of the synthesized AuNPs. Our MD simulations show that in bulk toluene the 3HC probe molecule becomes weakly bound to a dodecanethiol monolayer, so that a fluorophore favors residence in an outer shell of AuNP. In addition, MD simulations of transfer of AuNP from bulk ethanol to toluene demonstrate that a small population of ethanol molecules are able to penetrate deeply into the dodecanethiol layer and may indeed be trapped into the ligand shell of alkylthiolfunctionalized gold nanoparticles. The results of our fluorescence experiments and molecular dynamics simulation suggest that 3hydroxychromones can be used as a noncovalent fluorescent labeling agent for alkylthiol-stabilized noble metal nanoparticles.

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Section: Methodsmentioning

confidence: 99%

Fluorescence Probing of Thiol-Functionalized Gold Nanoparticles: Is Alkylthiol Coating of a Nanoparticle as Hydrophobic as Expected?

et al. 2012

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“…To this purpose, we used colloidal dispersions having extinction maxima at about 930-970 nm and exploited the high affinity of gold towards thiol-terminated molecules. In particular, we selected NAFTA8, a N-substituted 4-methoxy-1,8-napthalimide derivative (hereaer NF8) bearing a C8 aliphatic chain endowed with a thiol, which has been already tested on gold spherical nanoparticles 47 and, in its shorter version with a 6-aliphatic chain, on Au nanostars 40 and Au/Ag nanocages. 48 The molecular structure of NF8 is reported in Fig.…”

Section: Introductionmentioning

confidence: 99%