pH-insensitive fabrication of gold nanoparticles with high concentration by ultrasound-assisted electrochemical process via aid of chitosan

Yang, Kuang-Hsuan,Liu, Yu-Chuan,Hsu, Ting-Chu,Tsai, Huei-Ian

, p. 63 - 68 (2010)

In this work, we report a new pathway to prepare pure gold nanoparticles with high concentrations in acid solutions via the aid of chitosan without the addition of other stabilizers and reductants based on electrochemical methods. Interestingly, this fabrication of gold nanoparticles with high concentrations in solutions is pH-insensitive. The characteristics of prepared gold nanoparticles were examined by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (HRXPS) measurements. Experimental results indicate the concentration and the particle size of Au nanoparticles prepared in 0.1N HCl are ca. 50 ppm and 12 nm in diameter, respectively. Similar experiment performed in 0.1N NaCl with the aid of chitosan shows that the corresponding concentration of prepared Au nanoparticles is ca. 100 ppm. Further similar experiments performed in 0.1N HCl and 0.1N NaCl without the aid of chitosan show that the corresponding concentrations of prepared Au nanoparticles are ca. 1 and 60 ppm, respectively.

Gold(III) extraction by 1,3-Bis(2'-acetoxymethylthiobutyl-3'- thiobutylpropyl)-6-methyluracyl from hydrochloric acid solutions

Khisamutdinov,Murinov,Baikova

, p. 1798 - 1802 (2007)

Gold(III) extraction by 1,3-bis(2'-acetoxymethylthiobutyl-3'- thiobutylpropyl)-6-methyluracyl from 0.5 M HCl solutions to chloroform is studied. The reagent has a high efficiency, separates gold(III) ions from the sum of nonprecious and ferrous metals, and can be repeatedly used after stripping. The extraction mechanism is solvation, with Au-S coordination bonds formed with all sulfur atoms of the reagent; the solvation number changes from 1 to 0.25 with increasing gold(III) aqueous concentration.

Photooxidation of dicyanoaurate(I) induced by metal-to-ligand charge transfer excitation

Kunkely, Horst,Vogler, Arnd

, p. 853 - 855 (1998)

The irradiation of [Au(CN)2]- in oxygen-saturated acetonitrile leads to photooxidation of Au(I). In the presence of additional chloride [Au(CN)2Cl2]- is formed with φ = 0.5 × 10-4 at λ

Mixed valent gold oxides: Syntheses, structures, and properties of Rb5Au3O2, Rb7Au5O2, and Cs7Au5O2

Mudring, Anja-Verena,Nuss, Juergen,Wedig, Ulrich,Jansen, Martin

, p. 29 - 36 (2000)

The title compounds Rb5Au3O2, Rb7Au5O2, and Cs7Au5O2 are the first examples of mixed valent phases containing gold in the oxidation states +1 and -1. Their

Annibale, Giuliano,Natile, Giovanni,Cattalini, Lucio

, (1976)

Ionic gold demonstrates antimicrobial activity against Pseudomonas aeruginosa strains due to cellular ultrastructure damage

Torres, Miguel Reyes,Slate, Anthony J.,Ryder, Steven F.,Akram, Maliha,Iruzubieta, Conrado Javier Carrascosa,Whitehead, Kathryn A.

, p. 3015 - 3024 (2021)

Due?to the ever-increasing rise of antimicrobial?resistant (AMR)?bacteria, the?development of?alternative antimicrobial agents is a global priority. The antimicrobial activity of ionic gold was explored against four Pseudomonas aeruginosa strains with different AMR profiles in order?to determine the antimicrobial activity of ionic gold and elucidate the mechanisms of action. Disc diffusion assays (zone of inhibition: ZoI) coupled with minimum inhibitory/bactericidal concentrations (MIC/MBC) were conducted to determine the antimicrobial efficacy of ionic gold. Scanning electron microscopy (SEM) was used to visualise morphological changes to the bacterial cell ultrastructure. Strains with increased AMR were slower to grow?which is likely a?fitness cost due to?the enhanced AMR activity. Although greater concentrations of ionic gold were required to promote antimicrobial activity, ionic gold demonstrated similar antimicrobial values?against all strains tested. Lowry assay results indicated that protein leakage was apparent following incubation with ionic gold, whilst SEM revealed?cellular ultrastructure damage. This study suggests that the application of ionic gold as an alternative antimicrobial?is promising, particularly against AMR P. aeruginosa. The antimicrobial activity of ionic gold against P. aeruginosa could potentially be utilised as an alternative therapeutic option in wound management, an approach that could benefit healthcare systems worldwide.

Ring opening and displacement by chloride of the bidentate chelate ligand from dichloro[pyridine-2-(α-methoxymethanolato)]gold(III) - A kinetic and mechanistic study

Marangoni, Giampaolo,Pitteri, Bruno,Annibale, Giuliano,Bortoluzzi, Marco

, p. 765 - 771 (2006)

The kinetics of ring opening and displacement of the bidentate chelate ligand from dichloro[pyridine-2-(α-methoxymethanolato)]gold(III) [Au(N-O)Cl2] (1) have been studied spectrophotometrically in methanol/water (95:5, v/v) at 25°C and constant ionic strength (I = 1 mol dm-3, LiClO4). In the presence of LiCl and perchloric acid the reaction consists of a pre-equilibrium protonation of the coordinated oxygen followed first by ring opening at oxygen accompanied by the entry of chloride or solvent and fast acetalisation of the hemiacetalic form of the ligand to give [AuCl3(N-OMe)], and then by displacement of the N-bonded ligand to give [AuCl4]-. The ligand is not displaced in the absence of chloride and no reaction is observed in the presence of chloride alone. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Redispersion of transition metal nanoparticle catalysts in tetraalkylphosphonium ionic liquids

Banerjee, Abhinandan,Theron, Robin,Scott, Robert W. J.

supporting information, p. 3227 - 3229 (2013/05/08)

Despite the fact that particle sintering is one of the most common events leading to the deactivation of metal nanoparticle (NP) catalysts, there is a paucity of studies investigating potential routes for the regeneration of smaller, catalytically active nanoparticles from larger particles formed after repeated catalytic cycles. Here, we reveal a simple yet elegant technique for the 'redispersion' of sintered NPs in tetraalkylphosphonium halide ionic liquids (ILs). The procedure described can use environmentally benign oxidants, be carried out at mild temperatures, and is shown to be applicable to a large number of catalytically important transition metals. TEM and UV-Vis spectroscopy reveal that this methodology can indeed regenerate smaller NPs from sintered systems. A sample catalytic reaction reveals that the redispersed NPs are as catalytically active as they were prior to sintering.