Development of Catalytically Active Silver Colloid Nanoparticles Stabilized by Dextran

Abstract

Colloidal silver nanoparticles (Ag-NPs) with a mean diameter of 6.1 nm and a narrow size distribution were prepared by reduction of the correspondent metal salt with injection of NaBH(4), in the presence of dextran, and characterized by UV-vis, TEM, and DLS. The concentration of all reactants involved in the formation of the nanoparticles was optimized with the use of a new multivariate method, which revealed a significant reduction in the number of experiments when compared with the vast majority of univariate methods described in the literature. The Ag-NPs-dextran composite was able to efficiently catalyze the p-nitrophenol reduction in water by NaBH(4) with a rate constant normalized to the surface area of the nanoparticles per unit volume (k(1)) of 1.41 s(-1) m(-2) L, which is higher than values ever reported for Ag-NPs catalytic systems.

Polymer-coated palladium nanoparticle catalysts for Suzuki coupling reactions

“…Interestingly, the induction time detected for PdNP systems is either absent (or too short to be detected using the experimental setup of this study) or it is significantly shorter than that registered for other metallic nanoparticles, such as gold [17], silver [4,25] and platinum [18].…”

“…A typical absorption band centered at 400 nm appears when Nip is in a medium which is sufficiently basic to shift the aqueous dissociation equilibrium towards the p-nitrophenolate ion [18,25]. The reduction to the p-aminophenolate ion is accompanied by two main absorbance variations: a decrease at 400 nm due to the consumption of the Nip reactant and an increase at 300 nm associated with the formation of the Amf product ( Figure 3).…”

Silver nanoparticles stabilized by a polyaminocyclodextrin as catalysts for the reduction of nitroaromatic compounds

“…In this context, the use of NaBH 4 in the presence of noble metal nanoparticles (NPs) has attracted a certain interest [2,3]. The reduction of 4-nitrophenol or 4-nitroaniline (to 4-aminophenol and 1,4-diaminobenzene respectively) has been successfully carried out using NPs stabilized by various capping agents, including biopolymers such as dextran [4,5] or alginate [6][7][8], and PAMAM-or PPI-type dendrimers [3,9,10]. The latter class of auxiliaries is particularly interesting, because dendrimers provide a strictly defined micro-environment for the formation of the NP and for the actual nitroarene reduction process as well.…”

Trimethylchitosan-Capped Silver Nanoparticles with Positive Surface Charge: Their Catalytic Activity and Antibacterial Spectrum Including Multidrug-Resistant Strains of <em>Acinetobacter baumannii</em>

“…Using noble metal NPs as catalysts has become one of the model reactions for evaluating the catalytic activity of various metal nanoparticles capped with different stabilizers [39]. Although the reduction of 4-NP by NaBH4 is a thermodynamically feasible process, it is kinetically restricted in the …”