Multi-tasking Schiff base ligand: a new concept of AuNPs synthesis

Abstract

Multi-tasking 3,4-dihydroxysalophen Schiff base tetradentate ligand (3,4-DHS) as reductant, stabilizer, and catalyst in a new concept of gold nanoparticles (AuNPs) synthesis is demonstrated. 3,4-DHS is able to reduce HAuCl4 in water, acting also as capping agent for the generation of stable colloidal suspensions of Schiff base ligand-AuNPs assemblies of controlled size by providing a robust coating to AuNPs, within a unique reaction step. Once deposited on carbon electrodes, 3,4-DHS-AuNPs assemblies show a potent electrocatalytic effect towards hydrazine oxidation and hydrogen peroxide oxidation/reduction.

Reagent-Less and Robust Biosensor for Direct Determination of Lactate in Food Samples

“…In a previous work, we reported the multi-tasking N , N ′-Bis(3,4-dihydroxybenzylidene)-1,2-diaminobenzene Schiff base tetradentate ligand (3,4DHS) as reductant, stabilizer, and catalyst in a new concept of AuNPs synthesis. Once these assemblies were deposited on screen-printed carbon electrodes, the resulting nanostructured platforms exhibited excellent electrocatalytic activity towards the oxidation and the reduction of peroxide in alkaline medium [ 34 ]. In this work, we have gone a step further and have used these platforms to build a portable lactate biosensor based on lactate oxidase in which the lactate is oxidized to pyruvate and hydrogen peroxide in presence of oxygen.…”

“…3,4DHS–AuNPs were synthesized as previously reported [ 34 ] by mixing aqueous HAuCl 4 with 3,4DHS solution, and chemical reduction was left to proceed for 24 h at room temperature. The 3,4DHS capped AuNPs thus formed were separated by centrifugation at 9000 rpm (7700 g) and washed with water to remove excess 3,4DHS.…”

“…The size and concentration of 3,4DHS–AuNPs were estimated from the ratio of absorbance measured at the surface plasmon band (~520 nm) and the absorbance at 450 nm, as described by Haiss et al [ 36 ]. The particle size value was confirmed by transmission electron microscopy [ 34 ]. Thus, a stock solution of 17.7 nM (33 ± 3 nm) 3,4DHS–AuNPs was employed.…”

“…Recently, we reported the use of a multi-tasking N , N ′-Bis(3,4-dihydroxybenzylidene) -1,2-diaminobenzene Schiff base tetradentate ligand (3,4DHS) as reductant, stabilizer, and catalyst in a new concept of gold nanoparticles (AuNPs) synthesis [ 34 ]. This ligand contains the quinone/hydroquinone functional group and is capable of reducing HAuCl 4 in water, also acting as a capping agent for the generation of stable colloidal suspensions of Schiff base ligand–AuNPs assemblies of controlled size by providing a robust coating to AuNPs within a unique reaction step.…”

“…This ligand contains the quinone/hydroquinone functional group and is capable of reducing HAuCl 4 in water, also acting as a capping agent for the generation of stable colloidal suspensions of Schiff base ligand–AuNPs assemblies of controlled size by providing a robust coating to AuNPs within a unique reaction step. These 3,4DHS–AuNPs assemblies—deposited on carbon electrodes—show a potent electrocatalytic effect towards hydrazine oxidation and hydrogen peroxide oxidation/reduction [ 34 ]. Following these previous studies, the present work takes the preparation of 3,4DHS–AuNPs assemblies one-step further by using them for the construction of a new l -lactate biosensor.…”