Fluorescent siderophore-based chemosensors: iron(III) quantitative determinations

Abstract

A highly sensitive and selective method is described for a rapid and easy determination of iron(III). This procedure is based on fluorimetric detection combined with the attractive properties of siderophores and biomimetic ligands, which are strong and selective ferric chelators. Azotobactin delta, a bacterial fluorescent siderophore, three fluorescent derivatives of desferriferrioxamine B with a linear structure (NBD-, MA-, NCP-desferriferrioxamine B) and one tripodal biomimetic ligand of desferriferrichrome carrying an anthracenyl fluorescent probe were examined. A very efficient static quenching mechanism by iron was observed for all the ligands considered in this work. Our results identify azotobactin delta as the most promising chemosensor of ferric traces in water, more sensitive than the NBD-desferriferrioxamine B fluorescent ligand. Under more lipophilic conditions, the anthryl-desferriferrichrome biomimetic analogue showed similar analytical potential and was found to be more sensitive than the lipophilic MA- and NCP-desferriferrioxamine B. Their detection limits were respectively 0.5 ng mL-1 for azotobactin delta and 0.6 ng mL-1 for the anthryl tripodal chelator. The calibration curves were linear over the range 0-95 ng mL-1 and 0-180 ng mL-1. Various foreign cations have been examined and only copper(II) and aluminium(III) were shown to interfere when present in similar concentrations as iron(III). The developed procedure using fluorescent siderophores or biomimetic ligands of iron(III) may be applied (1) to monitor iron-(III)-dependent biological systems and (2) to determine iron(III) quantitatively in natural waters and in biological systems.

The Pseudomonas aeruginosa Pyochelin-Iron Uptake Pathway and Its Metal Specificity

“…When loaded with Fe 3ϩ , this fluorescence is completely quenched (21). The presence of metals causes spectral variations of siderophores or synthetic chelators, and these variations are used to determine the kinetic and thermodynamic parameters of ligand-metal interactions (7,17,30,31). We used these properties to investigate whether Pch is able to chelate other metals more or less efficiently than it does Fe 3ϩ .…”

Siderophore-based detection of Fe(iii) and microbial pathogens

“…turn-off and a slight blue-shift in the wavelength of maximum absorption. 73 The quantum yield for azotobactin is 0.28 at pH 2 (6-hydroxypyrene-1,3,6-trisulfonic acid standard; Φ = 0.96, pH 2). 97 A fluorescence assay for Fe(III) determination using azotobactin δ provided a linear range between 0 -95 ng/mL Fe(III) and a detection limit of 0.5 ng/mL (89 nM; acetate buffer, pH 4.4).…”

“…We first consider fluorescent siderophores employed for Fe(III) sensing in solution. [73][74][75] Subsequently, we describe efforts to immobilize siderophores in materials, including micelle-templated silica and sol gel, for the optical detection of this metal ion. [76][77][78][79][80][81]83 Azotobactin δ 3 is a fluorescent siderophore produced by Azotobacter vinelandii and shares structural similarities with the pyoverdines.…”

“…9,[73][74][75][76][77][78][79][80][81][82][83] Next, we evaluate several synthetic fluorophore-siderophore conjugates where fluorophores are attached to native siderophore scaffolds to provide fluorescence responses following Fe(III) coordination. [84][85][86][87][88] Iron is a paramagnetic metal ion and thus has a propensity to quench fluorophore emission.…”

Compostos de ferro de interesse farmacológico: avaliação da estabilidade, toxicidade em organismos aquáticos, transporte em células e capacidade de gerar reservatórios de ferro lábil

“…Outros sideróforos naturais ou sintéticos, diferentes do DFO, podem ser acoplados a sondas fluorescentes ou tornados intrinsicamente fluorescentes na busca de sintetizar novas sondas fluorescentes específicos de ferro 83,[86][87][88][89][90] …”