Adsorption and detection of Escherichia coli using an Au substrate modified with a catecholate-type artificial siderophore–Fe3+ complex

Abstract

A catecholate-type artificial siderophore with a terminal-NH2 group (1) and its Fe(3+) complex (2) were prepared. Siderophore 1 was characterized by (1)H NMR, FT-IR, and ESI-TOF MS spectroscopy. The corresponding Fe(3+) complex 2 was obtained by reaction of 1 with Fe(acac)3. The absorption band at 500 nm (ε = 4670 M(-1) cm(-1) at pH 7.0) of the electronic absorption spectrum of 2 is assignable as the LMCT (O(catecholate) → Fe(3+)) absorption band. This band indicates the formation of the Fe(3+) complex of 1. The biological activity of 2 with respect to Escherichia coli was clearly confirmed by observing that it permeates into the cell membrane. The self-assembled monolayer of 2 on an Au substrate, 2/Au, was prepared and its preparation was confirmed by FT-IR reflection-absorption spectroscopy (IR-RAS) and cyclic voltammetry (CV). Furthermore, a quartz crystal microbalance (QCM) chip modified with 2 effectively adsorbed E. coli. M. flavescens, an organism which is incapable of synthesizing siderophores and must therefore use exogenous hydroxamate-type siderophores for growth, did not adsorb on 2/Au. In contrast, E. coli did not adsorb on the hydroxamate-type artificial siderophore-Fe(3+) complex (3)-modified Au substrate, 3/Au. These results provide preliminary evidence that microbes recognized Fe(3+) ion-bound siderophores on the surface. The detection limit of 2/Au was ∼10(4) CFU mL(-1).

π-Plasmon absorption of carbon nanotubes for the selective and sensitive detection of Fe3+ ions

“… 40 Various natural and synthetic siderophores have been used for the selective and sensitive detection of Fe 3+ . 41 One of the most commonly used natural bacterial siderophores is deferoxamine (DFO) ( Scheme 1 ), which can form a very stable hexadentate iron chelate complex with a stability constant of about 10 31 M –1 . 42 , 43 The DFO siderophore changes its conformation upon binding with Fe 3+ ( Scheme 1 ).…”

Identification of a New Siderophore Acinetoamonabactin Produced by a Salt‐Tolerant Bacterium Acinetobacter Soli

“…have reported a series of artificial siderophores which contain terminal aminomethane unit and smartly utilized those to immobilize pathogens onto the modified gold electrode surfaces . Therefore, demonstrating the remarkable applications of the siderophores in the adsorption and detection of microbes on a chip modified with siderophores containing terminal NH 2 group . Furthermore, to confirm the presence of free NH 2 group in acinetoamonabaction, we added stoichiometric amount of salicyldehyde to the siderophore solution and performed HR‐MS (in the positive ion mode) of the solution mixture.…”

Iron(III) Complexes with Hybrid-Type Artificial Siderophores Containing Catecholate and Hydroxamate Sites

“…25091), a Gram-positive bacterium that has a hydroxamate-type siderophore transport system but cannot produce the siderophores by itself. Moreover, two types of the artificial siderophores ( H 6 L C3 and H 3 L H3 ) and their iron­(III) complexes, tris-catecholate (K 3 [ Fe III L C3 ]) and tris-hydroxamate type complexes ([ Fe III L H3 ]) with a tris­(3-aminopropyl)­methylamine anchor, respectively (Figure ), − were prepared, and the biological activity of the complexes against the microorganisms such as M. flavescens and Escherichia coli was evaluated.…”

“…Furthermore, the terminal amine groups in these artificial siderophore complexes could connect with other molecules via amide condensation. The siderophore–iron­(III) complex-modified Au substrates have also been prepared, demonstrating its sensing capability for the microorganisms. − …”