Sensing of Iron(III) Ion via Modulation of Redox Potential on Biliverdin Protected Silver Nanosurface

Abstract

Silver nanoparticle shows distinctive electrochemical properties, and it has a wide range of applications in most areas of science and technology. In the current work we reported the synthesis of biliverdin protected silver nanosurface (Ag-BV) that could sense Fe­(III) ion via reduction despite of their unfavorable reduction potential in aqueous medium. The addition of Fe­(III) to the Ag-BV suspension resulted an initial red shift in its surface plasmon resonance (SPR) band (420–450 nm) and a color change from straw yellow to deep brown due to the agglomeration of the nanoparticles. Subsequently a redox reaction caused the disappearance of the deep brown color and a significant blue shift occurred in its SPR band (up to 410 nm). The analysis further suggested that the aromatic π system of biliverdin (BV) on the Ag-BV nanosurface could make an electron carrier bridge that favors the transfer of an electron from atomic silver to an empty d orbital of Fe­(III) ion. The reduction of Fe­(III) ion resulted in oxidation of silver nanoparticles and loss of the nanostructure, which were evidenced in transmission electron microscopy analysis. Further investigation revealed that the partial charge on the iron center was ∼+1.16 in the Fe­(II)–biliverdin complex compared to ∼+1.26 in the Fe­(III)–biliverdin complex, suggesting a shift of electron density to the metal ion center. Thus, the biliverdin coated silver nanoparticle could be useful as a specific metal ion detector and a redox modulator for an Fe­(III)/Fe­(II) aqueous system. This might be the first report of its kind as the sensing mechanism involves an exceptional redox type phenomenon instead of mere coagulation of the nanoparticles in the presence of specific ions and produces a different color as an indicator for the ion detection.

Dissolved Organic Matter-Capped Silver Nanoparticles for Electrochemical Aggregation Sensing of Atrazine in Aqueous Systems

“…Because of their significant physicochemical features, AgNPs have been employed in enhancing the characteristics of many instruments such as catalysis, optical devices, electronic and electrochemical analysis. , These peculiarities make AgNPs a good candidate for many industrial, medical and environmental applications. − AgNPs have been used as an electrocatalyst for methanol electrooxidation and the reduction of 4-nitrophenol as well. In addition, they have been suggested for the removal of some reactive dyes, determination of antioxidant flavonols isomers, and improvement of the anode material for lithium-ion batteries .…”

Soluble Soybean Polysaccharide/Carrageenan Antibacterial Nanocomposite Films Containing Green Synthesized Silver Nanoparticles

“…Similar changes have also been observed by many researchers, which were ascribed to the increase in the size and yield of these particles. 22 Figure 1b shows the silver concentration of the AgNP colloidal dispersions measured by atomic absorption spectrometry. With the increase in the concentration of [Ag(NH 3 ) 2 ] + from 25 to 100 mM, the concentration of AgNPs in the SSPS-stabilized colloidal dispersions increased from 1.14 to 2.04 μg/mL (the concentration of free silver ions is <20 ng/mL).…”

Electrochemical Investigation of Porosity in Core–Shell Magnetoplasmonic Nanoparticles

“…The Ag core was oxidized or stripped at the potential E Ag , and the Fe 3 O 4 shell was also oxidized at the potential E Fe . The half reduction reaction of Ag is Ag + + e – → Ag, E 0 = 0.800 V, and that of Fe is Fe 3+ + e – → Fe 2+ , E 0 = 0.770 V vs standard hydrogen electrode (SHE) . That is, the reduction potential of the core is more positive than the shell.…”

“…The half reduction reaction of Ag is Ag + + e − → Ag, E 0 = 0.800 V, and that of Fe is Fe 3+ + e − → Fe 2+ , E 0 = 0.770 V vs standard hydrogen electrode (SHE). 25 That is, the reduction potential of the core is more positive than the shell. As a result, the first oxidation scan of the MagPlas core−shell exhibited a stripping peak for the shell.…”