An unusual “off-on” fluorescence sensor for iron(III) detection based on fluorescein–reduced graphene oxide functionalized with polyethyleneimine (original) (raw)
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Nanochemistry Research, 2016
A graphene oxide-terpyridine conjugate (GOTC) based colorimetric and fluorescent nano-chemosensor was synthesized. It showed high selectivity and sensitivity for Fe2+ and Fe3+ ions in neutral aqueous solution over other metal ions such as Li+, Na+, Ba2+, Ca2+, Al3+, Cd2+, Co2+, Cu2+, Hg2+, Mn2+, Ni2+, Pb2+, Zn2+, Cr3+ and Ag+. In absorption spectra, upon addition of Fe2+ or Fe3+, the sensor displayed a peak at 568 nm, by changing the color of the solution from light pink for GOTC to light magenta and deep magenta for Fe3+ and Fe2+, respectively. Also, the fluorescence studies revealed that, Fe2+, Fe3+ and Co2+ quench the emission of GOTC at 473 nm, while other metal ions do not quench the fluorescence of GOTC in solution. Colorimetric and fluorescence techniques could be used for detection of Fe2+ ion concentration at least about 6-10 μM in water solution. The sensing on test paper was also investigated for the naked-eye detection of Fe2+.
ACS Applied Materials & Interfaces, 2012
We have developed a new highly fluorescent graphene oxide (GO)/poly(vinyl alcohol) (PVA) hybrid (GO-PVA) in an acidic medium (pH 4). Fourier transform infrared (FTIR) spectra indicate the formation of hydrogen bonds between the hydroxy group of PVA and the hydroxy groups of GO. The hybrid is highly fluorescent, because of passivation by hydrogen bonding, as evident from Raman spectra. The quantum yields of GO-PVA hybrids are higher than that of GO. The fluorescent microscopic images of the hybrids exhibit a fibrillar morphology, and all of them emit highly intense green light. Field-emission scanning electron microscopy (FESEM) micrographs also show a fibrillar morphology, which is produced due to the supramolecular organization of GO-PVA complex. The highly fluorescent GO-PVA1 hybrid has been used as a fascinating tool for selective sensing of Au 3+ ions in aqueous media with a detectable limit of ∼275 ppb. The sensitivity of the Au 3+ ion (300 μM) in the presence of 600 μM concentrations of each ion (
2023
A sensitive and selective copper(II) fluorescence Schiff base chemical sensor receptor 1 (short for N,N′-bis (salicylidene)-o-phenylenediamine) has been prepared. The fluorescence of receptor 1 in pH 8.2 phosphate buffer solution can be dramatically quenched by Cu 2 þ , whereas it is nearly unaffected by other metal ions. Based on this, a sensitive and selective fluorescent quenching method for Cu 2 þ detection has been established. Under the optimum conditions, a good linear relation exists between the quenching efficiency (F 0 /F) and the concentration of Cu 2 þ in the range of 1.0 Â 10 À 7-2.5 Â 10 À 6 mol L À 1. The detection limit (3s) for Cu 2 þ determination is 2.0 Â 10 À 8 mol L À 1. The present method has been successfully used for quantification of Cu 2 þ in soybean milk powder. Furthermore, the fluorescence switch property of the system was explored, and the system might be applied for determination of glutathione and construction of molecular logic gate.
2020
Dye doped polymer films which are sensitive to Fe (III) ions have been developed for using in the aqueous medium. PVC films were obtained by spreading the cocktail mixture onto a mylar film used as a supporting material. PMMA films were prepared with solvent casting method. Cation responses were examined for two different polymer films. Emission bands were obtained at different concentrations of Fe (III) ions. Because polymer films had the highest response to them. The calibration graphics were plotted for emission values at different Fe (III) concentrations. Besides, interference effects of Cr (III) and Fe (II) ions to Fe (III) ions were studied. Additionally, regeneration studies were carried out to examine application properties of the dye doped polymer films developed as a sensor for Fe (III) cations.
Journal of Colloid and Interface Science, 2017
A glassy carbon electrode (GCE) modified by calixarene functionalized reduced graphene oxide (CA/RGO) has been fabricated and utilized in this study for simultaneous voltammetric detection of several metal ions, Fe(II), Cd(II) and Pb(II), in aqueous solution. The CA/RGO nanocomposite was characterized in surface and electrochemical properties using scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Raman spectroscopy and electrochemical impedance spectroscopy (EIS). The CA/RGO coating significantly improves the sensitivity of electrochemical responses and separation of heavy metals. The electrochemical oxidation of Fe(III), Cd(II), and Pb(II) was performed by square wave voltammetry (SWV). The metal ions, Fe(III), Cd(II), and Pb(II), gave a linear relationship with their concentrations at 1.0×10-10-1.0×10-8 M on the CA/RGO/GCE. The detection limits of the metal ions were found to be similar at 2.0×10-11 M. A good recovery was also obtained for practical use of the CA/RGO/GCE in pharmaceutical formulation.
Carbon, 2012
Superparamagnetic Fe 3 O 4 nanoparticles were anchored on reduced graphene oxide (RGO) nanosheets by co-precipitation of iron salts in the presence of different amounts of graphene oxide (GO). A pH dependent zeta potential and good aqueous dispersions were observed for the three hybrids of Fe 3 O 4 and RGO. The structure, morphology and microstructure of the hybrids were examined by X-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy. TEM images reveal lattice fringes (d 311 = 0.26 nm) of Fe 3 O 4 nanoparticles with clear stacked layers of RGO nanosheets. The textural properties including the pore size distribution and loading of Fe 3 O 4 nanoparticles to form Fe 3 O 4-RGO hybrids have been controlled by changing the concentration of GO. An observed maximum ($10 nm) in pore size distribution for the sample with 0.25 mg ml À1 of GO is different from that prepared using 1.0 mg ml À1 GO. The superparamagnetic behavior is also lost in the latter and it exhibits a ferrimagnetic nature. The electrochemical behavior of the hybrids towards chromium ion was assessed and a novel electrode system using cyclic voltammetry for the preparation of an electrochemical sensor platform is proposed. The textural properties seem to influence the electrochemical and magnetic behavior of the hybrids.
Electrochimica Acta, 2015
This study examines the synthesis and characterization of Fe 3 O 4 / reduced graphene oxide nanosheet composites (Fe 3 O 4 /RGO NSCs) with different morphology of Fe 3 O 4 and their application in the detection of lead (II). The Fe 3 O 4 /RGO NSCs were synthesized via a simple single-step hydrothermal process without the use of templates, with different percentage of RGO (1, 3 and 5%). X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy results confirmed the growth of Fe 3 O 4 in the presence of RGO. Electrochemical properties of the Fe 3 O 4 /RGO NSCs electrode were investigated by differential pulse voltammetry (DPV), cyclic voltammetry and electrochemical impedance spectroscopy. These observations confirmed that the optimum percentage of RGO for the fabrication of an electrochemical lead sensor is 3%. The DPV results show that the limit of detection, the limit of quantification (S/N = 3) and the sensitivity are estimated as 0.082 nM, 0.2776 nM and 0.0554 mA. cm À2 nM À1 , respectively, in the linear segment. Results from the reproducibility experiments show that the use of Fe 3 O 4 / 3%RGO NSCs is feasible for the quantitative detection of certain concentration ranges of Lead (II).
Biosensors & bioelectronics, 2015
The sensitive detection of heavy metal ions in the organism and aquatic ecosystem using nanosensors based on environment friendly and biocompatible materials still remains a challenge. A fluorescent turn-on nanosensor for lead (II) detection based on biocompatible graphene quantum dots and graphene oxide by employment of Pb(2+)-induced G-quadruplex formation was reported. Graphene quantum dots with high quantum yield, good biocompatibility were prepared and served as the fluorophore of Pb(2+) probe. Fluorescence turn-off of graphene quantum dots is easily achieved through efficient photoinduced electron transfer between graphene quantum dots and graphene oxide, and subsequent fluorescence turn-on process is due to the formation of G-quadraplex aptamer-Pb(2+) complex triggered by the addition of Pb(2+). This nanosensor can distinguish Pb(2+) ion from other ions with high sensitivity and good reproducibility. The detection method based on this nanosensor possesses a fast response time...
Spectroscopic investigations of graphene derivatives coated with nanostructured Fe3O4
Nanocomposites based on graphene oxide (GO)–iron oxide Fe3O4 and reduced GO (rGO)–Fe3O4 were synthesized by using a simple hydrothermal method, and their morphology and structure are investigated aiming to get an insight into on how the removal of oxygen group affects the dispersibility of Fe3O4 on GO layers. Transmission electron microscopy observations showed that nanostructured Fe3O4 with diameters of about 6–11 nm and lengths of 46–56 nm evenly spread over the GO/rGO sheets decorating their surface. The X-ray diffraction patterns prove the presence of the Fe3O4 on the surface of GO/ rGO nanosheets leading to their disaggregation in addition to an in situ reduction of GO. Fourier transform infrared and Raman spectroscopic studies provide evidence of donor–acceptor interaction between the Fe3O4 and GO/ rGO which can display additional functionalities of these heterostructures and thus will have great advantage for potential applications.