Detection Of Ferric Ions Research Articles

微波法制备掺氮碳点及其用作探针检测铁离子

微波法制备掺氮碳点及其用作探针检测铁离子

Electrochemical synthesis of multicolor fluorescent N-doped graphene quantum dots as a ferric ion sensor and their application in bioimaging.

A novel electrochemical strategy for simple and facile synthesis of semicarbazide functionalized nitrogen-doped graphene quantum dots (N-GQDs) was reported, based on direct exfoliation and oxidation from graphite rods. The average diameter of the as-synthesized N-GQDs is about 20 nm, and their dispersion is bright yellow due to the rich nitrogen and oxygen functional groups on their surface. The N-GQD dispersion was further applied in the selective detection of ferric ions (Fe3+) based on the photoluminescence (PL) quenching of N-GQDs after adding Fe3+. The fluorescent sensor has a wide linear range of 0-200 μM and a detection limit of 0.87 μM, which is much lower than the maximum level (0.3 mg L-1, equivalent to 5.4 μM) of Fe3+ permitted in drinking water by the U.S. Environmental Protection Agency (EPA). Moreover, these novel N-GQDs exhibit much wider emission bands, which extend into the entire visible region, and emit three primary color fluorescence independently. This distinctive behavior of the as-prepared GQDs not only breaks the limitation that traditional reported GQDs only exhibit blue emission in the short-wavelength region, but may also provide a new research platform for further applications of GQDs in real environmental detection and biological imaging systems.

Copper-based metal–organic framework nanoparticles for sensitive fluorescence detection of ferric ions

A luminescent amino-functionalized metal–organic framework (Cu–MOFs) was synthesized from 2-aminoterephthalic acid and Cu(ii) ions by a solvothermal method.

Ultrasensitive fluorometric determination of iron(iii) and inositol hexaphosphate in cancerous and bacterial cells by using carbon dots with bright yellow fluorescence.

An ON-OFF-ON dual-function fluorescent nanoprobe is described for the trace detection of ferric ions and inositol hexaphosphate (IP6) in living cells. It is based on the use of yellow-fluorescent nitrogen-doped carbon dots (YN-CDs). Highly fluorescent YN-CDs were synthesized by a hydrothermal process. They have an absolute quantum yield of 2.15% and excitation/emission peaks at 420/575 nm. Fluorescence is quenched by Fe3+via photo-induced electron transfer. The quenchometric assay has a 34 nM detection limit for Fe(iii). On addition of IP6 which has a high affinity for Fe3+ due to the formation of Fe-O-P bonds, fluorescence becomes gradually restored. The resulting ON-OFF-ON assays for Fe(iii) and IP6 are reliable and sensitive. IP6 can be detected at concentrations as low as 2 nM. The nanoprobe was then applied to the determination of Fe3+ and IP6 in living cells in a food matrix. Furthermore, YN-CDs exhibited excellent biocompatibility. Hence, the probe can be applied as a fluorescent ink for bioimaging, both in vitro (cancer cells and bacteria) and in vivo (nematodes and mice).

Fish-scale-derived carbon dots as efficient fluorescent nanoprobes for detection of ferric ions.

Herein, highly fluorescent carbon dots (CDs) with the incorporation of N and O functionalities were prepared through a facile and cost-effective hydrothermal reaction using fish scales of the crucian carp as the precursor. The as-prepared CDs exhibit strong fluorescent emissions at 430 nm with a relative quantum yield of 6.9%, low cytotoxicity, and robust fluorescence stability against photobleaching and good ionic strength. More significantly, the fluorescence of these CDs can be effectively and selectively quenched by Fe3+ ions, which enables the application of CDs as fluorescent Fe3+ nanoprobes with a linear range of 1–78 μmol L−1 and a detection limit of 0.54 μmol L−1. The proposed fluorescent CD nanoprobes can also be used for the assay of spiked Fe3+ in real water samples and human serums with high recoveries and low standard deviations. Hence, CDs can be potentially applied as safe and reliable fluorescent nanoprobes for environmental and clinical Fe3+ analyses.

A facile synthesis of label-free carbon dots with unique selectivity-tunable characteristics for ferric ion detection and cellular imaging applications

The application of a pH-tuning concept to create specific analytical responses of carbon dots towards a specific targeted metal ion.

Phosphorus and chlorine co-doped carbon dots with strong photoluminescence as a fluorescent probe for ferric ions.

Usually, carbon dots (CDs) display a relatively weak fluorescence quantum yield (QY). In order to obtain brighter CDs, phosphorus and chlorine co-doped CDs (P,Cl-CDs) were prepared via hydrothermal treatment of maltose in the presence of phosphoric and hydrochloric acids. The new CDs are highly monodispersed in water solution, have high fractions of P (14.4 atomic%) and Cl (8.9 atomic%), and exhibited yellow fluorescence with a QY of 15%. This is higher than that of monoatomic doped CDs (8.7 and 9.3% for P-CDs and Cl-CDs, respectively). The P,Cl-CDs are highly photostable, and fluorescence is strongly (statically) quenched by Fe(III). Fluorescence decreases with increasing concentration of Fe(III) in the range from 0.1-8.0μmol⋅L-1, with a 60nmol⋅L-1 detection limit. The doped CDs are shown to be a viable nanoprobe for the fluorometric determination of Fe(III) in spiked serum and water samples. Graphical abstract Schematic presentation of one-step synthesis of phosphorus and chlorine co-doped carbon dots with high photoluminescence for the detection of ferric ions.

Silica-embedded CdTe quantum dots functionalized with rhodamine derivative for instant visual detection of ferric ions in aqueous media

A novel hydrophilic ratiometric fluorescence sensor for instant visual detection of Fe3+ was successfully prepared by integrating silica-embedded CdTe quantum dots (QDs) with rhodamine derivative. The rich hydrophilic group and large specific surface area of CdTe@SiO2 QDs favored the adsorption of rhodamine derivative on silica and improvement of its water solubility. The results proved that the ratiometric fluorescence sensor shows a much higher selectivity towards Fe3+ with the detection limit as low as 26.5 nM than other typical cations and anions in aqueous solution. Moreover, the fluorescence response occurs instantaneously and reaches stability less than one second. Additionally, a simple and rapid paper-based analytical device was designed for on-site and visual detection of Fe3+ in actual water samples. Hence, this study provided a good candidate for the on-site and visual sensing of Fe3+ in the environmental analysis.

Environmentally benign conversion of waste polyethylene terephthalate to fluorescent carbon dots for “on-off-on” sensing of ferric and pyrophosphate ions

The increasing production of waste polyethylene terephthalate (PET) is a growing problem worldwide. Environmentally benign conversion of waste PET to valuable materials remains a substantial challenge. In this paper, we developed a green route to reuse waste PET for low-cost synthesis of fluorescent carbon dots (CDs) via air oxidation followed by hydrothermal treatment in aqueous H2O2 solution. No expensive, corrosive, or toxic reagents, or severe conditions were required in the synthetic process. The resultant CDs possessed abundant oxygenous groups and unique photoluminescence (PL) properties, which showed a highly selective and sensitive detection of ferric ion (Fe3+) through a PL quenching effect (on-off). The fluorescence of CDs quenched by Fe3+ could be restored specifically with pyrophosphate anion (PPi), rendering the CDs/Fe3+ sensor promising for PPi detection (off-on). The linear ranges for Fe3+ and PPi detections were 0.5–400 and 2–600 μM, and the limit of detections (LODs) were 0.21 and 0.86 μM, respectively. The sensing system applied for Fe3+ and PPi assays in real water samples and human urine achieved good results. After detailed investigations, a possible electron transfer process was proposed for explaining the “on-off-on” sensing mechanism.

Intermolecular hydrogen bonding-mediated synthesis of high-quality photoluminescent carbon dots for label-free fluorometric detection of Fe3+ ions

Hydrogen bonding interactions guided supramolecular self-assembly has been widely studied, which played important roles in the field of nanotechnology and nanodevices. Herein, an effective intermolecular hydrogen bonding mediated heating-up synthesis of high-quality fluorescent carbon dots (CDs) is developed based on hydrogen-bonding between trimesic acid and urea. Upon optimizing the hydrogen-bonding interaction, high quality of CDs with high monodispersity and stability could be obtained. Besides, these CDs could be used for sensitive and specific detection of ferric ions. The novel strategy may pave a new way in molecular engineering for the fabrication of high quality of CDs.

Highly fluorescent N-doped carbon nanodots as an effective multi-probe quenching system for the determination of nitrite, nitrate and ferric ions in food matrices

Tris-(hydroxymethyl)-aminomethane and urea were used as low-cost precursor compounds to synthesize highly fluorescent N-doped carbon nanodots (CNDs), in an environmentally-friendly, inexpensive process. The as-prepared CNDs exhibit blue fluorescence, excellent photostability under various conditions, water dispersibility and stability over several parameters, such as a wide range of pH. The N-doped CNDs were applied as a multi-probe fluorescence quenching system to the sensitive detection of nitrite (NO2−), nitrate (NO3−) and ferric (Fe3+) ions in food matrices. The recoveries from spiked food samples were fairly acceptable without significant interferences despite the complexity of the tested matrices. The decrease in fluorescence intensity is in linear relationship with the concentrations of NO2−, NO3− and Fe3+, in the ranges of 0.015–1.11 mM, 0.072–0.60 mM and 2.9–176 μΜ, respectively. The as-synthesized carbon dots were used for the detection of NO2−, NO3− and Fe3+ in food matrices after proper pretreatment, concluding that the multi-probe fluorescence system may potentially be implemented in food control. The FRET mechanism is able to describe the quenching of the CNDs-NO2− system, while the proportional temperature-dependent relationship with the slopes of calibration plots hint at a dynamic quenching mechanism. In the case of the CNDs-Fe3+ system, the slopes exhibit an inverse temperature dependence, indicating a static mechanism while there is no indication of a FRET mechanism.

PH-dependent selective ion exchange based on (ethylenediamintetraacetic acid-nickel)-layered double hydroxide to catalyze the polymerization of aniline for detection of Cu2+ and Fe3+

A pH-dependent selective ion exchange coupled with catalytic polymerization of aniline has been developed for sensitive detection of copper (Cu2+) and ferric ions (Fe3+). Ethylenediamintetraacetic acid (EDTA) chelated with nickel ion (Ni2+) were intercalated in a layered double hydroxide via a co-precipitation reaction. The product was subsequently applied as sorbent for the enrichment of Cu2+ at pH 6.5 and Fe3+ at pH 4.5. Since both Cu2+ and Fe3+ have stronger complex formation constants with EDTA, Ni2+ exchanges with Cu2+/Fe3+ selectively. The resulting sorbent containing Cu2+/Fe3+ was transferred to catalyze the aniline polymerization reaction, since Cu2+/Fe3+ could be released by the sorbent effectively at different pH values and have high catalytic abilities for the polymerization reaction. The resulting polyaniline with different colors were produced at different pH values, an observation that was utilized to distinguish between the colorimetric signals of Cu2+ and Fe3+. The extraction temperature, extraction time, catalysis time and pH were optimized. The results showed that this method provided low limits of detection of 0.1 nM (6.4 ng/L) for Cu2+, 1 nM (56 ng/L) for Fe3+, wide linear ranges (0.0005–2.5 µM, and 0.005–5 µM, respectively), and good linearities (r2 values of 0.9904, and 0.9965, respectively). The optimized method was applied to river water samples. Using Cu2+/Fe3+ as examples, this work provided a new and interesting approach for the convenient and efficient detection of metal ions in aqueous samples.

An unusual (3,10)-coordinated 3D network coordination polymer as a potential luminescent sensor for detection of nitroaromatics and ferric ion

A cadmium coordination polymer {[Cd3(itp)2(btc)2]·4H2O}n (1) (itp = 1-imidazol-1-yl-3-(1,2,4-triazol-4-yl)propane, btc = 1,3,5-benzenetricarboxylate) was synthesized and characterized. 1 shows an unusual (3,10)-coordinated 3D network based on the [Cd3(COO)4] trimeric clusters. 1 is a good luminescence sensor for detection of nitrophenol nitroaromatics TNP, 2,4-DNP, 4-NP, ANP and 2-NP, especially for TNP. 1 also exhibits high sensitive and selective luminescence sensor for detection of Fe3+ even in the presence of the competing ions. These selective luminescence quenching phenomena are mainly attributed to the energy-transfer quenching mechanism. 1 is a good luminescence sensor for detection of nitrophenol nitroaromatics and Fe3+. The detection limits of TNP, ANP and Fe3+ are 0.12 μM, 0.71 μM and 0.12 μM, respectively.

Rational synthesis of a luminescent uncommon (3,4,6)-c connected Zn(ii) MOF: a dual channel sensor for the detection of nitroaromatics and ferric ions.

The articulate combination of intriguing functional groups and luminescence properties can deliver metal-organic frameworks (MOFs) with multifarious applications viz. selective and specific sensing of nitroaromatic compounds (NACs), an important constituent of explosives, as well as sensing of toxic metal ions. In this regard, a new d10 configuration based Zn(ii) metal-organic framework (MOF) {(NH2(CH3)2)[Zn4(ddn)2(COO)(H2O)4]·solvent}n (1) has been synthesized using a π-conjugated and rigid multicarboxylate ligand 3,5-di(3,5-dicarboxylphenyl)nitrobenzene (H4ddn). 1 displays a 3D (3,4,6)-c connected net which is based on two types of binuclear [Zn2(μ2-COO)2(μ1-COO)2] and [Zn2(μ2-COO)4] clusters. Sensing studies of 1 to detect nitro-aromatic compounds reveal highly specific detection of 2,4-dinitophenol (DNP) with remarkable quenching (KSV = 8.93 × 103 M-1) and a low limit of detection (LOD: 1.12 ppm). The luminescence quenching mechanism in the case of 1 in the presence of NACs has been ascribed to the concurrent presence of the charge transfer as well as the weak interaction between the MOF and NACs. The activated framework of 1 also displayed highly selective detection of ferric ions with KSV = 1.13 × 104 M-1 with a low limit of detection (LOD: 1.24 ppm).

The utilization of a stable 2D bilayer MOF for simultaneous study of luminescent and photocatalytic properties: experimental studies and theoretical analysis.

A new Pb(ii)-based 2D MOF comprising π-conjugated ligand 4′-(1H-tetrazol-5-yl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (TZBPDC) and having the formula {[PbNa(TZBPDC)](H2O)(DMF)2}n (1) has been synthesized. Structural characterization of 1 indicates that the MOF has a 4-connected (4,4) motif. The photoluminescent investigation indicates that 1 can behave as potential luminescent sensor for the detection of nitroaromatic compounds (NACs), especially 2,4-dinitrophenol (2,4-DNP) and ferric ions, through the decrease in its luminescence intensity. Additionally, 1 also displays excellent capacity for the photodegradation of methylene orange (MO), which is a constituent of wastewater discharge. The most plausible mechanisms for the decrease in the luminescent intensity of 1 in the presence of different NACs have been explored though theoretical calculations, and the photocatalysis of 1 for organic dyes has been addressed using density of states (DOS) and partial DOS calculations.

A fluorometric and colorimetric dual-mode sensor based on nitrogen and iron co-doped graphene quantum dots for detection of ferric ions in biological fluids and cellular imaging

A dual-mode sensing strategy based on N, Fe-GQDs for effective and selective detecting of Fe3+ and cellular imaging was developed.

Nanospace-confined preparation of uniform nitrogen-doped graphene quantum dots for highly selective fluorescence dual-function determination of Fe3+ and ascorbic acid.

N-Doped graphene quantum dots (N-GQDs) combine the advantages of N-doped carbon and quantum dot materials, displaying enhanced performance in electrocatalysis, drug delivery, sensing and so on. In this work, novel hydrotropic N-GQDs with controlled size are obtained for the first time via a nanospace-confined preparation strategy, in which HNO3 vapour serves as scissors for quickly cutting the N-doped carbon nanolayer in the confined nanospace of reusable mesoporous molecular sieves. The as-prepared N-GQDs exhibit a uniform lateral size of about 2.4 nm, high photostability and yellow fluorescence, which is strongly quenched upon addition of ferric ions due to the coordination between ferric ions and N/O-rich groups of the N-GQDs surface. Significantly, the fluorescence response to Fe3+ is linear in the 0.5 to 40 μM concentration range and the N-GQDs showed good selectivity and satisfying recovery for ferric ion detection in tap water. Noteworthily, the quenched fluorescence by Fe3+ can be recovered by adding ascorbic acid (AA), which efficiently destroyed the coordination between Fe3+ and N-GQDs. Based on this principle, the N-GQDs were used to successfully construct an AA sensor, exhibiting a wide linearity range (between 0.5 and 90 μM) with a low detection of limit (80 nM at S/N = 3) and better selectivity towards AA compared with other common physiological substances. Finally, the constructed fluorescence sensor was employed successfully for AA determination in fish blood with satisfactory recovery ranging from 95.3 to 106.2%. The results indicate that N-GQDs synthesized by the nanospace-confined strategy are promising in biosensor fabrication.

A novel fluorescent and colorimetric probe for cascade selective detection of Fe(III) and pyrophosphate based on a click generated cyclic steroid–rhodamine conjugate

A novel fluorescent and colorimetric probe containing deoxycholic acid and rhodamine moieties was developed by click chemistry, and its cascade selective detection of ferric ion (Fe3+) and pyrophosphate (PPi) was investigated in details by spectral measurements. The probe displayed turn-on orange fluorescence and colorless to pink color change upon binding with Fe3+ by reversibly forming the metal complex and opening the spirolactam ring of rhodamine. Through a tandem ligand exchange, PPi with higher affinity for Fe3+ removed the metal from the complex and restored the spectral signal of the probe. The experimental results suggested that this novel molecule could serve as an efficient and economical dual signal chemosensing system for cascade bi-target analysis of Fe3+ and PPi with high selectivity, low detection limits and fast response time. Notably, this bi-functional probe also showed excellent performances in monitoring Fe3+ and PPi on silica gel plates, in water samples and living cells.

Degradation of ciprofloxacin using Fenton's oxidation: Effect of operating parameters, identification of oxidized by-products and toxicity assessment

Ciprofloxacin (CPX), a fluoroquinolone antibiotic, is found in the bulk effluents emerged from pharmaceutical industries. Its presence in the effluent may lead to toxicity to the aquatic life and antimicrobial resistance. Hence, the oxidative degradation of CPX by classical Fenton's process was investigated for the present study. The maximum CPX and total organic carbon (TOC) removal from the synthetic wastewater (initial CPX concentration = 100 mg L−1) were 70% and 55%, respectively, under the best reaction conditions ([H2O2]:[Fe2+] = 10, stoichiometric H2O2 concentration = 14.2 mM and initial wastewater pH = 3.0). Five major degradation products could be identified by high resolution liquid chromatography–mass spectrometry (HR LC-MS) which could have resulted by the occurrence of decarboxylation, defluorination, hydroxylation and cleavage of the piperazine ring. The time based detection of ferrous and ferric ions in aqueous phase confirmed the CPX degradation by hydroxyl radicals. A pathway has been proposed for CPX degradation by Fenton's process based on the kinetic decay and/or evolution profiles of CPX and intermediates as well as the release of inorganic ions into the aqueous solution. It was indicated from the rapid respirometric test that the wastewater toxicity was lowered after Fenton's treatment.

One-Step Synthesis of Fluorescent Boron Nitride Quantum Dots via a Hydrothermal Strategy Using Melamine as Nitrogen Source for the Detection of Ferric Ions

A facile and effective approach for the preparation of functionalized born nitride quantum dots (BNQDs) with blue fluorescence was explored by the hydrothermal treatment of the mixture of boric acid and melamine at 200 °C for 15 h. The as-prepared BNQDs were characterized by transmission electron microscopy (TEM), high-resolution TEM, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The single layered BNQDs with the average size of 3 nm showed a blue light emission under the illumination of the UV light. The BNQDs could be easily dispersed in an aqueous medium and applied as fluorescent probes for selective detection of Fe3+ with remarkable selectivity and sensitivity (the lowest detection limit was 0.3 μM). The fluorescence fiber imaging demonstrated that the as-prepared quantum dots could be used as a valuable fluorchrome. Therefore, the BNQDs could be envisioned for potential applications in many fields such as biocompatible staining, fluorescent probes, and biological labeling.