Detection Limits For Fe3 Research Articles

Fruit waste-derived carbon dots with rhodamine B for the ratiometric detection of Fe3+ and Cu2.

A green and eco-friendly solvothermal approach is proposed for the synthesis of carbon quantum dots (CQDs) from watermelon rind. The as-prepared CQDs exhibited superior teal fluorescence in aqueous solutions, with a quantum yield of 13.9%. The CQDs and rhodamine B (RhB) were demonstrated to selectively react with Fe3+ and Cu2+, leading to a fluorescence (FL) quenching effect, which was successfully used for constructing "double-response-off" type ratiometric FL probes. A comparative study was conducted to assess the sensitivity and accuracy of ratiometric fluorescent probes, specifically those based on CQDs alone and in combination with RhB, for the selective detection of Fe3+ and Cu2+. By plotting the ratio of the differential fluorescence (ΔF) signals of CQDs to that of RhB against the practical application analyte concentration, the detection limits for Fe3+ (1.75 μM) and Cu2+ (0.43 μM) were markedly improved. The quenching mechanism was further explored, and the detection of Fe3+ and Cu2+ in surface water was demonstrated, showcasing the potential of efficient and effective nanosensors based on a static quenching effect. Futhermore, the addition of ascorbic acid can restore the fluorescence quenched by Fe3+. Therefore, in the presence of copper and iron, the ratiometric probe can demonstrate the ability to identify two different metals.

An Imidazo[1, 2-a]Pyridine Based Fluorescent Probe for the Continuous "on-off-on" Detection of Fe3+ and F.

An "on-off-on" fluorescent probe LK was synthesized from 2-benzoylpyridine and o-vanillin, which could sequentially detect Fe3+ and F- in DMSO/H2O solutions (v/v = 1/1, HEPES buffer, 1.0 mM, pH 7.0) with large Stokes shift (178nm). LK exhibited not only high selectivity and sensitivity towards Fe3+ and F-, but also strong anti-interference ability to other ions. LK was coordinated with Fe3+ at a ratio of 2:1, with a binding constant (Ka) of 1.3 × 104 M- 1. The detection limits for Fe3+ and F- were 6.9 × 10- 8 M and 3.0 × 10- 7 M, respectively. Due to its excellent sensing performance, LK was successfully applied in actual water samples and test papers for the detection of Fe3+ and F-.

The Monitoring and Cell Imaging of Fe3+ Using a Chromone-Based Fluorescence Probe.

A new structurally simple fluorescent CP probe based on chromone was designed and synthesized, and its structure was fully characterized using various analytical techniques. The CP probe displays a high selectivity and sensitivity for sensing Fe3+ with a "turn-off" fluorescence response over other metal ions in a DMSO/H2O (4:1, v/v) solution. The experiment results show that the CP probe is stable over a wide pH range of 2.0-12.0. The detection limit for Fe3+ was calculated to be 0.044 μmol•L-1. The molar ratio method indicated that the binding mode between the CP probe and Fe3+ is a 1:1 complex formation. HR-MS and density functional theory (DFT) calculations were also performed to further confirm the recognition mechanism. Both fluorescence imaging experiments and the MTT assay demonstrated that the CP probe was suitable for detecting intracellular Fe3+ and no significant cytotoxicity in living cells.

Bi-component sensing platform for the detection of Cd2+, Fe2+and Fe3+ ions.

The ability of N-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)isonicotinamide (naphydrazide) or 2,6-pyridinedicarboxylic acid (2,6-H2pdc) individually or as a bi-component system in distinguishing and detecting Fe3+ or Fe2+ and Cd2+ ions was investigated. The use of these molecules as single or bi-component analytes in absorption or emission spectroscopy studies showed that under specific conditions each had their own merits for specific purposes. UV-visible spectroscopic studies of 2,6-H2pdc for assessing the interactions with ferrous and ferric ions showed characteristic distinctions. The detection limit for Fe3+ analysed through UV-visible spectroscopy using naphydrazide was 0.46 μM, whereas it was 1.28 μM using 2,6-H2pdc. Naphydrazide together with Fe3+ allowed distinguishing Cd2+ ions from Zn2+ and Fe2+ ions. The bi-component system was useful for the selective detection of Cd2+ ions using fluorescence spectroscopy, with a detection limit for Cd2+ ions of 18.31 μM. The presence of Fe2+ and Cd2+ ions in a solution of the bi-component had resulted white-light emission. An analogous compound N,N'-(1,3,6,8-tetraoxobenzo[lmn][3,8]phenanthroline-2,7(1H,3H,6H,8H)-diyl)diisonicotinamide (binaphydrazide) was found unsuitable for such detections. Two 2,6-pyridinedicarboxylate Fe3+ complexes possessing protonated naphydrazide or binaphydrazide were prepared and characterised. These complexes were also found unsuitable for the detection of the said ions in solution. Electrochemical studies with the bi-component system showed that cyclic voltammograms could distinguish Fe3+ or Fe2+ from Cd2+ ions.

A novel fluorescent probe for the detection of Fe3+ ions with Eu3+/SnO2 nanocrystals Co-doped silica glasses

Detection of Fe3+ ions is of paramount importance for environmental protection and human health. Herein, we reported a highly selective and sensitive fluorescence probe for the quantification of Fe3+ ions in aqueous solution with Eu3+/SnO2 nanocrystals co-doped silica glasses as the sensing unit. Due to the high stability of silica glasses and their efficient protection for emitting centers, the probe has good recyclability and can be applied in real water environment, indicating its potential for on-site sensing. The detection limit of Fe3+ ions is 7.54 nmol/L. Experiments were carried out to verify that the probe shows excellent cross interference with other metal ions. The detecting mechanism can be ascribed to the excitation/emission absorption and energy transfer of Fe3+ ions. Our work paves a novel way of semiconductor oxide nanocrystals for applications in optoelectronics.

Carbon dots-embedded zinc-based metal-organic framework as an efficient fluorescent sensor for the detection of ferric and phosphate ions

Carbon dots were prepared from urea and sodium citrate using a microwave method which was combined with zinc nitrate and dimethylimidazole to prepare CDs@ZIF-8 composites using a one-pot method. It was used to develop a novel fluorescent sensor for the rapid and effective detection of Fe3+. Owing to intense contacts and electron transfer between CDs@ZIF-8 and Fe3+, the fluorescence was severely diminished. The burst fluorescence of the Fe3+ system was restored considerably due to a higher binding preference between Fe3+ and PO43-. Furthermore, the detection limit for Fe3+ was 5.2 μM. Our construction of a fluorescent sensor provides a simple and rapid platform for detecting Fe3+ and PO43- in human health and biodiversity.

Fluorescent probe based on acyclic cucurbituril to detect Fe3+ ions in living cells

Fe3+ is an essential element for human body, misregulation of which in cell are concerned with serious diseases. It is very meaningful to detect Fe3+ in living cells. Here, a novel fluorescent probe (Py-ACB) based on acyclic cucurbituril and pyrene was synthesized. Py-ACB exhibits high selectivity and sensitivity to Fe3+, Fe3+ is coordinated with the carbonyl groups and oxygen atoms of Py-ACB, resulting in reverse photo-induced electron transfer (reverse PET) from pyrene unit to the carbonyl oxygen atoms to induce fluorescence quenching. The binding constant and detection limits of Fe3+ recognized by Py-ACB are 9.26 × 104 M−1 and 2.51 × 10−8 M, respectively, and Py-ACB showed high response speed to Fe3+. More importantly, the probe Py-ACB showed strong fluorescence emission in living cell, which allowed the detection of Fe3+ in live cells by bioimaging.

Water soluble β-CD-PMAA/PMAm/PHEMA-Coumarin macromolecular fluorescent probes prepared via RAFT method and their sensing ability to Fe3+/Fe2+ and Cu2+ ions

Developing water-soluble fluorescent probes has important scientific and practical significance. In this work, coumarin derivatives bearing -OH were obtained through the classical Knoevenagel reaction firstly. Secondly, -CC- on allyl bromide was introduced into coumarin by Williamson ether formation method. Thirdly, hydrazine hydrate was added to the coumarin derivatives, a polymerizable small molecular coumarin fluorophore containing probe was obtained successfully. And, the -COOH on di-thioester underwent an esterification reaction with –OH groups on β-cyclodextrin(β-CD) to prepare oligomer based reversible addition-fragmentation chain transfer(RAFT) reagents. Finally, three copolymer probes β-CD-PMAA-Coumarin, β-CD-PMAm-Coumarin, and β-CD-PHEMA-Coumarin were prepared via RAFT polymerization, in which CC-coumarin was used as the functional monomer and methacrylamide(MAm)/methacrylic acid (MAA)/hydroxyethyl methacrylate (HEMA) as the main monomers. The MALDI-TOF mass tests showed that the macromolecular level probes were successfully prepared. These polymer probes have molecular weights up to 5.4 kDa and have narrow molecular weight distributions (PDI≤1.31). With the assistance of water-soluble long-chained PMAm/PMAA/PHEMA and hydrophilic β-CD, the coumarin containing macromolecular fluorescent probes could be dissolved in water readily. These water soluble polymer fluorescent probes could recognize Fe3+/Fe2+ and Cu2+ ions with high sensitivity. The detection limit of Fe3+ could be as low as 0.34 μM. This study successfully developed a promising technique for producing highly selective, fully water-soluble fluorescent macromolecular probes.

The efficient detection of Fe3+ by sulfonamidated lignin composite carbon quantum dots

AbstractFluorescent carbon quantum dots are a new type of nano‐fluorescent probe material, which overcomes some deficiencies of organic fluorescent materials and semiconductor quantum dots. In addition, they also have excellent optical properties, biocompatibility, and good application potential in environmental detection and other fields. To realize the special functions of carbon quantum dots, various functionalized composite carbon quantum dots have also been gradually developed. Lignin is a kind of natural polymer material rich in aromatic ring structure, which has abundant π electrons and a large number of easily functionalized active groups. Therefore, lignin is gradually used as a fluorescent probe material. In this article, sulfadiazine, p‐aminobenzenesulfonic acid, ammonium sulfamate as the amination reagents were used to modify lignin, and then citric acid was used as raw material to prepare carbon quantum dots (CQDs), and finally sulfadiazine lignin composite carbon quantum dots (PSA‐L‐CQDs), sulfamic acid lignin composite carbon quantum dots (BSA‐L‐CQDs), and sulfamate amine lignin composite carbon quantum dots (ASA‐L‐CQD) were prepared. Their structure and fluorescence characteristics were analyzed. The selectivity and sensitivity of PSA‐L‐CQDs to metal ions were tested by fluorescence spectroscopy. The experimental results show that PSA‐L‐CQDs have good selectivity and high sensitivity to Fe3+. The detection limit of Fe3+ was 29.5634 nmol/L. The composite carbon quantum dots have the advantages of low cost, simple manufacture, high selectivity, and high sensitivity.

Preparation of temperature-responsive nanomicelles with AIE property as fluorescence probe for detection of Fe3+ and Fe2+

Temperature-responsive nanomicelles with aggregation induced emission (AIE) property were prepared by the host–guest complexation of ferrocene functionalized tetraphenyl (TPE-Fc) and β-cyclodextrin-poly (N-isopropylacrylamide) (β-CD-(PNIPAM)7). The AIE chromophore TPE-Fc bound to the hydrophobic cavity of cyclodextrin serves as the core of micelles, and temperature sensitive PNIPAM serves as the shell to give the micelles good solubility. The size of the nanomicelles is about 100 nm. At the excitation wavelength of 340 nm, the strongest fluorescent emission peak was 421 nm. The introduction of cyclodextrin star polymer increased the fluorescence intensity of nanomicelles, thus improving the recognition of probe to Fe3+ and Fe2+. The fluorescent probe can quickly detect Fe3+ and Fe2+ in water within 5 min even in the presence of various interfering ions. The detection limits of Fe3+ and Fe2+ were 1.04 μM and 0.78 μM, respectively in the range of 10–90 μM. The formation of complex between the probe and Fe3+/Fe2+ was supported by Job’s plot. The probe was successfully applied to the detection of Fe3+and Fe2+ in actual water sample with a good recovery. In addition, a possible sensing mechanism for the interaction of iron ions with amide bond groups of nanomicelles was proposed.

Highly fluorescent nickel based metal organic framework for enhanced sensing of Fe3+ and Cr2O72− ions

Heavy metal contamination has sparked widespread concern among the populace. The significant issues necessitate the creation of high-performance fluorescent pigments that can identify harmful elements in water. The present study deals with metal organic framework [MOF] based on nickel [Ni-BDC MOF]. The Ni-BDC MOF was prepared by facile solvothermal method using nickel nitrate hexahydrate and terephthalic acid ligand as precursors. The MOF was characterized by various techniques in order to examine the crystal, morphological, structural, composition, thermal and optical properties. The detailed characterizations revealed that the synthesized Ni-BDC MOF are well-crystalline with high purity and possessing 3D rhombohedral microcrystals with rough surface. The MOF demonstrate good luminescence performance and excellent water stability. According to the Stern Volmer plot, the tests set up under optimized conditions demonstrate a linear correlation between the fluorescence intensity and concentration of both ions, i.e. Fe3+, and Cr2O72− ions. The linear range and detection limit for Fe3+ and Cr2O72− were found to be 0–1.4 nM and 0.159 nM, and 0–1 nM and 0.120 nM, respectively. The mechanisms for the selective detection of cations and anions were also explored. The recyclability for the prepared MOF was checked up to five cycles which showed excellent stability with just a slight reduction in efficiency. The constructed sensor was also used to assess the presence of Fe3+ and Cr2O72− ions in actual water samples. The results of the different experiments revealed that the prepared MOF is a good material for detecting Fe3+ and Cr2O72− ions.

Fabrication and DFT Calculation of Amine-Functionalized Metal-Organic Framework as a Turn-On Fluorescence Sensor for Fe3+ and Al3+ Ions.

Due to their important role in biological systems, it is urgent to develop a material that can rapidly and sensitively detect the concentration of Fe3+ and Al3+ ions. In this work, a brand-new CdII-based metal-organic framework [Cd(BTBD)2(AIC)]n (JXUST-18, BTBD = 4,7-bis(1H-1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole and H2AIC = 5-aminoisophthalic acid) with a 4-connected sql topology was designed and synthesized. The symmetrical CdII centers are linked by AIC2- ligands with μ3-η1:η1:η1:η1 coordination mode to form a [Cd2(COO)2] secondary building unit (SBU). The contiguous SBUs are further connected by BTBD ligands to form a two-dimensional (2D) layer structure. JXUST-18 can remain stable in aqueous solutions with pH values of 3-12 or in boiling water. Luminescent experiments suggest that JXUST-18 displays more than eightfold fluorescence enhancement in the presence of Fe3+ and Al3+ ions, and the detection limits for Fe3+ and Al3+ ions are 0.196 and 0.184 μM, respectively. Furthermore, the change in luminescence color is uncomplicatedly distinguishable with the naked eye under ultraviolet light at 365 nm. In addition, a series of devices based on JXUST-18 including fluorescence test strips, lamp beads, and composite films were developed to detect metal ions via visual changes in luminescence color. Significantly, JXUST-18 is a rare MOF-based turn-on fluorescence sensor for the detection of Fe3+ ions. The theoretical calculation suggests that the complexation of Fe3+/Al3+ ions and the -NH2 group contributes to fluorescence enhancement.

A novel optical fiber sensor based on AIEgens for highly selective and sensitive detection of Fe 3+

A novel optical fiber sensor for the detection of Fe3+ based on AIEgens was reported for the first time. A new anti-B18H22 derivative ((5-NH2C9H6N)2B18H20, Referred as to S1) bearing 5-aminoisoquinoline was synthesized via a one-pot and its structure was verified by 1H NMR and HRMS, photophysical properties were characterized by UV–Vis, fluorescence spectrum and theoretical calculation. The fluorophore exhibits obvious aggregation-induced emission enhancement (AIEE) characteristics in THF/H2O solution by increasing the aqueous concentration from 70% to 90%. The aggregation-induced emission (AIE) molecule in THF/H2O (ƒw = 90%) solution shows high selectivity for detecting Fe3+ over other metal ions by forming a 1:1 metal-to-ligand complex, and the detection limit is 5.25 × 10−5 M. The optical fiber sensor based on S1 for the detection of Fe3+ was fabricated, and the detection limit of Fe3+ can reach to be 0.137 nM. The sensor can be used to detect Fe3+ in chemical, environmental and biological fields.

Pseudo-Crown ether II: Intracellular and solution-, SiNPs based test-kits for ppm level detection of H2S gas

Perylene diimide based pseudo-Crown ether derivatives have been synthesized and characterized and their photophysical properties towards Fe3+ and H2S in 50% HEPES buffer–CH3CN and CH3CN solutions have been studied. PDI 1 showed formation of supramolecular aggregates with nanorods (dimer) morphology. Upon addition of Fe3+ ions, nanorods of PDI 1 transformed to spheres and PDI 1/2 showed a decrease in absorbance at (542 nm) and emission (578 nm) intensities supported by Job's plot, DLS, CV, WXRD and NMR techniques. The detection limits for Fe3+ are as low as 0.6 μM. We utilized PDI 1+Fe3+ complex as an ensemble for detection and discrimination of bio thiol derivatives. Upon addition of H2S (7.5 μM) and Cys (19 μM), the ensemble showed an increase at 542/578 nm (‘OFF-ON’) and further addition of H2S/Cys caused a decrease at same wavelength (‘ON-OFF’) with formation of new absorbance band at 630 nm (‘OFF-ON’). The mechanism of interaction of H2S involves reduction of Fe3+ to Fe2+ ions, followed by binding of HS− to form (PDI 1+Fe2++HS) complex. PDI 1 and PDI 1+Fe3+ complex has been successfully utilized for bioimaging of Fe3+ ions and H2S, respectively in live MG-63 cells. The solution and silica NPs based colorimetric test-kits were fabricated and detection of 30–60 ppm H2S gas has been achieved. These ‘OFF-ON-OFF’ and ‘ON-OFF-ON’ molecular switches mimic functioning of IMPLICATION, AND logic gates.

Using the extract of pomegranate peel as a natural indicator for colorimetric detection and simultaneous determination of Fe3+ and Fe2+ by partial least squares–artificial neural network

AbstractA simple, novel, biocompatible, and sensitive spectrophotometric method was developed for colorimetric detection and speciation of Fe3+ and Fe2+ ions. The method is based on the complex formation of Fe3+ and Fe2+ with organic constituents containing functional groups in pomegranate peel extract (PG). Developing of the color is specifically established in the presence of Fe3+ and Fe2+. Accordingly, in addition to direct detection of both cations, we carried out a quantitative multivariate model for their accurate determination in real matrix aqueous samples. Due to spectral interference, the simultaneous determination of Fe3+ and Fe2+ mixtures using spectrophotometry is a problematic issue. A combined multivariate as partial least squares (PLS)–artificial neural network (ANN) was used to create and adjust a model and predict said cations in test and real sample sets. In this context, the calibration model is based on absorption spectra in the 400–900 nm range for 98 different mixtures of Fe3+ and Fe2+. Calibration matrices contained 1–12 and 1–10 μg ml−1 of Fe3+ and Fe2+, respectively. The detection limits for Fe3+ and Fe2+ were 0.53 and 0.14 μg ml−1, respectively. The root mean square error of prediction (RMSEP) for Fe3+ and Fe2+ with PLS‐ANN was 0.78, 1.65 and 1.062, 0.894 in Kalugan waterfall and Tehran tap water. This strategy can simultaneously determine Fe3+ and Fe2+ in real matrix samples, and the reliability of the determination is acceptable.

Novel water soluble polymeric sensors for the sensitive and selective recognition of Fe3+/Fe2+ in aqueous media

Fe3+ and Fe2+ are common metal ions in natural water environments and creatures. The development of water-soluble fluorescent sensors for detecting Fe2+/Fe3+ ions was of great significance. In this work, two kinds of boron fluoride dipyrrole (BODIPY) fluorescent small-molecules were synthesized firstly. One of the small molecules contains a thioester bond that can be used as a chain transfer agent to participate in the polymerization process, and the other contains an unsaturated C = C double bond at the meso position. Through the reversible addition-fragmentation chain transfer polymerization (RAFT) polymerization method, methacrylic acid (MAA) and methacrylamide (MAM) were used as the main monomers, and small molecular fluorescent monomers were introduced to the end of the main chain. In this way, fluorescent macromolecules were obtained. The polymers were water soluble owing to the presence of long enough hydrophilic carboxyl and amide chains. These fluorescent probes exhibit high sensitivity to Fe2+/Fe3+, good selectivity, and anti-interference of other ions. The detection limit for Fe2+ was as low as 2.3 × 10−7 M, and the detection limit for Fe3+ can reach up to 4.5 × 10−7 M. The results show that these probes can be used as good sensors to identify Fe2+ and Fe3+. Moreover, the fluorophores could be incorporated into polymer chains as the RAFT reagents and/or functional monomers.

Construction of a new luminescent Cd(ii) compound for the detection of Fe3+ and treatment of Hepatitis B

Abstract A novel porous Cd(ii) metal–organic framework (MOF) with the chemical composition of {[H3O][Cd(bci)]} n ·2n(H2O) (1, H3bci = bis(2-carboxyethyl)isocyanurate) was prepared via hydrothermal responses of H3bci and Cd(NO3)2·4H2O. Luminescent property investigations indicated that compound 1 had high sensitivity toward Fe3+, and the detection limit of Fe3+ was as low as 2.15 × 10−4 M. The application values of Fe3+ on Hepatitis B were assessed, and its associated mechanism was identified simultaneously. First, the cytotoxic mediator (TNF-α) substance released into plasma was measured through the ELISA. In addition, real-time RT-PCR was employed to determine the Hepatitis B viral replication gene relative expression levels. Finally, the novel compound’s toxicity against human normal liver cells was tested by using the CCK-8 assay.

A phosphorus-doped g-C3N4 nanosheets as an efficient and sensitive fluorescent probe for Fe3+ detection

The phosphorus-doped carbon nitride nanosheets (P-g-C3N4 nanosheets) were prepared by ultrasonic stripping. Through the performance characterization, it was found that the P-g-C3N4 nanosheets emitted pure blue light with stable performance. Compared with other metal ions, it was found that the quenching reaction between P-g-C3N4 nanosheets and Fe3+ was the strongest. The detection limit of Fe3+ was found to be about 1.63 μM. P-doped g-C3N4 is expected to be an efficient fluorescent probe for Fe3+ detection.

An interpenetrated anionic In(III)-MOF for efficient adsorption/separation of organic dyes and selective sensing of Fe3+ ion and nitroaromatic compounds

A microporous indium-based metal-organic frameworks (MOFs), namely [(CH3)2NH2]2 [In2(H3L)2(OX)]·3DMF·2H2O (JOU-23) (H3L ​= ​terphenyl-3, 4′, 5-tricarboxylic acid; OX ​= ​oxalic acid), have been solvothermal synthesized and characterized. Single-crystal X-ray diffraction show that JOU-23 displays three-dimensional anionic framework with 2-fold interpenetrated nets and rare topology. Due to its anionic and porous framework, JOU-23 can be developed for effective absorbing and separating cationic organic dyes. Further studies reveal that both the charge and size of dye molecules would affect the dyes’ absorption and separation. In addition, JOU-23 dispersed in dimethyl formamide shows strong emission at about 364 ​nm. Thus, it was developed as an efficient fluorescent sensor for probing Fe3+ ions and nitroaromatic compounds. The detection limit of Fe3+ is as low as 2 ​× ​10−6 ​M (KSV ​= ​59,755 ​M−1), which is excellent in MOFs fluorescent probe. At the same time, JOU-23 shows widespread sensing performance to nitroaromatic compounds. Especially, the detection ability of JOU-23 for nitrobenzene (NB) is good. Although the NB concentration reaches only 4.175 ​× ​10−5 ​M, the quenching efficiency can achieve 86.4%. Further studies show that the quenching performance of JOU-23 is mainly attributed to the competition of excitation light absorption and the absorption of emission light by measured objects. These results indicate that JOU-23 can be applied as a multifunctional material for organic dyes adsorption/separation, Fe3+ ions detection, and nitroaromatic compounds sensing.

A dual-response fluoran-phenothiazine hybrid fluorescent probe for selective sensing of Fe3+ and ClO− and cell imaging application

Bifunctional fluorescent probes with dual-emission response attract extensive attention. A novel fluorescent probe FP, a hybrid of fluoran and phenothiazine, has been designed and synthesized for selective sensing of Fe3+ and ClO− with dual-emission changes, which involes mechanisms of Fe3+-promoted spirolactone ring opening and ClO−-induced oxidation of phenothiazine moiety, respectively. In addition, the detection limits for Fe3+ and ClO− were estimated to be 49.1 and 35.9 nM, respectively. Significantly, FP can be employed as an tracer for the detection of Fe3+ ions within living HeLa cells by fluorescence imaging.