μM For Fe3 Research Articles

Reuse of waste Myrica rubra for green synthesis of nitrogen-doped carbon dots as an “on-off-on” fluorescent probe for Fe3+ and ascorbic acid detection

As one kind of high nutrition fruits, abandoned Myrica rubra causes great waste due to short storage period. For resource utilization, we herein fabricated the Myrica rubra-based N-doped carbon dots (MN-CDs) by a facile/green hydrothermal method. MN-CDs, fabricated from four regions of China, displayed significant differences in their corresponding fluorescence intensities (FIs). Interestingly, different batches of waxberry samples from the same region (Wenzhou, China) exhibited slight differences in their FIs, and also an excellent anti-photobleaching and anti-salt capacity. Based on Fe3+-triggered quenching effect and fluorescent recovery by redox reaction of AA and Fe3+, MN-CDs were employed to construct an “on-off-on” switch probe for sequential detection of Fe3+ and ascorbic acid (AA). Through Zeta potential, UV spectrum, Stern-Volmer equation, and valence-conduction band theory, the Fe3+-triggered quenching belonged to a static quenching process, which resulted from the synergistic contribution of inner filtering effect and photo-induced electron transfer mechanisms. The linear ranges for Fe3+ and AA detections were 1–1000 and 0.1–1000 mM. The limits of detection were 0.3 μM for Fe3+ in environmental waters, and 0.03 μM for AA in pharmaceutical tablets and fruit juice samples. Under 365-nm UV lamp, the color changes of test papers were easily observed from dark blue and bright blue in the presence of Fe3+ and AA, and thus the MN-CDs-based switch probe could be satisfactorily used for visually qualitative detection of Fe3+ and AA outdoor with our naked eyes. To sum up, MN-CDs not only realize resource reutilization of abandoned Myrica rubra, but also offer an convenient outdoor approach for qualitative detection of Fe3+ and AA in complex matrices.

A Cd(II) Luminescent Coordination Grid as a Multiresponsive Fluorescence Sensor for Cr(VI) Oxyanions and Cr(III), Fe(III), and Al(III) in Aqueous Medium.

Hydro(solvo)thermal reactions of Cd(NO3)2, N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide (NI-mbpy-34), and 5-bromobenzene-1,3-dicarboxylic acid (Br-1,3-H2bdc) afforded a luminescent coordination polymer, {[Cd(Br-1,3-bdc)(NI-mbpy-34)(H2O)]∙2H2O}n (1). Single-crystal X-ray diffraction analysis showed that 1 features a two-dimensional (2-D) gridlike sql layer with the point symbol of (44·62), where the Cd(II) center adopts a {CdO5N2} pentagonal bipyramidal geometry. Thermogravimetric (TG) analysis confirmed the thermal stability of 1 up to about 340 °C, whereas XRPD patterns proved the maintenance of crystallinity and framework integrity of 1 in CH2Cl2, H2O, CH3OH, and toluene. Photoluminescence studies indicated that 1 displayed intense blue fluorescence emissions in both solid-state and H2O suspension-phase. Owing to the good fluorescent properties, 1 could serve as an excellent turn-off fluorescence sensor for selective and sensitive Cr(VI) detection in water, with LOD = 15.15 μM for CrO42− and 14.91 μM for Cr2O72−, through energy competition absorption mechanism. In addition, 1 could also sensitively detect Cr3+, Fe3+, and Al3+ ions in aqueous medium via fluorescence-enhancement responses, with LOD = 2.81 μM for Cr3+, 3.82 μM for Fe3+, and 3.37 μM for Al3+, mainly through an absorbance-caused enhancement (ACE) mechanism.

Bimetallic Ag/Zn-ZIF-8: An efficient and sensitive probe for Fe3+ and Cu2+ detection

In this work, a series of bimetallic Ag/Zn-ZIF-8 materials were successfully developed for sensing toward traces of Fe3+ and Cu2+. The bimetallic Ag/Zn-ZIF-8 was synthesized via a one-pot method. Interestingly, this obtained bimetal Ag/Zn-ZIF-8 exhibited high photoluminescence property and excellent fluorescence quenching response to target analytes with high selectivity, sensitivity and detection limits of 3.9 μM for Fe3+, 6.7 μM for Cu2+ ions, respectively, both of which have been confirmed to be very comparable or better than the reported LMOFs sensors. The possible photoluminescence quenching mechanisms were studied in detail, revealing that the competitive absorption of excitation source and resonance energy transfer (RET) resulted from the host (imidazole of the framework, Lewis basic sites)-guest (metal ions of Cu2+ and Fe3+, Lewis acid sites) interaction should be responsible for high efficiency fluorescence quenching. The binding energies of metal ions adsorption on the ZIF-8 obtained by DFT simulation were further performed to explain the higher quenching effect of Fe3+ than Cu2+.

Green synthesis of graphene gold nanocomposites for optical sensing of ferritin biomarker

The combination of graphene oxide with gold nanoparticles offers enhanced optical properties with strong surface plasmon resonance, good biocompatibility, improved stability and ultrasensitive detection. This study aims to synthesize ecofriendly graphene oxide gold nanocomposites for sensing of ferritin biomarker, which is vital for diagnosing anemia as well as severe COVID conditions. Herein, an affordable and label free technique was proposed for detection of ferritin. The graphene oxide gold nanocomposites are synthesized by a simple one pot chemical reaction utilizing natural reducing agents. The alterations in the optical spectral characteristics of graphene gold nanocomposites upon interaction with the Fe3+ ions as well as ferritin protein are investigated. The proposed label free technique achieved a limit of detection of 1 μM for Fe3+ ions and 1 μg/ml for Ferritin protein.

Facile and Green synthesis of fluorescent N-doped carbon dots from betel leaves for sensitive detection of Picric acid and Iron ion

In this present work, a facile, green, cost effective route has been applied for the synthesis of water soluble carbon dots from betel leaves by hydrothermal route. As obtained nitrogen doped carbon dots (N-CDs) show remarkable advantages such as water solubility, biocompatibility and excellent stability. It is analyzed by vital characterization techniques such as HR-TEM, AFM, PSA, XRD, XPS, FTIR, UV-–vis and fluorescence spectroscopy with lifetime analysis. It exhibits blue emission under UV lamp (wavelength 365 nm), excitation dependent emission behavior and independent of pH. The obtained N-CDs show excellent response to picric acid (PA) and Fe3+ ions which leads to fluorescence quenching. This phenomenon was applied to design a single probe fluorescence based system for dual detection with high selectivity and sensitivity. A good linear response was obtained between concentration of analyte and fluorescence intensity with limit of detection (LOD) 0.11μM in the range of 0.3−3.3μM for PA and 0.135μM in the range of 0.3−3.3μM for Fe3+. Finally, the obtained fluorescent probe could be a promising tool for sensitive detection of PA and Fe3+ in aqueous solution.

A water-stable 3D Zn(II) luminescent coordination polymer for highly sensitive and selective sensing of acetylacetone and Fe3+ ion

A water-stable luminescent coordination polymer [Zn(L)0.5(2,6-NDC)]n (1) (L = 1,6-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)hexane, 2,6-H2NDC = 2,6-naphthalenedicarboxylic acid) was hydrothermally synthesized and characterized. 1 possesses a 3D framework with 6-connected pcu topology. The structure of 1 could remain stable during the pH of 3.0–11.0. 1 can be utilized as a quick-responsive luminescent probe for sensing of acetylacetone (acac) and Fe3+ ions. The limit of detection is 5.29 μM for acac, and 0.82 μM for Fe3+, respectively.

Flexible and reusable carbon dot decorated natural microcline membrane: a futuristic probe for multiple heavy metal induced carcinogen detection.

A flexible nano-engineered natural mineral (carbon dot doped natural microcline) based membrane (MCPV) has been developed, which can efficiently detect the presence of hexavalent chromium (Cr6+) and trivalent iron (Fe3+) ions in water by altering its fluorescence emission. Detailed characterization of the membrane was carried out using XRD, FT-IR spectroscopy, FESEM, TEM, and UV-Vis spectroscopy. Mechanical and temperature stabilities were also investigated. This new-generation sensor membrane is designed in such a way that it does not dissolve in water, keeping the water quality unaffected. The fluorescence studies were conducted at 414nm and "turn-off" response was observed specifically for Fe3+ at 489nm. A prominent red shift (530nm) of the fluorescence maxima takes place when it comes to Cr6+. Figures of merit, such as LOD (8.7μM for Cr6+ and 18.4μM for Fe3+) and LOQ (29.1μM for Cr6+ and 61.6μM for Fe3+), were evaluated from the linear range (0-60μM for Cr6+ and 0-30μM for Fe3+) of the calibration curve (Stern-Volmer plots) showing high sensitivity of this sensing probe toward Cr6+ and Fe3+. Recovery and RSD calculations were done in various real-life water samples on intraday-interday basis to determine the accuracy of the sensor. This work validates the fact that the synthesized sensor membrane is capable of detecting these heavy metals in glutathione environment as well, which could be beneficial for early-stage carcinogen detection in living cells.

Terbium-functionalized silica nanoparticles for metal ion sensing by fluorescence quenching

We describe preparation of a new luminescent material based on silica nanoparticles functionalized with terbium (Tb3+) complex of a polyamino polycarboxylic chelator, which displayed fluorescence when dispersed in aqueous and organic solvents. The functionalized material, TbL@SiO2, was firstly characterized by FTIR, UV–Vis and photoluminescent (PL) measurements. Further, it was used for various metal ions sensing as monitored by fluorescence quenching, indicating the highest decrease for iron(III), copper(II) and cobalt(II) metal ions. The calculated Stern-Volmer constants (KSV) equalled 2.21 × 105 M−1 for Fe3+, 6.81 × 105 M−1 for Cu2+ and 9.26 × 105 M−1 for Co2+, while the resulted lower detection limits reached 0.17 μM, 0.10 μM and 0.13 μM for Fe3+, Cu2+ and Co2+ respectively. In addition, the quenching mechanism was investigated through lifetime measurements which revealed a dynamic nature upon increase of the transition metal ion concentration. This was evidenced by changes in the emission lifetime (from τ0 = 1600 μs to τq = 1102 μs, thus a decrease of 31% in lifetime in presence of 8.6 μM Cu2+), most probably due to the collision interactions that affected the energy transfer of the ligand towards terbium ions.

A water-stable lanthanide-MOF as a highly sensitive and selective luminescence sensor for detection of Fe3+ and benzaldehyde

This paper studies the application of lanthanide metal-organic frameworks (Ln-MOFs) in fluorescence detection. The europium-based metal-organic frameworks (Eu-MOFs) are synthesized by a facile solvothermal method, and then the as-prepared MOF were further characterized by PXRD, FT-IR, TG, EDS, SEM, UV–vis spectra and fluorescence spectroscopy. The results demonstrate that Eu-MOF exhibits an intense red fluorescence, which can be readily observed by naked eye in solid state, good structural stability and fluorescence stability in aqueous solution or other organic solvents, especially high selectivity and sensitivity to Fe3+ and benzaldehyde and the visible color change by the naked eye under UV-light. This luminescent MOF can be used to detect Fe3+ and benzaldehyde in an aqueous environment with low detection limits of 0.027 μM for Fe3+ and 0.011 μM for benzaldehyde.

Multi-anthracene containing fluorescent probe for spectrofluorimetric iron determination in environmental water samples

An anthracene-based fluorescence (FL) system was synthesized via a general synthetic procedure. Fourier transform infrared spectroscopy (FTIR), MALDI-MS, and nuclear magnetic resonance spectroscopy (13C and 1H NMR) were carried out to characterize the multi-anthracene containing probe. The photophysical properties of the probe were illustrated via 3D-FL analysis and excitation-emission matrix (EEM) measurements. Density-functional theory (DFT) was applied to optimize the structure of the prepared probe and investigate its molecular interactions with Fe3+. The FL proficiency of the probe was appraised by spectroscopic measurements like Ultraviolet–Visible (UV–Vis) and FL spectroscopies. The simple and highly sensitive probe was able to diagnose ferric ions’ low concentrations and detection limit reached upto 0.223 µM with linear working range between 0.22 and 92.00 µM for Fe3+ ions. The efficacy of this fluorescent probe was confirmed by testing for iron determination in environmental samples. Various fluorophores or ionophores could be applied for achieving novel probes by the proposed procedures and for diagnosing diverse metal ions.

A multi-functional picolinohydrazide-based chemosensor for colorimetric detection of iron and dual responsive detection of hypochlorite.

A novel effective chemosensor HPHN, (E)-6-hydroxy-N'-((2-hydroxynaphthalen-1-yl)methylene) picolinohydrazide, was synthesized. HPHN sensed Fe3+/2+ with the changes of color from yellow to orange without obvious inhibition from other cations. In addition, HPHN could detect ClO- by both the color change from yellow to colorless and the fluorescence quenching. The binding modes of HPHN with Fe3+/2+ and ClO- were determined to be 1:1 with Job plot and ESI-mass analysis. HPHN displayed low detection limits of 0.29μM for Fe3+ and 0.77μM for Fe2+. For ClO-, the detection limit was 6.20μM by colorimetric method and 3.99μM by fluorescent one, respectively. Moreover, HPHN can be employed to quantify Fe3+ and ClO- in environmental samples and apply to cell imaging for ClO-.

A dual-emission Acf@bioMOF-1 platform as fluorescence sensor for highly efficient detection of inorganic ions

An anionic bio-MOF-1 with 1D square channels is applied as container for the adsorption of organic dyes owing to the porous structure and charge properties. Through ion exchange, cationic acriflavine (Acf) dye with the minimum size is selected as a fluorescent dye molecule to introduce into the pores of anionic bio-MOF-1 to obtain a self-calibrating dual-emitting fluorescent composite of Acf@bio-MOF-1, which exhibits two characteristic emission peaks at 385 and 582 ​nm. The composite acts as fluorescence sensing probe for the selective and sensitive detection of Fe3+, Al3+ and Cr2O72− among metal cations and anions and has a “turn-off” response to Fe3+ and Cr2O72− as well as a “turn-on” response to Al3+ at the same time. Particularly, Acf@bio-MOF-1 shows higher fluorescence quenching effects of 95% for Cr2O72− and 90% for Fe3+ and low detection limits of 0.25 ​μM for Cr2O72− and 1.33 ​μM for Fe3+, respectively. Such a special encapsulation strategy to form a dual-emission platform can be adopted to the detection of inorganic ions sensitively.

Detection of Ferric Ions and Catecholamine Neurotransmitters via Highly Fluorescent Heteroatom Co-Doped Carbon Dots.

Carbon dots (CDs) demonstrate very poor fluorescence quantum yield (QY). In this study, with the help of a hydrothermal method, we combined CDs with nitrogen and phosphorus elements belonging to the VA group (in the periodic table) to form heteroatom co-doped CDs, i.e., nitrogen and phosphorus co-doped carbon dots (NPCDs). These displayed a significant improvement in the QY (up to 84%), which was as much as four times than that of CDs synthesized by the same method. The as-prepared NPCDs could be used as an “off-on” fluorescence detector for the rapid and effective sensing of ferric ions (Fe3+) and catecholamine neurotransmitters (CNs) such as dopamine (DA), adrenaline (AD), and noradrenaline (NAD). The fluorescence of NPCDs was “turned off” and the emission wavelength was slightly red-shifted upon increasing the Fe3+ concentration. However, when CNs were incorporated, the fluorescence of NPCDs was recovered in a short response time; this indicated that CN concentration could be monitored, relying on enhancing the fluorescence signal of NPCDs. As a result, NPCDs are considered as a potential fluorescent bi-sensor for Fe3+ and CN detection. Particularly, in this research, we selected DA as the representative neurotransmitter of the CN group along with Fe3+ to study the sensing system based on NPCDs. The results exhibited good linear ranges with a limit of detection (LOD) of 0.2 and 0.1 µM for Fe3+ and DA, respectively.

Facile synthesis of amino‐functionalized polyphosphazene microspheres and their application for highly sensitive fluorescence detection of Fe3+

ABSTRACTAmino‐functionalized highly crosslinked organic–inorganic hybrid polyphosphazene microspheres were prepared via a one‐pot polycondensation method and served as a fluorescent sensor for the detection of Fe3+ in solution. With the introduction of p‐phenylenediamine unites, the polyphosphazene microspheres could be endowed with fluorescent property and abundant active amino groups on the surface. The microspheres were further used as the fluorescent sensor for the detection of Fe3+. Fluorescence study showed high sensing sensitivity and selectivity of the microspheres, and the limit of detection was determined as 0.076 μM for Fe3+. Active amino groups on the surface could efficiently improve the detection sensitivity of Fe3+. Moreover, highly crosslinked organic–inorganic hybrid structure was beneficial to the photostability and thermostability, enabled the microspheres to be possible for constructing practicable sensors. This work is expected to inspire the design of advanced polyphosphazene‐based fluorescent sensors for applications in analytical detection. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48937.

Hydroxylated graphene quantum dots as fluorescent probes for sensitive detection of metal ions

Highly sensitive methods are important for monitoring the concentration of metal ions in industrial wastewater. Here, we developed a new probe for the determination of metal ions by fluorescence quenching. The probe consists of hydroxylated graphene quantum dots (H-GQDs), prepared from GQDs by electrochemical method followed by surface hydroxylation. It is a non-reactive indicator with high sensitivity and detection limits of 0.01 μM for Cu2+, 0.005 μM for Al3+, 0.04 μM for Fe3+, and 0.02 μM for Cr3+. In addition, the low biotoxicity and excellent solubility of H-GQDs make them promising for application in wastewater metal ion detection.

Development of sulfur doped carbon quantum dots for highly selective and sensitive fluorescent detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples.

Sulfur-doped carbon quantum dots (S-CQDs) with stable blue fluorescence were synthesized through a facile one-step hydrothermal method by using ascorbic acid and thioglycolic acid as carbon and sulfur sources. The prepared S-CQDs exhibited a sensitive and selective response to Fe3+ ions in comparison with Fe2+ and other metal ions, In the presence of adequate H2O2, Fe2+ was completely transformed to Fe3+ that is the determinable form of iron ions, and the difference in the change of the fluorescence intensity of S-CQDs before and after adding H2O2 was used for detection of Fe2+ and Fe3+ ions, respectively. Under the optimum experimental conditions, the fluorescence intensity of S-CQDs gradually decreased with increasing of Fe3+ concentration ranging from 0 to 200 μM. Good linearity was achieved over the range of 0-200 μM. The detection limit of the developed method was 0.050 μM for Fe3+. The recoveries of Fe2+ and Fe3+ spiked in real samples ranged from 98.2% to 112.4%. Finally, the proposed S-CQDs integrated with Fenton system was applied to the detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples, which presents potential applications in the speciation and determination of Fe2+ and Fe3+ ions in complex samples.

A lysosome-targetable fluorescent probe for imaging trivalent cations Fe3+, Al3+ and Cr3+ in living cells.

An effective morpholine-type naphthalimide chemsensor, N-p-chlorophenyl-4-(2-aminoethyl)morpholine-1,8-naphthalimide (CMN) has been developed as a lysosome-targeted fluorometric sensor for trivalent metal ions (Fe3+, Al3+ and Cr3+). Upon the addition of Fe3+, Al3+ or Cr3+ ions, the probe CMN showed an evident naked-eye color changes which pale yellow solution of CMN turned deepened and it displayed turn-on fluorescence response in methanol. CMN showed a significant selective and sensitive toward Fe3+, Al3+ or Cr3+ ions, while there was no obvious behavior to other monovalent or divalent metal ions from the UV-vis and fluorescence spectrum. Based on the Job's plot analyses the 1:1 coordination mode of CMN with Fe3+, Al3+ or Cr3+ was proposed. The limit of detection (LOD) observed were 0.65, 0.69 and 0.68 μM for Fe3+, Al3+ and Cr3+ ions, respectively. The N-atom of morpholine directly involved in complex formation, CMN emitted fluorescence through inhibition of photoinduced electron transfer (PET). This probe exhibited excellent imaging ability for Fe3+, Al3+and Cr3+ ions in living cells with low cytotoxicity. Significantly, the cellular confocal microscopic research indicated that the lysosome-targeted group of morpholine moiety was introduced which realized the capability of imaging lysosomal trivalent metal ions in living cells for the first time.

Pyrene Based Fluorescent Turn-on Chemosensor for Sequential Detection of Fe3+ and Fe2+ Ions and its Application in Live Cell Imaging.

A simple pyrene-based "turn-on" chemosensor bearing isonizide namely 3-(pyren-1-yl methylene) pentane-2,4-diyldene di(isonicotinohydrazide) (PMPD) was designed and synthesized for detecting Fe3+and Fe2+ ions in HEPES buffer solution at pH7.4 (DMSO: H2O (1:9v/v)) medium. The probe shows conducive selectivity for Fe2+ and Fe3+ ions over the other competitive metal cations. The detection limit was found to be 1.67μM for Fe3+ and 2.02μM for Fe2+. The recognition mechanism of PMPD towards Fe3+ and Fe2+ has been examined in detail by absorption, emission, and ESI-MS studies. Moreover, "turn-on" fluorescence behavior of the probe was used to track iron ions in living cells.

Oxadiazole-based ‘on-off’ fluorescence chemosensor for rapid recognition and detection of Fe2+ and Fe3+ in aqueous solution and in living cells

An oxadiazole-based chemosensor (sensor 1) for Fe3+/Fe2+ was successfully designed and synthesized. Sensor 1 displayed fluorescence quenching response towards both Fe3+ and Fe2+ in THF:H2O (4:1, v/v) solvent with high selectivity and sensitivity over all other competitive metal ions. Job's plot, mass spectra, DFT calculation and fluorescence titration disclosed that fluorescence quenching was caused by forming 1:1 complex between sensor 1 and iron ions. Sensor 1 presented high sensitive fluorescence response at the pH value of human body and its fluorescence intensity showed linear relationship with the concentration of iron ion. Sensor 1 also presented fast fluorescence response towards iron ions and the lower detection limit, 7.78 μM for Fe2+ ion and 6.95 μM for Fe3+ ion, respectively. Sensor 1 can be used as test strips to detect iron ions in water samples. Fluorescence cell imaging also demonstrated sensor 1 can recognize iron ions in living cells.

A rhodamine-based novel turn on trivalent ions sensor

In this study, a new rhodamine derivative (Rhodamine dipyridyl (the probe RDP)) was synthesized for trivalent ions selectivity based on colorimetric and fluorometric detection. The effects of different metal ions such as Li+, Na+, K+, Ag+, Mg2+, Ca2+, Ba2+, Cd2+, Zn2+, Cu2+, Hg2+, Pb2+, Fe2+, Mn2+, Co2+, Fe3+, Cr3+, and Al3+ on the photo-physical properties of the probe RDP were investigated in water/ethanol (1:1, v/v). According to the data obtained, a new peak at 560 nm in the absorption spectrum of the probe RDP and an increase in fluorescence intensity of its were observed in the presence of Fe3+, Cr3+, and Al3+ (M3+) ions. The binding constants were calculated using the Benesi-Hildebrand equation and found to be 1.42 × 103 M−1 for Fe3+, 3.88 × 103 M−1 for Al3+ and 9.16 × 103 M−1 for Cr3+. The limit of detection (LOD) values were found to be 1.17 μM for Al3+, 2.50 μM for Fe3+ and 3.16 μM for Cr3+. The interaction ratio between the probe RDP and M3+ ions was determined as 1:2. Also, the response times of the probe RDP were less than 1 min for trivalent ions.