Determination of iron(III) based on the fluorescence quenching of rhodamine B derivative

Determination of baloxavir marboxil in pharmaceutical preparations and spiked human plasma using its quenching action on acetoxymercuric fluorescein reagent: Assessment of greenness and whiteness

A straightforward, reliable, and cost-effective spectrofluorimetric approach has been established for the analysis of baloxavir marboxil (BXM) in raw material, tablets, as well as spiked human plasma. The approach relies on BXM's quenching impact on acetoxymercuric fluorescein (AMF) fluorescence intensity. To improve the reaction, factors such as AMF's concentration, solution's pH, diluting solvents, and reaction time were examined and optimized. Linearity, range, accuracy, precision, LOD, and LOQ were all verified in compliance with ICH criteria. The concentration range was shown to be linear between 0.2 and 2 μg/mL. The technique was effectively utilized for BXM analysis in both its tablet as well as spiked human plasma, with mean % recoveries of 101 ± 0.36 and 98.77 ± 0.65, respectively. Two assessment models (AGREE and RGB-12) were used to compare the proposed process's greenness and sustainability to four previously published chromatographic techniques. Higher green and sustainability qualities were declared by the suggested approach than by earlier ones.

Pulsed Electric Field (PEF) Enhances Iron Uptake by the Yeast Saccharomyces cerevisiae

The aim of the study was to investigate the influence of a pulsed electric field (PEF) on the level of iron ion accumulation in Saccharomyces cerevisiae cells and to select PEF conditions optimal for the highest uptake of this element. Iron ions were accumulated most efficiently when their source was iron (III) nitrate. When the following conditions of PEF treatment were used: voltage 1500 V, pulse width 10 μs, treatment time 20 min, and a number of pulses 1200, accumulation of iron ions in the cells from a 20 h-culture reached a maximum value of 48.01 mg/g dry mass. Application of the optimal PEF conditions thus increased iron accumulation in cells by 157% as compared to the sample enriched with iron without PEF. The second derivative of the FTIR spectra of iron-loaded and -unloaded yeast cells allowed us to determine the functional groups which may be involved in metal ion binding. The exposure of cells to PEF treatment only slightly influenced the biomass and cell viability. However, iron-enriched yeast (both with or without PEF) showed lower fermentative activity than a control sample. Thus obtained yeast biomass containing a high amount of incorporated iron may serve as an alternative to pharmacological supplementation in the state of iron deficiency.

Fluorescence determination of trace level of cadmium with pyrene modified nanocrystalline cellulose in food and soil samples

Cadmium is one of the most toxic metal that accumulates in the human body via food chain, industrial/agricultural activites. It also has negative effects in organs such as the brain, liver and central nervous system. Therefore, International Agency for Research on Cancer is classified cadmium as "carcinogenic to humans" (group 1). In this work, novel pyrene modified nanocrystalline cellulose (NP-1) was designed as a fluorescence sensor for selective determination of Cd²⁺ in food and soil samples. FTIR, UV-Vis, SEM, TEM and TGA were used for structural, morphological characterizations and thermal properties of NP-1. The experimental conditions such as selectivity, pH, sensor concentration, photostability, time and interaction mechanism were examined and optimized. The LOD was determined as 0.09 μM (10.70 μg/L) which was lower than WHO's permissible limit of cadmium in plant with 0.10-60.00 μM linear working range. Validation of the present method was performed by spike/recovery test and ICP-MS, then fluorescence determination of Cd²⁺ in food and soil samples was succesfully applied. The results indicated that the proposed method based on "turn-on" fluorescence of NP-1 was a simple, sensitive and reliable for rapid determination of Cd²⁺ in real samples with high applicability and stability.

A novel colorimetric and fluorometric probe for biothiols based on MnO2 NFs-Rhodamine B system

Herein, a novel bimodal ratiometric probe for sensitive and selective detection of biothiols (including glutathione (GSH), cysteine (Cys) and homocysteine (Hcys)) was constructed, which was based on the redox reaction between manganese dioxide nanoflakes (MnO₂ NFs) and rhodamine (RhB) and biothiols. When MnO₂ NFs was added into RhB solution, RhB was oxidized to a series of derivatives, accompanying with the colorimetric color changing from purple to light pink and fluorescence changing from red to green. In the presence of GSH, Cys or Hcys, they could reduce MnO₂ NFs to Mn²⁺, thereby preventing the following oxidization of RhB and the corresponding color and fluorescence changes. The absorption intensity ratio and fluorescence intensity ratio showed good linear relationships with the concentrations of biothiols. The colorimetric detection limits for GSH, Cys and Hcys were 0.057 μM, 0.140 μM and 0.087 μM, respectively. And the fluorescence detection limits were 0.177 μM, 0.282 μM and 0.161 μM. More importantly, this probe was successfully applied to monitor the concentration of GSH/Cys/Hcys in human serum samples, with satisfactory recovery. Thus, this MnO₂ NFs-RhB platform can potentially be a candidate for the detection of biothiols.

Synthesis, optical, and structural properties of bisphenol-bridged aromatic cyclic phosphazenes

Phenoxy- and naphthoxy-substituted bisphenol-bridged cyclic phosphazenes were synthesized in 2 steps and their thermal, photophysical, and electrochemical properties were investigated. The structures of the cyclic phosphazene compounds were determined by ESI-MS mass spectrometry and 1 H, 13 C, and 31 P NMR spectroscopies. The photophysical studies of phenoxy- and naphthoxy-substituted bridged cyclophosphazenes were investigated by means of absorption and fluorescence spectroscopies in different solvents. Thermal and electrochemical properties of the target compounds were also studied. Furthermore, the excimer emissions through intramolecular interactions in solution and in solid state were investigated by fluorescence spectroscopy and the theoretical calculations were performed in detail using DFT.

Synthesis of a novel hexaazatriphenylene derivative for the selective detection of copper ions in aqueous solution

A hexaazatriphenylene (HAT) derivative, naphtho[2,3-h]naphtho[2',3':7,8]quinoxalino[2,3-a]naphtho[2',3':7,8]quinoxalino[2,3-c]phenazine-5,10,15,20,25,30-hexaone (NQH) was synthesized, characterized, and found to have novel properties in being selective toward the detection of copper (Cu2+) ions. The capability of NQH to be employed as a colorimetric, chemo-fluorescence and electrochemical sensor for the detection of Cu2+ was demonstrated by performing UV-Vis absorbance, fluorescence intensity, and cyclic voltammetry (CV) measurements. The interaction between NQH and Cu2+ was initially observed with an obvious color change from yellow to brown upon the addition of Cu2+ ions to NQH. The interaction was also confirmed by UV-Vis absorbance, fluorescence intensity, and mass spectroscopy (MS/MS) measurements. UV absorbance, fluorescence and CV of NQH toward Cu2+ showed good linearity with a detection limit of 3.32 μM, 2.20 μM and 0.78 μM, respectively, which are lower than the toxicity levels of copper in drinking water (20-30 μM) set by the U.S. Environmental Protection Agency (EPA) and World Health Organization (WHO). A 1 : 2 stoichiometry complexation between NQH and Cu2+ was confirmed by Job's plot and MS/MS. In addition, the selectivity and sensitivity of the NQH compound towards Cu2+ ions were further confirmed by performing CV on a screen printed flexible and planar electrochemical sensor.

Employment of Iron-Binding Protein from Haemophilus influenzae in Functional Nanopipettes for Iron Monitoring

Because of the serious neurologic consequences of iron deficiency and iron excess in the brain, interest in the iron status of the central nervous system has increased significantly in the past decade. While iron plays an important role in many physiological processes, its accumulation may lead to diseases such as Huntington's, Parkinson's, and Alzheimer's. Therefore, it is important to develop methodologies that can monitor the presence of iron in a selective and sensitive manner. In this paper, we first showed the synthesis and characterization of the iron-binding protein (FBP) from Haemophilus influenzae, specific for ferrous ions. Subsequently, we employed this protein in our nanopipette platform and utilized it in functionalized nanoprobes to monitor the presence of ferrous ions. A suite of characterization techniques: absorbance spectroscopy, dynamic light scattering, and small-angle X-ray scattering were used for FBP. The functionalized Fe-nanoprobe calibrated in ferrous chloride enabled detection from 0.05 to 10 μM, and the specificity of the modified iron probe was evaluated by using various metal ion solutions.

Logic gate behavior and intracellular application of a fluorescent molecular switch for the detection of Fe3+ and cascade sensing of F− in pure aqueous media

The nature and coordination sites of a Schiff base 3,3′-(1E,1′E)-(1,3-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol (APHN), are tuned by its selective reduction to design a highly efficient fluorescent probe RAPHN.

Graphene oxide/nanometal composite membranes for nanofiltration: synthesis, mass transport mechanism, and applications

We reviewed the recent developments in graphene-based composite membranes and discussed their challenges in this paper.

Speciation determination of iron and its spatial and seasonal distribution in coastal river

In this study, the speciation of iron (Fe), including total Fe (TFe) and acidified dissolved Fe (ADFe), was assessed by fast cathodic absorption stripping voltammetry, using a gold electrode and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) as a novel complexing agent for Fe. The validity and accuracy of this method were compared with the standard spectrophotometry and tested by the standard samples. Under optimized conditions, the Fe response was linear within the range of 0.01 to 1 μM with a detection limit of 1.2 nM. To further validate this method, the variation in concentrations of TFe and ADFe were investigated at twelve sampling stations in a local coastal river, in both the dry and wet season. Additionally, to further understand the interaction between Fe and environmental factors, the relationships between the concentration of Fe species and dissolved oxygen (DO) and salinity were also discussed.

Signalling probes appended with two rhodamine derivatives: inter-component preferences, Fe(iii)-ion selective fluorescence responses and bio-imaging in plant species

Molecular probes (1 and 2) incorporating two different xanthene dyes exhibited Fe(iii) selective dual mode signaling responses.

A highly selective fluorescent chemosensor for Fe3+ based on a new diarylethene with a rhodamine 6G unit

A new multi-functional diarylethene-rhodamine 6G derivative was synthesized; its colorimetric and fluorometric sensing ability for Fe³⁺/EDTA, TFA/TEA and switching behaviors induced by light were investigated.

Tuning photoluminescence and surface properties of carbon nanodots for chemical sensing

Obtaining tunable photoluminescence (PL) with improved emission properties is crucial for successfully implementing fluorescent carbon nanodots (fCDs) in all practical applications such as multicolour imaging and multiplexed detection by a single excitation wavelength. In this study, we report a facile hydrothermal approach to adjust the PL peaks of fCDs from blue, green to orange by controlling the surface passivation reaction during the synthesis. This is achieved by tuning the passivating reagents in a step-by-step manner. The as-prepared fCDs with narrow size distribution show improved PL properties with different emission wavelengths. Detailed characterization of fCDs using elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy suggested that the surface chemical composition results in this tunable PL emission. Surface passivation significantly alters the surface status, resulting in fCDs with either stronger surface oxidation or N element doping that ultimately determine their PL properties. Further experiments suggested that the as-prepared orange luminescent fCDs (O-fCDs) were sensitive and specific nanosensing platforms towards Fe(3+) determination in a complex biological environment, emphasizing their potential practical applications in clinical and biological fields.

5-(N-Ethylcarbazol-3-yl)thiophene-2-carbaldehyde (ECTC): a novel fluorescent sensor for ferric ion

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A new Rhodamine B-based 'on-off' chemical sensor with high selectivity and sensitivity toward Fe(3+) and its imaging in living cells

A new fluorescent chemosensor based on a Rhodamine B and pyrrole conjugate (RBPY) has been designed and synthesized. UV-vis absorption and fluorescence spectroscopic studies show that RBPY exhibits a high selectivity and sensitivity toward Fe(3+) among many other metal cations in a MeOH/H2O solution (3:2, v/v, pH 7.10, HEPES buffer, 0.1mM) by forming a 1:1 complex with Fe(3+). Furthermore, results reveal that the formation of the RBPY-Fe(3+) complex is fully reversible in the presence of sulfide anions and could also be used as an efficient sensor for S(2-). Importantly, fluorescence microscopy experiments further demonstrated that RBPY can be utilized as a fluorescent probe for the detection of Fe(3+) in human liver (L-02) cells.

A highly selective fluorescent probe for Cu2+ based on rhodamine B derivative

A new fluorescent probe 1 for Cu(2+) based on a rhodamine B derivative was designed and synthesized. Probe 1 displays high sensitivity toward Cu(2+) and about a 37-fold increase in fluorescence emission intensity is observed upon the addition of 10 equiv. Cu(2+) in 50% water/ethanol buffered at pH 7.10. Besides, upon binding Cu(2+) a remarkable color change from colorless to pink was easily observed by the naked eyes. The reversible dual chromo- and fluorogenic response toward Cu(2+) is likely due to the chelation-induced ring-opening of rhodamine spirolactam. The linear response range covers a concentration range of Cu(2+) from 8.0×10(-7) to 1.0×10(-4) mol/L and the detection limit is 3.0×10(-7) mol/L. Except Co(2+), the probe exhibits high selectivity for Cu(2+) over a large number of cations such as alkaline, alkaline earth and transitional metal ions. The accuracy and precision of the method were evaluated by the analysis of the standard reference material, copper in water (1.0 mol/L HNO3). The proposed probe has been used for direct measurement of Cu(2+) content in river water samples and imaging of Cu(2+) in living cells with satisfying results, which further demonstrates its value of practical applications in environmental and biological systems.

Spectral properties of 4-(4-hydroxy-1-naphthylazo)benzenesulfonic acid and its application for colorimetric determination of trace Fe3+

A multifunctional dye, 4-(4-hydroxy-1-naphthylazo)benzenesulfonic acid was identified and synthesized and used to determine trace Fe³⁺ in three real environmental water samples. The mechanism of action between the dye and Fe³⁺ ion is discussed in detail.