Iron metabolism

A sensitive "turn-on" Schiff-base fluorescent probe for the selective detection of Fe3+ and bio-imaging

A novel Schiff-base fluorescent probe, 4-(N-(2- hydroxyl-1-naphthalymethylimino)-ethylamino) -7-nitro-1,2,3-benzoxadiazole (HENB) was synthesized and utilized for spectral sensing of Fe3+ ions at neutral pH. The binding of Fe3+ to HENB in C2H5OH-HEPES buffer (1:1 v/ v, 25 mM, pH 7.2) resulted in a pronounced emission enhancement at 530 nm, which is possibly due to the inhibition of photo-induced electron transfer (PET) process as well as the chelation enhanced fluorescence (CHEF) effect. HENB shows good selectivity and sensitivity toward Fe3+ with the detection limit as low as 4.51 nM. Test strips made of HENB was used for rapid "naked-eye" detection of Fe3+ ions in aqueous medium. Moreover, HENB was successfully applied in fluorescence imaging of exogenous and endogenous Fe3+ in live Hela cells as well as zebrafish. Importantly, HENB is capable of effectively monitoring the variations of Fe3+ in living cells during ferroptosis process.

A multifunctional quinoxaline-based chemosensor for colorimetric detection of Fe3+ and highly selective fluorescence turn-off response of Cu+2 and their practical application

A new dual responsive colorimetric and fluorescent turn-off sensor for Fe3+ and Cu2+ was designed and synthesized based on quinoxaline derivative by a simple procedure reaction. 2,3-bis(6-bromopyridin-2-yl)-6-methoxyquinoxaline (BMQ) was fabricated and characterized using ATR-IR, 13C and 1H NMR, and Mass spectroscopy. The interaction of BMQ with Fe3+ caused a significant color change from colorless to yellow. The sensing complex BMQ-Fe3+ with high selectivity was described to be 1:1 by the molar ratio plot. In this experiment, iron was detected by naked-eye using a recently synthesized ligand (BMQ). This color change was unexpectedly observed in iron-overloaded plasma, which had previously been admitted by AAS (Atomic Absorption Spectroscopy). Normal plasma, however, did not exhibit this color change. Interestingly, Cu2+ ions cause a quench at the local emission around 565 nm. On the other hand, receptor-binding selectivity for Cu2+ over a wide linear concentration range was observed through changes in the emission spectra. BMQ-Cu2+ was characterized to be 1:1 by the Job's plot. The emission intensity of BMQ-Cu2+ complex was balanced within only 1 min. various mineral water samples were analyzed for detecting Cu2+. The results show the great potential of the developed probe BMQ for the sensing of Cu2+ ions in mineral and drinking water samples.

Salicylic acid doped silica nanoparticles as a fluorescent nanosensor for the detection of Fe3+ in aqueous solution

A novel organic-inorganic hybrid nanosensor (SASP) was prepared by a one-step sol-gel method and characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, N2 adsorption-desorption, fluorescence spectroscopy, etc. The nanosensor showed almost 3-fold fluorescence emission quenching upon excitation with a 293 nm wavelength in the presence of 20 μM Fe3+ ions. The presence of 18 other metal ions had no observable effect on the sensitivity and selectivity of the nanosensor. A fluorescence analysis method based on the SASP for the selective detection of Fe3+ was established under optimal conditions. The results showed that there was a linear relationship between the log luminescence value and the concentration of Fe3+ over the range of 2.0 × 10-7-9.0 × 10-5 mol L-1 with a detection limit (3σ) of 2.5 × 10-8 mol L-1. Furthermore, the proposed method was successfully applied for the determination of trace Fe3+ in fetal bovine serum without the interference of other molecules and ions. Good recovery (96.5-104.5%) and a relative standard deviation of less than 8.6% were obtained from serum samples spiked with four levels of Fe3+. Additionally, the nanosensor showed a good reversibility; the fluorescence could be switched "off" and "on" in two ways, by adjusting the pH of the solution and adding metal chelating agent EDTA.

The role of iron in the pathogenesis of endometriosis: a systematic review

STUDY QUESTION

What is the role of iron in the pathophysiology of endometriosis?

SUMMARY ANSWER

Iron excess is demonstrated wherever endometriotic tissues are found and is associated with oxidative stress, an inflammatory micro-environment, and cell damage; the iron-mediated oxidative stress is independently linked to subfertility, symptom severity, and malignant transformation.

WHAT IS KNOWN ALREADY

Iron is found in excess in endometriotic tissues, and multiple mechanisms have been studied and posited to explain this. It is clear that iron excess plays a vital role in promoting oxidative stress and cell damage. The evidence base is large, but no comprehensive reviews exist to summarize our understanding and highlight the overarching themes to further our understanding and suggest future directions of study for the field.

STUDY DESIGN SIZE DURATION

This systematic review with a thematic analysis retrieved studies from the PubMed, Embase, Web of Science, and Cochrane Library databases and searches were conducted from inception through to August 2022. Human and animal studies published in the English language were included and identified using a combination of exploded MeSH terms ('Iron' and 'Endometriosis') and free-text search terms ('Iron', 'Ferric', 'Ferrous', 'Endometriosis', 'Endometrioma').

PARTICIPANTS/MATERIALS SETTING METHODS

This review was reported in accordance with the PRISMA guidelines. All studies reporting original data concerning the role of iron or iron complexes in the pathophysiology of endometriosis were included. Studies that did not report original data or provided a review of the field were excluded. Bias analysis was completed for each included study by using the Newcastle-Ottawa scoring system.

MAIN RESULTS AND THE ROLE OF CHANCE

There were 776 records identified and these were screened down to 53 studies which met the eligibility criteria, including 6 animal and 47 human studies, with 3556 individual participants. Iron excess is demonstrated in various tissues and fluids, including ovarian endometriomas, ovarian follicles, ectopic endometriotic lesions, and peritoneal fluid. Markers of oxidative stress are strongly associated with high iron levels, and aberrant expression of iron-transport proteins has been demonstrated. Abnormal resistance to ferroptosis is likely. Iron-mediated oxidative stress is responsible for a pro-inflammatory micro-environment and is linked to subfertility, symptom severity, and, possibly, malignant transformation.

LIMITATIONS REASONS FOR CAUTION

A minority of the included studies were of objectively low quality with a high risk of bias and may lead to misleading conclusions. Additionally, multiple studies failed to appropriately characterize the included patients by known confounding variables, such as menstrual cycle phase, which may introduce bias to the findings.

WIDER IMPLICATIONS OF THE FINDINGS

Current literature depicts a central role of aberrant iron mechanics and subsequent oxidative stress in endometriosis. It is likely that iron excess is at least partly responsible for the persistence and proliferation of ectopic endometriotic lesions. As such, iron mechanics represent an attractive target for novel therapeutics, including iron chelators or effectors of the iron-oxidative stress pathway. There are significant gaps in our current understanding, and this review highlights and recommends several topics for further research. These include the role of iron chelation, resistance to ferroptosis, the relationship between iron excess and localized hypoxia, systemic iron pathophysiology in endometriosis, and the role of oxidative stress in malignant transformation.

STUDY FUNDING/COMPETING INTERESTS

J.W. and S.G.P. are supported by clinical fellowships at Liverpool University Hospital NHS Foundation trust. No additional funding was requested or required for the completion of this work. C.J.H. is supported by a Wellbeing of Women project grant (RG2137). D.K.H. is supported by a Wellbeing of Women project grant (RG2137) and an MRC clinical research training fellowship (MR/V007238/1). The authors have no conflicts of interest to declare.

REGISTRATION NUMBER

A protocol was prospectively registered with the PROSPERO database in August 2021 (CRD42021272818).

A mitochondria-targeted fluorescent probe based on biocompatible RBH-U for the enhanced response of Fe3+ in living cells and quenching of Cu2+ in vitro

A rhodamine hydrazide conjugating uridine moiety (RBH-U) is firstly synthesized by screening different synthetic routes, and then developed as a fluorescence probe for selective detection of Fe³⁺ ions in an aqueous solution, accompanied by visual color change with naked eyes. Upon the addition of Fe³⁺ in a 1:1 stoichiometry, a 9-fold enhancement in the fluorescence intensity of the RBH-U was observed with an emission wavelength of 580 nm. In the presence of other metal ions, the "turn-on" fluorescent probe with pH-independent (value 5.0 to 8.0) is remarkably specific for Fe³⁺ with a detection limit as low as 0.34 μM. Further, the enhanced fluorescence intensity of RBH-U- Fe³⁺ can be quenched as a switch-off sensor to assist in the recognition of Cu²⁺ ions. Additionally, the colocalization assay demonstrated that RBH-U containing uridine residue can be used as a novel mitochondria-targeted fluorescent probe with rapid reaction time. Cytotoxicity and cell imaging of RBH-U probe in live NIH-3T3 cells suggest that it can be a potential candidate for clinical diagnosis and Fe³⁺ tracking toll for the biological system due to its biocompatibility and nontoxicity in NIH-3T3 cells even up to 100 μM.

Effects of dietary organic or inorganic iron concentrations on productive performance, egg quality, blood measurements, and tissue iron concentrations in aged laying hens

The objective of the current experiment was to investigate the effects of dietary organic or inorganic iron (Fe) concentrations on productive performance, egg quality, blood measurements, and tissue Fe concentrations in aged laying hens. A total of three hundred fifty 60-week-old Hy-Line Brown laying hens were allotted to one of five dietary treatments with seven replicates. Each replicate had 10 consecutive cages. Organic Fe (Fe-Gly) or inorganic Fe (FeSO₄ ) was added to the basal diet at the levels of 100 or 200 mg/kg Fe. Diets were fed on an ad libitum basis for 6 weeks. Results indicated that supplementation of organic or inorganic Fe in diets increased (p < 0.05) eggshell color and feather Fe concentrations compared with no supplementation of Fe in diets. An interaction was found (p < 0.05) between Fe sources and supplemental levels in diets for egg weight, eggshell strength, and Haugh unit. Hens fed diets supplemented with organic Fe had greater (p < 0.05) eggshell color and hematocrit than those fed diets supplemented with inorganic Fe. In conclusion, dietary supplementation of organic Fe increases the eggshell color of aged laying hens. High supplemental levels of organic Fe in diets improve egg weight in aged laying hens.

Ferroptosis in hepatocellular carcinoma: mechanisms and targeted therapy

Hepatocellular carcinoma is the most prevalent form of primary liver cancer with a multifactorial aetiology comprising genetic, environmental, and behavioural factors. Evading cell death is a defining hallmark of hepatocellular carcinoma, underpinning tumour growth, progression, and therapy resistance. Ferroptosis is a form of nonapoptotic cell death driven by an array of cellular events, including intracellular iron overload, free radical production, lipid peroxidation and activation of various cell death effectors, ultimately leading to rupture of the plasma membrane. Although induction of ferroptosis is an emerging strategy to suppress hepatocellular carcinoma, malignant cells manage to develop adaptive mechanisms, conferring resistance to ferroptosis and ferroptosis-inducing drugs. Herein, we aim at elucidating molecular mechanisms and signalling pathways involved in ferroptosis and offer our opinions on druggable targets and new therapeutic strategy in an attempt to restrain the growth and progression of hepatocellular carcinoma through induction of ferroptotic cell death.

Fast preparation of Eu(BTB) MOFs in dielectric barrier discharge liquid plasma for luminescent sensing of trace iron

Lanthanide metal-organic frameworks Eu(BTB) MOFs was synthesized in low-temperature plasma produced by dielectric barrier discharge (DBD). This DBD synthesis possesses the characteristics of rapid reaction (within 20 min), mild condition (low temperature and atmospheric pressure) and simple operation compared with many traditional synthesis methods. The prepared Eu(BTB) MOF material exhibits typical red light emitting of europium (Eu³⁺ ) at 617 nm, which can selectively and sensitively be quenched in the presence of trace iron(III) ion (Fe³⁺ ). A simple, fast and sensitive fluorescence sensing strategy of Fe³⁺ was thus constructed, with a limit of detection (LOD) of 0.5 μM. Compared with reported fluorescence probes, Eu(BTB) MOFs have also demonstrated the advantages of low cost, easy and fast preparation, great stability, and excellent optical properties, thus making them a promising fluorescence candidate for trace Fe³⁺ sensing for the potential application in biological systems in the future.

Novel schiff base as Fe3+ sensor as well as an antioxidant and its theoretical studies

A novel Schiff base derivative L (N1-(thiophene-2-ylmethylene)benzene-1,2-diamine) was synthesized via condensation reaction of 3-thiophene carboxaldehyde and 1,2-diamino benzene. The synthesized compound was authenticated using 1 H NMR, 13 C NMR, HRMS, and IR spectroscopy. The compound L was found to be a Fe3+ sensor with the complexation ratio of 1 : 3 as revealed by Job’s plot with maximum absorption at 318 nm. The photophysical properties were studied using absorption and emission spectra. DFT and TD-DFT studies were carried out in order to support the photophysical outcomes of compound L. An antioxidant behaviour of compound L was studied using TAC, FRAP, and DPPH assays and it was found to be showing better TAC activity than the used standard i.e. gallic acid.

Nanopore-Based Detection of Trace Concentrations of Multivalent Ions When Impurity Ions Are Present

The feasibility of detecting a trace concentration of multivalent ions based on the ionic current rectification (ICR) of a nanopore when impurity ions might present is assessed. Adopting a bullet-shaped nanopore surface modified with tannic acid as an example, the detection of trace concentrations of Cu²⁺ (target ion) when Fe³⁺ (impurity) is present with K⁺ as background ions under various conditions is simulated. In particular, the influence of the reaction order of the association of target ions and tannic acid on the nanopore performance is examined. We show that the lower the background concentration the better the detection performance. For the examined background concentrations of 1, 10, 100, and 1000 mM, the optimal detection ranges are [0.5, 1000 μM] and [1, 1000 nM] for Cu²⁺ and Fe³⁺, respectively. The detection limits, 0.5 μM for Cu²⁺ and 1 nM for Fe³⁺, are lower than those that can be obtained from conventional instruments, suggesting the potential of applying the present nanopore-based approach. In addition, we also consider the presence of multiple ions, which can occur, for example, in detecting Cu²⁺ (target ion) when Fe³⁺ (impurity) might present or vice versa with K⁺ as background ions. The competitive adsorption of these three kinds of ions can yield complicated ICR behaviors.

Rhodamine 6G-based efficient chemosensor for trivalent metal ions (Al3+, Cr3+ and Fe3+) upon single excitation with applications in combinational logic circuits and memory devices

A new rhodamine 6G-based chemosensor (L3) was synthesized and characterized by ¹H, ¹³C, IR and mass spectroscopy studies. It exhibited an excellent selective and sensitive CHEF-based recognition of trivalent metal ions M³⁺ (M = Fe, Al and Cr) over mono and di-valent and other trivalent metal ions with prominent enhancement in the absorption and fluorescence intensity for Fe³⁺ (669-fold), Al³⁺ (653-fold) and Cr³⁺ (667-fold) upon the addition of 2.6 equivalent of these metal ions in the probe in H₂O/CH₃CN (7 : 3, v/v, pH 7.2). The corresponding K_d values were evaluated to be 1.94 × 10^-5 (Fe³⁺), 3.15 × 10^-5 (Al³⁺) and 2.26 × 10^-5 M (Cr³⁺). The quantum yields of L3, [L3-Fe³⁺], [L3-Al³⁺] and [L3-Cr³⁺] complexes in H₂O/CH₃CN (7 : 3, v/v, pH 7.2) were found to be 0.0005, 0.335, 0.327 and 0.333, respectively, using rhodamine-6G as the standard. The LODs for Fe³⁺, Al³⁺ and Cr³⁺ were determined by 3σ methods and found to be 2.57, 0.78 and 0.47 μM, respectively. The cyanide ion snatched Fe³⁺ from the [Fe³⁺-L3] complex and quenched its fluorescence via its ring-closed spirolactam form. Advanced level molecular logic devices using different inputs (2 and 4 input) and a memory device were constructed.

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 CrO₄^2- and 14.91 μM for Cr₂O₇^2-, 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.

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.

Role of endolysosome function in iron metabolism and brain carcinogenesis

Iron, the most abundant metal in human brain, is an essential microelement that regulates numerous cellular mechanisms. Some key physiological roles of iron include oxidative phosphorylation and ATP production, embryonic neuronal development, formation of iron-sulfur clusters, and the regulation of enzymes involved in DNA synthesis and repair. Because of its physiological and pathological importance, iron homeostasis must be tightly regulated by balancing its uptake, transport, and storage. Endosomes and lysosomes (endolysosomes) are acidic organelles known to contain readily releasable stores of various cations including iron and other metals. Increased levels of ferrous (Fe2+) iron can generate reactive oxygen species (ROS) via Fenton chemistry reactions and these increases can damage mitochondria and genomic DNA as well as promote carcinogenesis. Accumulation of iron in the brain has been linked with aging, diet, disease, and cerebral hemorrhage. Further, deregulation of brain iron metabolism has been implicated in carcinogenesis and may be a contributing factor to the increased incidence of brain tumors around the world. Here, we provide insight into mechanisms by which iron accumulation in endolysosomes is altered by pH and lysosome membrane permeabilization. Such events generate excess ROS resulting in mitochondrial DNA damage, fission, and dysfunction, as well as DNA oxidative damage in the nucleus; all of which promote carcinogenesis. A better understanding of the roles that endolysosome iron plays in carcinogenesis may help better inform the development of strategic therapeutic options for cancer treatment and prevention.

One-step Hydrothermal Synthesis of N-doped Fluorescent Carbon Dots from Fermented Rice with Highly Selective Characteristics for Label-free Detection of Fe3+ Ions and as Fluorescent Ink

In our work, N-doped carbon dots (CDs) were synthesized by a facile hydrothermal method with fermented rice as the carbon source. The CDs show bright blue fluorescence, and the maximum emission wavelength was 380 nm with wavelength ranges from 320 to 560 nm. Interestingly, these as-prepared CDs show strong blue photoluminescent properties under the radiation with ultraviolet (UV) light. Moreover, it also exhibits good sensitive fluorescence detection for Fe³⁺ ions; the detection limit is 0.1 μM, which is significant fluorescence quenching based on CDs. Other representative metal ions were further tested to verify their selectivity, which provides a solid underpinning for the practical use in Fe³⁺ ions detection in real samples, e.g. underground water. In addition, the CDs work well as a fluorescent ink and can encrypt and store information.

Determination of Fe(Ⅲ) ion and cellular bioimaging based on a novel photoluminescent silicon nanoparticles

The determination approaches of Fe (Ⅲ) in biological samples were developed by a novel water-soluble silicon nanoparticles (SiNPs). The SiNPs were synthesized by a facile microwave-assisted method, and simultaneously featured strong blue fluorescence (photoluminescence quantum yield: 25.2%), long lifetime (~13.29 ns) and good photo-stability. The fluorescence intensities of SiNPs were gradually quenched with Fe (Ⅲ) concentration increasing from 2.0 to 50 μmol/L. The detection limit of the established method was 0.56 μmol/L and the precision for eleven replicate detections of 20 μmol/L Fe (Ⅲ) was 3.2% (relative standard deviation, RSD). The spiked recoveries were 99.0%-104.5%. Results of the lifetime decay and cyclic voltammetry (CV) evidenced that the electron transfer was responsible for the fluorescence quenching mechanism of SiNPs and Fe (Ⅲ). Moreover, the SiNPs were successfully applied in the determination of Fe(Ⅲ) in different environmental waters and human serum. Finally, the resulting SiNPs exhibited the green fluorescence in HeLa cells as the optical probe.

"Turn-on" fluorescent probes based on Rhodamine B/amino acid derivatives for detection of Fe3+ in water

Five kinds of Fe³⁺ fluorescent probes (RhB-Gly, RhB-Ala, RhB-Try, RhB-Cys, and RhB-His) were synthesized and characterized by NMR and mass spectrometry, based on the "OFF-ON" mechanism of Rhodamine B derivatives. The RhB-His based probe showed remarkable sensing performance toward the detection for Fe³⁺ and showed high selectivity for Fe³⁺ in the presence of other metal ions (such as Fe²⁺, Hg²⁺, Zn²⁺, Ba²⁺, Al³⁺, Co²⁺, Cd²⁺, K⁺, Na⁺, Mn²⁺, Pd²⁺, Pb²⁺, Ca²⁺, Ni²⁺, Cu²⁺, and Ag⁺), in PBS buffer solution (containing 2% of EtOH, pH 7.4, 1.0 mmol/L). The enhancement of the fluorescence was linearly proportional with the concentration Fe³⁺ (from 0 to 20 μmol/L), while the detection limit reached 0.88 μmol/L with a response time of 15 s. The RhB-His probe was successfully applied to investigate real samples and living cell imaging.

An aniline trimer-based multifunctional sensor for colorimetric Fe3+, Cu2+ and Ag+ detection, and its complex for fluorescent sensing of L-tryptophan

The detection of metal ions and amino acids by the aniline oligomer-based receptor has not been reported yet, to the best of our knowledge. In this study, an efficient multifunctional cation-amino acid sensor (CAS) with aniline moiety and chiral thiourea binding site was synthesized by the reaction of aniline trimer and (S)-(+)-1-phenyl ethyl isothiocyanate. CAS can sense Fe³⁺, Cu²⁺, Ag⁺ ions, and L-tryptophan. These results can be recognized by the naked eye. The appropriate pH range for the quantitative analysis of Fe³⁺, Cu^2+, and Ag⁺ by CAS in DMSO/water (30 vol% water) was evaluated. The interaction between CCS and metal ions was analyzed by ¹H NMR titration. The detection limits of CAS for the Cu²⁺, Ag^+, and Fe³⁺ were 0.214, 0.099, and 0.147 μM, respectively. Moreover, the CASCu²⁺ complex can act as a turn-on fluorescence sensor for L-tryptophan. On the contrary, there is no response upon the addition of other amino acids, such as L-histidine, L-proline, L-phenylalanine, L-threonine, L-methionine, L-tyrosine, and L-cystine to CASCu²⁺ complex.

"Turn-on" benzophenone based fluorescence and colorimetric sensor for the selective detection of Fe2+ in aqueous media: Validation of sensing mechanism by spectroscopic and computational studies

A diaminobenzophenone Schiff base derived probe 1, was synthesized and structure elucidation was carried out by spectroscopic studies viz., FT-IR, UV-vis, ¹H, and ¹³C NMR and mass spectrometry. The sensing phenomenon with different metal ions (Cr³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺) was investigated by employing absorption and fluorescence titrations, which demonstrated that probe 1 exhibited selective fluorescent sensing behavior towards Fe²⁺ ion among various other metal ions. The porobes selceteclivity towards Fe²⁺ was also examined by colorimetric assay which revealed a change in the color from light yellow to brown upon addition of Fe²⁺ ion. A remarkable increase in the fluorescence intensity of probe 1 was observed towards Fe²⁺ ion, which was found to be associated with the inhibition of photoinduced electron-transfer (PET) and CN isomerization processes, respectively. The chemosensor exhibited an association constant value of 6.173 × 10⁷ M^-2 as determined by using non-linear least square fit data. Job's plot calculated the binding stoichiometry, and the sensing phenomenon of Fe²⁺ towards the probe was further supported by Density Functional Theory (DFT) calculations and ¹H NMR studies. The detection limit of probe 1 was found to be 0.0363 µM, which is below the permissible limits according to the WHO guideline (5 μM) for Fe²⁺ ions in the drinking water. Furthermore, the practical application of probe 1 was studied by analyzing the content of Fe²⁺ in different water samples.

A highly stable Zn coordination polymer exhibiting pH-dependent fluorescence and as a visually ratiometric and on–off fluorescent sensor

A thermally and chemically stable Zn coordination polymer exhibiting pH-dependent fluorescence behaves as a multi-responsive fluorescent sensor for ratiometric and on–off detection of multiple analytes.

Structures and relative stability of hydrated ferrous ion clusters and temperature effects

Structures of solvated ferrous ion clusters have been investigated in the singlet and quintet spin states of the ferrous ion. Relative stabilities of isomers are also discussed at different temperatures.

Association of transferrin G258A and transferrin receptor A82G polymorphisms with the risk of Parkinson disease in certain area

BACKGROUND

It has been reported that polymorphisms of transferrin (TF) G258A and transferrin receptor (TFR) A82G might be associated with susceptibility to Parkinson disease (PD).

OBJECTIVE

Owing to limitation of sample size and inconclusive results, we conducted a meta-analysis to clarify the association.

METHODS

By searching PubMed, Embase, Chinese National Knowledge Infrastructure, China Biological Medicine Database, and Wanfang Databases, the published articles about studies of the association of the TF G258A, TFR A82G gene polymorphisms with the risk of PD were collected. Q-statistics and I statistics were calculated to examine heterogeneity and summary odds ratios (ORs) and 95% confidence intervals (95%CI) were evaluated the association.

RESULTS

Five studies assessed the relationship between TF G258A and risk of PD. A significant increased protective of A allele and AA genotype was observed in allele model and recessive model (the allele model A vs G: OR = 0.54, 95%CI 0.40-0.72, P < .001; the recessive model AA vs GA + GG: OR = 0.32, 95%CI 0.20-0.52, P < .001). The remaining models of the TF G258A genotype showed no significant association with PD risk, while the protective tendency were increased (the heterozygote model GA vs GG: OR = 0.93, 95%CI 0.61-1.43, P = .75; the homozygous model AA vs GG: OR = 0.47, 95%CI 0.21-1.04, P = .06; the dominant model GA + AA vs GG: OR = 0.75, 95%CI 0.50-1.11, P = .15). There was also a lack of association between TFR A82G polymorphism and PD (the allele model G vs A: OR = 0.92, 95%CI 0.75-1.13, P = .43; the heterozygote model AG vs AA: OR = 1.17, 95%CI 0.79-1.71, P = .43; the homozygous model GG vs AA: OR = 0.91, 95%CI 0.60-139, P = .66; the dominant model AG + GG vs AA: OR = 1.05, 95%CI 0.73-1.49, P = .81; the recessive model GG vs AG +AA: OR = 0.80, 95%CI 0.59-1.09, P = .16).

CONCLUSION

Our study suggests that TF G258A polymorphism may be associated with PD, while TFR A82G polymorphism may not contribute to PD based on the current evidence.

Luminescent Conductive Columnar π-Gelators for Fe(II) Sensing and Bio-Imaging Applications

The high demand and scarcity of luminescent, photoconductive, and transparent gels necessitate its finding as they are potential components in photonic devices such as solar cell concentrators where optical losses via scattering and reabsorption require to be minimized. In this direction, we have reported highly transparent, blue luminescent as well as photoconductive gels exhibiting the hole mobility of 10^-3 cm²/V s at ambient temperature as investigated by the time-of-flight technique. The π-driven self-standing supergels were formed using triazole-modified phenylene-vinylene derivatives as gelators in a nonpolar solvent. Different microscopic studies revealed its entangled network of interwoven fibrilar self-assembly and anisotropic order in the gel state. Supramolecular assembly of xerogels, studied by small- and wide-angle X-ray scattering (SAXS/WAXS) suggesting their local columnar hexagonal (Col_h) superstructure, is beneficial for conducting gels. Rheological measurements direct the stiffness and robustness of the organogels. In addition, the gelators were developed as a sensing platform for the ultrasensitive detection of Fe(II) ions at ppb level. ¹H nuclear magnetic resonance (NMR) titrimetric studies revealed that the interaction of the H-atom of triazole units with Fe(II) is responsible for quenching of blue fluorescence. Also, one of the gelators was successfully applied in bio-imaging using the pollen grains of the Hibiscus rosa-sinensis plant.

Ever-Evolving Identity of Magnetic Nanoparticles within Human Cells: The Interplay of Endosomal Confinement, Degradation, Storage, and Neocrystallization

Considerable knowledge has been acquired in inorganic nanoparticles' synthesis and nanoparticles' potential use in biomedical applications. Among different materials, iron oxide nanoparticles remain unrivaled for several reasons. Not only do they respond to multiple physical stimuli (e.g., magnetism, light) and exert multifunctional therapeutic and diagnostic actions but also they are biocompatible and integrate endogenous iron-related metabolic pathways. With the aim to optimize the use of (magnetic) iron oxide nanoparticles in biomedicine, different biophysical phenomena have been recently identified and studied. Among them, the concept of a "nanoparticle's identity" is of particular importance. Nanoparticles' identities evolve in distinct biological environments and over different periods of time. In this Account, we focus on the remodeling of magnetic nanoparticles' identities following their journey inside cells. For instance, nanoparticles' functions, such as heat generation or magnetic resonance imaging, can be highly impacted by endosomal confinement. Structural degradation of nanoparticles was also evidenced and quantified in cellulo and correlates with the loss of magnetic nanoparticle properties. Remarkably, in human stem cells, the nonmagnetic products of nanoparticles' degradation could be subsequently reassembled into neosynthesized, endogenous magnetic nanoparticles. This stunning occurrence might account for the natural presence of magnetic particles in human organs, especially the brain. However, mechanistic details and the implication of such phenomena in homeostasis and disease have yet to be completely unraveled.This Account aims to assess the short- and long-term transformations of magnetic iron oxide nanoparticles in living cells, particularly focusing on human stem cells. Precisely, we herein overview the multiple and ever-evolving chemical, physical, and biological magnetic nanoparticles' identities and emphasize the remarkable intracellular fate of these nanoparticles.

A novel pyrazole bearing imidazole frame as ratiometric fluorescent chemosensor for Al3+/Fe3+ ions and its application in HeLa cell imaging

New pyrazole bearing imidazole derivative was successfully synthesized and thoroughly characterized by various spectroanalytical techniques. The sensor DIBI shows a highly selective and sensitive fluorescent response with the addition of Al³⁺/Fe³⁺ ions in acetonitrile-water mixture. The strong fluorescent molecule exhibits a notable ratiometric emissions at 462 nm and 470 nm for Al³⁺ and Fe³⁺ ions, respectively (λ_ex = 280 nm). Job's plot studies conclude that the coordination between DIBI with Al³⁺/Fe³⁺ was 1:1 binding stoichiometry. The limit of detection of DIBI with Al³⁺/Fe³⁺ was calculated as 2.12 × 10^-7 M and 1.73 × 10^-6 M, respectively. The TD-DFT calculations further supported the photonics performances of the free probe and its complexes. The reversibility and reusability of the sensor molecule are studied using EDTA. The probe was used to track Al³⁺/Fe³⁺ in cancer cells via fluorescence microscopy.

A cystine-based dual chemosensor for fluorescent-colorimetric detection of CN- and fluorescent detection of Fe3+ in aqueous media: Synthesis, spectroscopic, and DFT studies

A new dual-responsive chiral cystine based chemosensor, Cys(cou)₂, has been designed and characterized by ¹H NMR, ¹³C NMR, FT-IR, UV-vis as well as elemental analysis. This sensor exhibited an excellent response towards Fe³⁺ and CN^- with high selectivity and sensitivity by fluorescence turn-off mechanism. The binding mode of Cys(cou)₂ with Fe³⁺, and CN^- was confirmed by ESI-MS, ¹H NMR, and fluorescence titration and also quantum chemical calculation. These results showed that the stoichiometric ratio of Cys(cou)₂-Fe³⁺ and Cys(cou)₂-CN is 1:1 and 1:3 in DMSO/Tris aqueous buffer (1:1, v/v), respectively. The linear relationship of the Stern-Volmer plot illustrates the static quenching mechanism at different concentrations. The detection limit (LOD) and binding constant (K_a) for Fe³⁺ and CN^- are 0.029 μM, 1.28 × 10⁴ and 0.51 μM, 9.94 × 10⁶, respectively. Moreover, Cys(cou)₂ can act as a colorimetric sensor for CN^- in DMSO with the color change from colorless to yellow.

A naphthylamide based fluorescent probe for detection of Al3+, Fe3+, and CN- with high sensitivity and selectivity

A naphthylamide based fluorescent chemosensor, N,N'-(1,2-phenylene)bis(1-hydroxy-2-naphthamide) (H₄L), for detection of Fe³⁺ and Al³⁺ cations as well as CN^- anion is reported. This compound has been synthesized by a novel and facile synthetic method with high yield and characterized by FT-IR, ¹H NMR, elemental analysis, and UV-Vis spectroscopy. It could detect Fe³⁺ and Al³⁺ ions in different media with different excitation and emission wavelengths. In DMSO solution, H₄L showed selective ON-OFF quenching of its 451 nm emission in the presence of Fe³⁺. On the other hand, in DMF solution, H₄L exhibited selective OFF-ON fluorescence upon the addition of Al³⁺, the intensity at 429 nm increases drastically by 24-fold. Also, among the anions, the probe can selectively distinguish CN^- by deprotonation of OH and NH groups, as proved by ¹H NMR titration. TD-DFT calculation supports the UV-Vis and fluorescence measurements of the chemosensor.

Colorimetric Metal Sensing of Fe3+ and Cr3+ and Photophysical and Electrochemical Studies Based on Benzo[4,5]thiazolo[3,2-a]pyrimidine-3-carboxylate and Its Derivatives

Benzo[4,5]thiazolo[3, 2-a]pyrimidine-3-carboxylate derivatives (4a-i) containing electron-donor and electron-acceptor groups with remarkable photophysical and electrochemical properties were synthesized. The changes in absorption properties of compound 4a in the presence of various cations were evaluated. Compound 4a can act as a colorimetric sensor for highly sensitive and selective detection of Fe³⁺ and Cr³⁺in acetonitrile solvent. Using measurements of absorbance intensity, the binding constants for the 4a + Fe³⁺ complex and 4a + Cr³⁺ complex were found to be 1.958 × 10⁸ and 1.5442 × 10⁷ M^-1 with lower detection limits of 52 and 110 nM, respectively. ¹H NMR titrations, Fourier transform infrared (FTIR) studies, electrospray ionization (ESI)-mass spectra, and Job's plots were used to verify the mechanism of the specific reaction and colorimetric sensing of 4a + Fe³⁺ and 4a + Cr³⁺. The application of compound 4a for the determination of Fe³⁺ in spiked samples of iron tablets in different environmental water samples showed a satisfactory result with good recovery.