Characterization of Al3+-toxicity responses and molecular mechanisms underlying organic acid efflux in Vigna mungo (L.) Hepper.

Aluminium (Al3+) toxicity in acidic soils poses a significant challenge for crop cultivation and reduces crop productivity. The primary defense mechanism against Al3+ toxicity involves the activation of organic acid secretion. In this study, responses of 9 Vigna mungo cultivars to Al3+ toxicity were investigated, with a particular emphasis on the root system and crucial genes involved in Al3+ tolerance using molecular cloning and expression analysis. Sensitive blackgram-KM2 cultivars exposed to 100-µM Al3+ toxicity for 72 h exhibited a root-growth inhibition of approximately 66.17%. Significant loss of membrane integrity and structural deformative roots were found to be the primary symptoms of Al3+ toxicity in blackgram. MATE (Multidrug and Toxic Compound Extrusion) and ALS3 (Aluminium Sensitive 3) genes were successfully cloned from a sensitive blackgram cv KM2 with phylogenetic analysis revealing their evolutionary relationship to Vigna radiata and Glycine max. The MATE gene is mainly localized in the plasma membrane, and highly expressed under Al3+, thus suggesting its role in transports of citrate-Al3+ complexes, and detoxifying Al3+ within plant cells. In addition, ALS3 was also induced under Al3+ toxicity, which codes the UDP-glucose transporter and is required for the maintenance of ions homeostasis. In summary, this study highlights the understanding of Al3+ toxicity and underlying molecular mechanisms linked to the efflux of organic acid in blackgram, ultimately aiding the framework for the development of strategies to enhance the resilience of blackgram and other pulse crops in Al-rich soils.

Solvent-Selective Fluorescence Sensing of Mg2+ and Al3+ Ions by Pincer-Type NNO Schiff Base Ligand: An Experimental and DFT Optimized Approach.

A newly developed dual-functional fluorescence sensing probe (phenylhydrazinyl pyridine) Schiff base (SB) has been designed with good selectivity for distinguishing Mg2+ and Al3+ metal ions in different solvent solutions. SB exhibits quick and visual turn-on fluorescence enhancement in response to Mg2+ and Al3+ detection. The addition of Mg2+ in ACN-HEPES buffer (1 : 1, v/v, pH 7.2) at (λmax=390 nm) and Al3+ in MeOH-HEPES buffer (1 : 1, v/v, pH 7.2) at (λmax=360 nm) resulted in significant enhancement of fluorescence, up to 7-9 times. These low detection limits of 7.1×10-6 M (7.1 µM) and 5.15×10-7 M (0.51 µM) for Mg2+ and Al3+, respectively, have been achieved by this solvent-controlled platform. Due to the sensing potential towards Mg2+, the probe was utilized as an imaging material for breast cancer cells. 1H-NMR studies were utilized to explore SB's sensing mechanism through turn-on fluorescence. Density functional theory (DFT) calculations were utilized to validate optimized SB and its intricate geometries, which govern the sensing mechanism in the solvent environment. Such a probe has extensive potential applications in bioimaging and the assessment of the quality of wastewater.

A Novel Multi-Functional Fluorescence Probe for the Detection of Al3+/Zn2+/Cd2+ and its Practical Applications.

A novel multi-functional fluorescence probe HMIC based on hydrazide Schiff base has been successfully synthesized and characterized. It can distinguish Al3+/Zn2+/Cd2+ in ethanol, in which fluorescence emission with different colors (blue for Al3+, orange for Zn2+, and green for Cd2+) were presented. The limits of detection of HMIC towards three ions were calculated from the titration curve as 7.70 × 10- 9 M, 4.64 × 10- 9 M, and 1.35 × 10- 8 M, respectively. The structures of HMIC and its complexes were investigated using UV-Vis spectra, Job's plot, infrared spectra, mass spectrometry, 1H-NMR and DFT calculations. Practical application studies have also demonstrated that HMIC can be applied to real samples with a low impact of potential interferents. Cytotoxicity and cellular imaging assays have shown that HMIC has good cellular permeability and potential antitumor effects. Interestingly, HMIC can image Al3+, Zn2+ and Cd2+ in the cells with different fluorescence signals.

Method for highly selective, ultrasensitive fluorimetric detection of Cu2+ and Al3+ by Schiff bases containing o-phenylenediamine and o-aminophenol.

Schiff base probes (1 and 2) made from o-phenylenediamine and o-aminophenol were appeared as highly selective fluorimetric chemosensor of Cu2+ and Al3+ ions respectively. Strong fluorescence emission of probe 1 at 415 nm (excitation at 350 nm) was instantly turned off on addition of Cu2+. Very weak fluorescence of probe 2 at 506 nm (excitation at 400 nm) was immediately turned on specifically by Al3+. Job's plot and ESI-MS results suggested 1:1 molar stoichiometric ratio of metal ion and probe in their respective complexes. Probe 1 and 2 had demonstrated very low detection limit (9.9 and 2.5 nM respectively). Binding of Cu2+ with probe 1 was found chemically reversible on addition of EDTA, while complexation between Al3+ and probe 2 was not reversible. On the basis of density functional theory (DFT) and spectroscopic results, probable mode of sensing of the metal ions by the probes were proposed. Quenching of the fluorescence of probe 1 by Cu2+ was attributed to the extensive transfer of charge from the probe molecule to paramagnetic copper ion. Whereas, in the Al3+-complex of probe 2, photo-induced electron transfer (PET) process from the imine nitrogen to salicylaldehyde moiety was restricted and thereby the weak emission intensity of probe 2 was enhanced significantly. Effective pH range of sensing the metal ions by probe 1 and 2 were 4 to 8 and 6 to 10 respectively. Probe 1 was also applied in the design of a logic gate for Cu2+ detection. Moreover, probe 1 and 2 was also used in water sample analysis for quantitative estimation of Cu2+ and Al3+ respectively.

Development of an AIE-active fluorescent probe for the simultaneous detection of Al3+ and viscosity and imaging in Alzheimer's disease model.

Alzheimer's disease is associated both with imbalances in Al3+ production and changes in viscosity in cells. Their simultaneous measurement could therefore provide valuable insights into Alzheimer's disease pathology. Their simultaneous measurement would therefore be of great value in investigating the pathological mechanism of Alzheimer's disease. We designed a fluorescent probe YM2T with AIE effect that is capable of selectively responding to Al3+ by fluorescence colormetrics and to viscosity by fluorescence "turn on" modes. Additionally, Al3+ and viscosity were simultaneously detected in PC12 cells using the low cytotoxic probe YM2T via blue and green fluorescence channels. More importantly, the YM2T probe was used to image mice with AD. Hence, the YM2T probe shows potential as a useful molecular instrument for studying the pathological impact of Al3+ and viscosity.

A red fluorescent carbon dots with good water solubility for rapid detection of Al3+ in actual samples.

We developed a facile strategy for the fabrication of red fluorescent carbon nanodots (R-CDs) and demonstrated their applications for Al3+ sensing. Red-emission carbon dots (CDs) were synthesized using a simple hydrothermal treatment with citric acid and urea as precursors, manifesting intriguing red-emission behaviour at 610 nm. With increasing Al3+ concentration, the fluorescence band at 610 nm decreased gradually. Monitoring the intrinsic fluorescence variation (I610nm ), as-prepared CDs were developed as an effective platform for fluorescent Al3+ sensing, with a linear range of 0.5-60.0 µM and a detection limit of 3.0 nM. More importantly, R-CDs have been applied successfully to the analysis of Al3+ in actual samples with satisfactory recoveries in the range 97.12-102.05%, which indicated that obtained CDs could be implemented as an effective tool for the identification and detection of Al3+ in actual samples.

Pyrene Based Schiff Base for Cascade Fluorescent "On-Off" Detection of Aluminium(III) and Fluoride ions and its Applications in Live Cells Imaging.

An easy-to-prepare pyrene-based Schiff base PNZ was synthesized by condensing equimolar amount of 1-pyrenebutyric hydrazide with 2-hydroxy-naphthaldehyde, and employed as a fluorescent chemosensor for in-situ cascade detection of aluminium (Al3+) and fluoride (F-) ions. In DMSO:H2O (1:1, v/v), the weakly emissive PNZ showed a significant fluorescence enhancement at 455 nm selectively upon the addition of Al3+ due to the complexation-induced formation of a pyrene excimer. Schiff base PNZ and Al3+ formed a complex in 2:1 binding ratio with the estimated binding constants of K1:1 = 9826.01 M-1 and K2:1 = 3188.49 M-1. The sensing mechanism was explored by performing quantum mechanical calculations and 1H NMR titration of PNZ with Al3+. The in-situ formed PNZ-Al3+ complex species enabled the fluorescent turn-off detection of F-. Using PNZ and PNZ-Al3+, the concentrations of Al3+ and F- ions can be detected down to 2.89×10-7 M and 1.88×10-7 M, respectively. The cytotoxicity of the PNZ and its ability to bioimage Al3+ and F- ions was examined in the human cervical cancer cell line. Finally, the receptor PNZ was applied for the quantification of Al3+ and F- ions in various real samples, such as tap water, river water, rainwater, mouthwash, and toothpaste.

Dual-mode fluorescent and colorimetric sensing of thiourea and aluminum ion in natural water based on CuO nanoparticles.

CuO nanoparticles with good water solubility and uniform particle size were successfully prepared. Interestingly, the oxidase-like activity of CuO NPs was continuously enhanced by the addition of thiourea (TU), and the enzyme activity was further enhanced by the addition of aluminum ion (Al3+). By systematically exploring and optimizing the experimental conditions, including the key parameters such as temperature, reaction time, and pH, a fluorescence-colorimetric dual-mode sensing system based on CuO nanoparticles was constructed. The detection range of TU and Al3+ were 1-100 µM and 1-100 µM, respectively, and the selectivity and precision of detection were further improved. In addition, the catalytic mechanism of CuO NPs as oxidase-like catalysts and the specific process in the reaction were investigated. Finally, the nano-sensing system was successfully applied to the analysis of three real environmental samples, namely, tap water, lake water and river water, which provided an effective new strategy for the future development of nano-sensing technology for TU and Al3+.

A cotton swab platform for fluorescent detection of aluminum ion in food samples based on aggregation-induced emission of carbon dots.

A novel portable cotton swab based on nitrogen-doped carbon dots (NCDs) for Al3+ detection was constructed for the first time. NCDs with bright green fluorescence were prepared by hydrothermal method with phenylhydrazine hydrochloride and 3-hydroxy-2-naphthoic acid hydrazide as precursors. The surface of NCDs was exposed to abundant functional groups (such as amino, carboxyl, hydroxyl, etc.), which was helpful for the formation of complexes between NCDs and Al3+. In the presence of Al3+, the aggregation of NCDs obviously induced their fluorescence enhancement due to the aggregation-induced emission (AIE) of NCDs. Furthermore, the quantum yield (QY) of NCDs was enhanced by 12 times with Al3+, and the fluorescence lifetime was increased by 7.54 ns. The fluorescence intensity was linearly correlated with the concentration of Al3+ (2.5-300 µM), and the limit of detection was 0.76 µM. Moreover, for the portable way, cotton swabs were successfully employed to construct the sensors for the detection of Al3+ in food samples. This proposal has potential for the application in food analysis.

Fluorescent and colorimetric dual-mode recognition of Al3+ in tablets based on chrome azurol S and pH-switchable boron, nitrogen co-doped carbon dots.

The synthesis and characterization of pH-sensitive boron and nitrogen co-doped CDs (B, N-CDs) is reported. The fluorescence of B, N-CDs exhibited pH-responsive behavior within the range pH 3.0-6.0, attributed to their controlled aggregation and disaggregation. Interestingly, the fluorescence of B, N-CDs was quenched by the inner filter effect from chrome azurol S (CAS). With the subsequent addition of Al3+, the fluorescence of B, N-CDs was restored due to the formation of blue Al3+-CAS and B, N-CDs-Al3+ complexes. Consequently, a fluorescent and colorimetric dual-mode sensor for Al3+ detection was developed. The proposed sensor enabled Al3+ detection in the ranges and limits of detection of 3.75-22.5 µM and 2.67 µM for the fluorescent mode and 5-20 µM and 4.8 µM for the colorimetric mode, respectively. Furthermore, the efficacy of the sensor was validated through successful detection of Al3+ in tablet samples. The obtained B, N-CDs promised the application in acid condition and the proposed sensor is expected to be applied to in situ on-line detection of Al3+.

Knockdown of Adenosine 5'-Triphosphate-Dependent Caseinolytic Protease Proteolytic Subunit 6 Enhances Aluminum Tolerance in Peanut Plants (Arachis hypogea L.).

Aluminum (Al3+) toxicity in acidic soils reduces root growth and can lead to a considerable reduction in peanut plants (Arachis hypogea L.). The caseinolytic protease (Clp) system plays the key role in abiotic stress response. However, it is still unknown whether it is involved in peanut response to Al3+ stress. The results from this study showed that Adenosine 5'-triphosphate (ATP)-dependent caseinolytic protease proteolytic subunit 6 (AhClpP6) in peanut plants was involved in the Al3 stress response through its effects on leaf photosynthesis. The AhClpP6 expression levels in the leaf and stem significantly increased with the Al3+ treatment times. Knockdown AhClpP6 peanut lines accumulated significantly more Al3+ when exposed to Al3+ stress, which reduced leaf photosynthesis. Furthermore, in response to Al3+ treatment, knockdown of AhClpP6 resulted in a flattened shape of chloroplasts, disordered and flattened thylakoid, and accumulating more starch grains than those of the wild-type (WT) peanut lines. Taken together, our results suggest that AhClpP6 regulates Al3+ tolerance by maintaining chloroplast integrity and enhancing photosynthesis.

"Dual- Engineering" Strategy to Regulate NH4 V4 O10 as Cathodes for High-Performance Aqueous Zinc Ion Batteries.

Aqueous zinc ion batteries (AZIBs) have attracted attention as a promising candidate for secondary battery energy storage due to their safety and environmental benefits. However, the vanadium-based cathode material NH4 V4 O10 has the problem of structural instability. In this paper, it is found by density functional theory calculation that excessive NH4 + located in the interlayer will repel the Zn2+ during the process of Zn2+ insertion. This results in the distortion of the layered structure, further affects the diffusion of Zn2+ and reduces the reaction kinetics. Therefore, part of the NH4 + is removed by heat treatment. In addition, the introduction of Al3+ into the material by hydrothermal method is able to further enhance its zinc storage properties. This dual-engineering strategy shows excellent electrochemical performance (578.2 mAh g-1 at 0.2 A g-1 ). This study provides valuable insights for the development of high performance AZIBs cathode materials.

Anthracene scaffold as highly selective chemosensor for Al3+ and its AIEE activity.

Fluorescent chemosensor, 3-(Anthracen-2-yliminomethyl)-benzene-1,2-diol (ANB) has been synthesized by one-step condensation of 2-aminoanthracene and 2,3-dihydroxybenzaldehyde and characterized using 1H-NMR, FT-IR and Mass spectroscopic techniques. The probe ANB was found to be an efficient 'turn-on' fluorescence chemosensor for the selective detection of Al3+ ion over other metal ions in an aqueous solution. The chemosensor exhibits ~ 27-fold enhancement of emission intensity in presence of Al3+ ion. Fluorescence quantum values for ANB and (Al3+-ANB)-complex are 0.004 and 0.097, respectively. In addition, the binding constant and the limit of detection were found to be 1.22 × 104 M-1 and 0.391 µM, respectively. The chemosensor ANB binds to Al3+ ions in 2:1 stoichiometric ratio which was supported by Job's plot, 1H-NMR titration and florescence titration. Fluorescence reversibility of the sensor complex was well established by adding EDTA in the same condition and a molecular INHIBIT logic gate was fabricated using this reversible nature of the sensor complex. Additionally, the chemosensor ANB shows a novel aggregation-induced enhanced emission phenomenon, where the aggregate hydrosol of ANB shows enhance emission intensity.

Hydrazide Schiff base Compound Containing Triphenylphosphonium Units for Fluorescence Sensing of Al3+ and its real Sample Applications.

Al3+ excess in the body can cause many diseases. The development of chemosensors for the detection of Al3+ is therefore highly desirable. A hydrazide Schiff base compound containing triphenylphosphonium units (ER) was prepared and used as fluorescence turn-on sensor for the sensing of Al3+. Detection of Al3+ among various metals has been achieved successfully through the formation of Al3+-ligand coordination complexes. To detect Al3+, the "turn on" property of the fluorogenic chemosensor was investigated. Fluorescence sensing studies were carried out in CH3OH-Water (v/v, 9/1, pH 7.0) at λem = 528 nm. The LOD for sensing of Al3+ was found to be 0.129 µM. Using Job's graph, the stoichiometric ratio of ER- Al3+ was determined to be 1:1. The binding constant was determined to be 1.7 × 107 M-1 between Al3 + and the chemosensor ER. Finally, the determination of Al3+ in real herbal teas was carried out by using the sensing function of the chemosensor ER.

'AIE + ESIPT' Active 2-hydroxy-naphthalene Hydrazone for the Fluorescence Turn-on Sensing of Al3.

The aggregation-induced emission (AIE) behaviour of an easy-to-prepare Schiff base 2-hydroxy-naphthalene hydrazone (L) was explored in mixed DMSO/HEPES medium by selecting DMSO as a good solvent, whereas HEPES buffer (H2O, 10 mM, pH 7.4) as a poor solvent. The weakly fluorescent L in pure DMSO showed a fluorescence enhancement at 532 nm upon increasing the fraction of HEPES above 70% because of the self-aggregation of L and excited state intramolecular proton transfer (ESIPT) process. The AIE luminogen (AIEgen) L was applied for the sensing of metal ions in HEPES buffer (5% DMSO, 10 mM, pH 7.4). Among the fourteen different metal ions (Cu2+, Co2+, Ni2+, Mn2+, Mg2+, Fe3+, Fe2+, Zn2+, Cd2+, Hg2+, Pb2+, Al3+, Cr3+), AIEgen L showed a selective fluorescence enhancement at 435 nm in the presence of Al3+ without disturbing the fluorescence intensity at 532 nm due to the chelation-enhanced fluorescence effect (CHEF). The detection limit of 20 nM was estimated by performing the fluorescence titration of AIEgen L with Al3+. The reversibility of the Al3+ selective AIEgen L was demonstrated by adding a strong chelating agent EDTA. Finally, the practical utility of AIEgen L was validated by quantifying Al3+ in river and tap water samples.

Novel Flavonoid Photoswitchable "Turn-On" Fluorescent Chemosensors: Synthesis of Bromo Flavonols for Nanomolar Aluminum Ion Detection and Cellular Imaging, among Other Applications.

Aluminum (Al), a non-essential element in living systems, can potentially cause chronic toxicity. Therefore, it is crucial to have a specific and sensitive method for detecting Al3+ in order to assess its risk to life. In this study, we designed and synthesized a novel fluorescent probe (IV) based on bromoflavonol. Upon binding to Al3+, probe IV exhibits a blue shift in emission and enhanced fluorescence, making it suitable for Al3+ detection. Our UV-Vis absorption and fluorescence emission spectra demonstrate that probe IV has high selectivity and sensitivity towards Al3+ while being immune to interference from other metal ions. Through fluorescence titration, we determined that the detection limit (LOD) of probe IV for Al3+ is 1.8 × 10-8 mol/L. Job's curve and 1 H NMR titration further confirmed a 1:1 binding stoichiometry between probe IV and Al3+. Additionally, using DFT (Density Functional Theory), we calculated the energy gap difference between IV and IV + Al3+ and found that the complex formed by probe IV and Al3+ is more stable than IV alone. We successfully detected Al3+ in tap water and river water from the middle regions of the Han River, achieving recoveries of over 96% using this probe. This demonstrates its potential for quantitative detection of Al3+ in environmental water samples. Moreover, we successfully used the probe for imaging Al3+ in MG63 cells, suggesting its potential application in biological imaging.

A New Azo-Schiff Base Dual-mode Chemosensor: Colorimetric Detection of Cobalt Ions and Fluorometric Detection of Aluminum Ions in Aqueous Ethanol Solution.

A new Azo-Schiff base ligand (H2L) was designed and synthesized as a cation chemosensor. The chemosensor H2L as dual chemosensor showed selective fluorescence recognition of Al3+ with a noticeable fluorescence enhancement and colorimetric detection of Co2 + in aqueous ethanol solution. The H2L exhibits a linear response toward Al3+ ions in the concentration range of 1.91 × 10-8 M to 4.8 × 10-6 M with a limit of detection of 1.91 × 10-8 M. The sensing mechanism of sensor H2L toward Al3+ was investigated by 1H NMR and IR spectroscopies. Fluorescence switch based on the control of EDTA and Al3+ proved H2L could act as a reversible chemosensor. The molecular structure of [NiL] complex has been determined by X-ray crystallography.

A Simple Schiff Base as Fluorescent Probe for Detection of Al3+ in Aqueous Media and its Application in Cells Imaging.

A novel fluorescence probe for the detection of Al3+ was developed based on methionine protected gold nanoclusters (Met-AuNCs). A fluorescent Schiff base (an aldimine) is formed between the aldehyde group of salicylaldehyde (SA) and the amino groups of Met on the AuNCs, and developed for selective detection of Al3+ in aqueous solution. Al3+ can strongly bind with the Schiff base ligands, accompanied by the blue-shift and an obvious fluorescence emission enhancement at 455 nm. The limits of detection (LODs) of the probe are 2 pmol L-1 for Al3+. Moreover, the probe can successfully be used in fluorescence imaging of Al3+ in living cells (SHSY5Y cells), suggesting that the simple fluorescent probe has great potential use in biological imaging.

Fluorescence Turn-on Detection of Alkaline Phosphatase Activity and Al3+ Using Vitamin B6 Cofactor Conjugated GSH Capped Mn-doped ZnS Quantum Dots.

The glutathione (GSH) functionalized Mn-doped ZnS quantum dots (GSH_Mn_ZnS QDs) was conjugated with pyridoxal 5'-phosphate (PLP). The -CHO group of vitamin B6 cofactor PLP interacted with the -NH2 group of GSH functionalized Mn_ZnS QDs. The conjugation of PLP quenched the fluorescence emission of GSH_Mn_ZnS QDs at 601 nm. Addition of alkaline phosphatase (ALP) catalytically dephosphorylated the PLP into pyridoxal that restored the fluorescence emission of GSH_Mn_ZnS QDs. With a sensitivity of 0.035 U/L, the PLP conjugated GSH_Mn_ZnS QDs was applied to quantify ALP activity in human serum and plasma. Further, the developed nanoprobe PLP conjugated GSH_Mn_ZnS QDs was also applied to detect Al3+. The complexation-induced fluorescence enhancement was observed at 492 nm upon the interaction of Al3+ with the PLP conjugated GSH_Mn_ZnS QDs. Without any interference from other tested metal ions, this nanoprobe can be employed to detect Al3+ down to 2.30 µM.

Fabrication of a New Coumarin Based Fluorescent "turn-on" Probe for Distinct and Sequential Recognition of Al3+ and F- Along With Its Application in Live Cell Imaging.

A new coumarin based fluorescent switch PCEH is fabricated which displays high selective sensing towards Al3+ among other metal cations at physiological pH. On gradual addition of Al3+, PCEH shows a brilliant "turn-on" emission enhancement in MeOH/H2O (4/1, v/v) solution. This new fluorescent switch is proven to be a reversible probe by gradual addition of F- into the PCEH-Al3+ solution. Detection limit as well as binding constant values are calculated to be in the order of 10-9 M and 104 M-1 respectively. We have also explored its potential as a biomarker in the application of live cell imaging using breast cancer cells (MDA-MB-231 cell).