Search

Voltammetric sensor using a symmetrical derivative of anthrone3 (1,7-diamino-3,9-dibutyl benzo[1,2,3-de:4,5,6-d’e’]diquinoline-2,8(3H,9H)-dione) (SPE-A) has been developed as a probe for Hg(II) ions. Performance of the probe as screen-printed electrode modified with the receptor (SPE-A) has been compared with anthrone3 in solution phase, using 1:1 water-acetonitrile solvent system. Anthrone3 displayed an electrochemically quasi-reversible nature in voltammograms with both the systems and is presented as a novel disposable voltammetric sensor for mercury ions. Upon interaction with cations, both the electrode systems showed sensitivity towards Hg2+ ions with a lower detection limit of 0.61 µM. The magnitude of the voltammetric current with the SPE-A exhibited three times the current obtained with a bare glassy carbon electrode (GC). Kinetic performance of the SPE-A electrode is better than the GC electrode. The morphological studies indicate reusability of the electrodes.

This communication focusses on the synthesis of red fluorescent lysozyme cocooned gold nanoclusters (Lyso-AuNCs) that have been successfully applied for the selective and specific recognition of the vitamin B cofactor pyridoxal-5′-phosphate (PLP). The red fluorescence of Lyso-AuNCs showed remarkable color change to yellow upon conjugation with PLP due to the formation of a Schiff base between the free -NH present in the lysozyme and the -CHO group of PLP. The developed PLP conjugated Lyso-AuNCs (PLP_Lyso-AuNCs) was applied for the selective turn-on recognition of Zn ions in aqueous medium. The yellow fluorescence of PLP_Lyso-AuNCs exhibited significant enhancement at 475 nm in the presence of Zn producing bluish-green fluorescence attributed to the complexation-induced aggregation of nanoclusters. The nanoprobe exhibits nanomolar limit of detection for Zn ions (39.2 nM) and the practicality of the nanoprobe was validated in various environmental water samples and biological plasma, urine, and beetroot extract, with fairly good recovery percent. Also, the system was successfully implemented for the intracellular detection and monitoring of Zn in live HeLa cells. [ABSTRACT FROM AUTHOR]

Biogenic amines are important indicators of food spoilage and quality. Food safety is significantly influenced by biogenic amines such as Putrescine and Cadaverine, produced by microbes during food spoilage. Herein, a colorimetric probe for detecting Putrescine and Cadaverine based on a chemo-dosimeter strategy has been proposed. The probe L 1 irreversibly binds with Putrescine and Cadaverine through an aza-Michael addition reaction in which the dicyanomethyl group of the probe is substituted by the primary amine group from the biogenic amines. This chemical reaction rapidly changes color from colorless to pale green. The probe could detect Putrescine and Cadaverine in trace levels of 52 nM and 18 nM, without much interference from other common biogenic amines. The binding mechanism of probe L 1 with biogenic amines was confirmed using 1 H NMR, IR, and DFT studies. The detection procedure is made portable and affordable by using a smartphone camera to capture colorimetric changes and convert them into RGB coordinates. Test paper strips coated with the probe were developed to illustrate its real-world analytical application. The potential application of probe L 1 in real samples was demonstrated using in-vivo models of Prawn and Beef using test paper strips. Probe L 1 showed satisfactory performance for detecting Putrescine and Cadaverine in the vapor phase., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Declaration of competing interest The authors declare that there are no competing financial or personal interests that could have influenced the results presented in this manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

The manuscript presents the synthesis of a new di-chromene Schiff base (COM-CH) by combining 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide and 4-oxo-4H-chromene-3-carbaldehyde, and its characterization using various analytical techniques. The probe COM-CH functional group contains a hard donor atom that selectively complexes with Th 4+ ions. This report investigated COM-CH's sensing ability towards Th 4+ chromogenic and fluorogenic methods in ACN: H 2 O (8:2, v/v) with Th 4+ ions. The COM-CH-Th 4+ complex was excited at 430 nm, resulting in a bright emission band at 475 nm with a 45 nm Stokes shift. The COM-CH probe demonstrated the highest performance at pH 4.0 to 8.0, with a sensitivity of 18.7 nM. The complex formation of COM-CH with Th 4+ was investigated using NMR, FTIR spectrometry, and density functional theory calculations. The COM-CH and Th 4+ are bound with 2:1 stoichiometry and an association constant of 1.92 × 10 8 M -2 . The probe's performance enabled the analysis of monazite sand and water samples for Th 4+ content. The probe successfully detected Th 4+ content in Caenorhabditis elegans, marking the first Th 4+ detection in animal models., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

A newly synthesized Schiff's base 2-(2-([2,2'-bithiophen]-5-ylmethylene)hydrazinyl)benzothiazole ( BT ) was obtained from the condensation reaction between 2-hydrazinobenzothiazole and 2,2-bithiophene-5-carboxaldehyde. The prepared probe BT was subjected to a confirmation of the structural arrangement through NMR, FTIR, ESI-HRMS, and single-crystal XRD spectral analysis. The BT colorimetric sensor showed selectivity and sensitivity toward the cyanide (CN - ) ion over other common anions such as ClO 4 - , Cl - , Br - , F - , I - , NO 2 - , OH - , HSO 4 - , and H 2 PO 4 - in a partial aqueous system CH 3 CN/H 2 O (8:2, v/v). The probe BT detects CN - with the lowest detection range as low as 1.33 × 10 -8 M (3.59 ppm); in comparison to that given by WHO guidelines, it is significantly lower. The stoichiometric interaction between the probe BT and analyte CN - was found to be 1:1 (BT/CN - ) binding mode using Jobs plot, and further association binding affinity was calculated to be 6.64 × 10 -3 M -1 . Additionally, these results were further supported by the FTIR and DFT calculations, as well as the 1 H NMR titration analysis, which complemented the binding data. The sensor probe BT was successfully employed in a cotton swab test kit approach and also in smartphone-assisted applications for the determination of CN - ions. Finally, the outstanding sensing properties of probe BT aided the quantitative detection of CN - ions, and it could be further applied to a variety of food samples, including apple seeds, sprouting potatoes, and cassava., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

An upsurge in early onset of photoaging due to repeated skin exposure to environmental stressors such as UV radiation is a challenge for pharmaceutical and cosmeceutical divisions. Current reports indicate severe side effects because of chemical or synthetic inhibitors of matrix metalloproteases (MMPs) in anti-skin aging cosmeceuticals. We evaluated the adequacy of bixin, a well-known FDA certified food additive, as a scavenger of free radicals and its inhibitory mechanism of action on MMP1, collagenase, elastase, and hyaluronidase. The anti-skin aging potential of bixin was evaluated by several biotechnological tools in silico , in vitro and in vivo . Molecular docking and simulation dynamics studies gave a virtual insight into the robust binding interaction between bixin and skin aging-related enzymes. Absorbance and fluorescence studies, enzyme inhibition assays, enzyme kinetics and in vitro bioassays of human dermal fibroblast (HDF) cells highlighted bixin's role as a potent antioxidant and inhibitor of skin aging-related enzymes. Furthermore, in vivo protocols were carried out to study the impact of bixin administration on UVA induced photoaging in C57BL/6 mice skin. Here, we uncover the UVA shielding effect of bixin and its efficacy as a novel anti-photoaging agent. Furthermore, the findings of this study provide a strong foundation to explore the pharmaceutical applications of bixin in several other biochemical pathways linked to MMP1, collagenase, elastase, and hyaluronidase.

Aggregation-induced emission (AIE) properties of an easy-to-prepare and structurally planar Schiff base derivative of the vitamin B6 cofactor pyridoxal (L) were investigated in DMSO-H2O mixed solvents. Compound L showed weak fluorescence (λem = 425 nm) in pure DMSO, but increasing the fraction of water in DMSO resulted in a significant fluorescence enhancement at 575 nm due to the restriction of intramolecular rotation (RIR) of L upon aggregation. SEM analyses revealed the formation of hairy micelle-like or needle-shaped self-assemblies/aggregates of L. The DFT calculations were performed to examine the tendency of L to form self-aggregates, and the results indicate the formation of several intramolecular non-covalent interactions that energetically favored the self-aggregation of L. The pH sensing study revealed that the red-emission of aggregates of L between pH 5.9 and 9.0 turned into green emission at the basic pH with the estimated pKa values of 9.39 and 10.22. Further, the aggregates of L were applied for the visualization of latent fingerprints (LFPs) over a non-porous glass slide.

A new dibutyl(2-oxo-2-(quinolin-8-ylamino)ethyl)phosphinate (L) was designed, synthesised and developed as a light activated optode for Th 4+ determination. The sensing performance of L was studied in solution and in the polymeric membrane phase using absorbance and emission techniques. The neutral ion carrier L exhibits weak fluorescence at 400 nm in CH 3 CN : H 2 O (9 : 1, v/v). Upon complexation of L with Th 4+ , the emission intensity at 486 nm was increased 100-fold due to chelation induced enhanced fluorescence. The L-Th 4+ binding interaction was studied using both Hill's and Job's plots. They indicate the formation of complex species in a 2 : 1 ratio with an estimated binding constant of 2.66 × 10 4 M -2 . Complex formation between L and Th 4+ was studied by NMR ( 1 H, 31 P), FTIR and LC-MS analyses. In order to synthesize a probe for the sensing of Th 4+ in 100% aqueous medium, the optode was prepared by immobilizing L as a neutral ion carrier in a PVC support using dioctyl phthalate (DOP) as a membrane solvent. The best performance of the optode was observed with a membrane composition of PVC : L : NaTPB : DOP in proportions of 35 : 5 : 3 : 57 (%, w/w) in the pH range of 4.0-8.0. The optode can detect Th 4+ concentrations down to 1.1 nM with a fast response time of 15 s and the optical response remains unaltered even after 3 months; the optode sensor can be regenerated using Na 2 EDTA solution. Finally, the optode was used for the quantification of Th 4+ in various water samples, monazite sand, and gas mantle samples.

A simple phosphoryl quinolone (L) based sensor has been synthesized for the selective recognition of Lu 3+ by spectrofluorimetric method. In methanol-water (1:1, v/v), the ligand L exhibits a weak emission peak at 400 nm upon excitation at 280 nm. Upon interaction with various f-metal and other selected metals from s, p, and d-block elements, the fluorescence of L is selectively enhanced in the presence of Lu 3+ due to the chelation enhanced fluorescence (CHEF) effects. The quantum yield (φ) of L (φ = 0.063) is enhanced to φ = 0.118 upon chelation with Lu 3+ ion. From the titration experiment, the limit of detection (LOD) of sensor L to recognize Lu 3+ is estimated down to 24.2 nM, which is much lower than the WHO guidelines (76 μM) in drinking water. The formation of host-guest complexation between L and Lu 3+ in 2:1 binding stoichiometry is studied by Job's method and the binding constant is estimated by band fit analysis (logK f  = 5.1). Further, the coordination behaviour between L and Lu 3+ is well supported by FT-IR, 1 H NMR, 13 C NMR, 31 P NMR, ESI mass spectral data and the theoretical results., (Copyright © 2019. Published by Elsevier B.V.)

In this communication, we have developed an optical chemosensor 2-amino N-(6-bromo-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)benzamide (NAPH) for selective detection of Al 3+ by reacting 4-bromo-1,8-naphthalic anhydride with 2-aminobenzohydrazide. In (DMSO:H 2 O, 1:1, v/v) medium, the selective and specific nature of NAPH towards Al 3+ was observed by the quenching along with a blue-shift in the absorption of NAPH at 465 nm that resulted in the distinct colour change from light brown to colourless. The selective complexation that occurred between NAPH and Al 3+ was investigated by 1 H NMR and DFT methods. Under similar conditions, the weakly fluorescent receptor NAPH showed a distinct fluorescence enhancement at 555 nm in the presence of Al 3+ among the other tested metal ions and anions. The NAPH·Al 3+ complex formation is reversible upon addition of strong chelating agent EDTA. The receptor NAPH can be applied to detect Al 3+ down to 2.9 μM without any interference from other tested metal ions. In addition, the receptor NAPH was successfully applied to detect Al 3+ in live HeLa cells., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This communication focusses on the synthesis of red fluorescent lysozyme cocooned gold nanoclusters (Lyso-AuNCs) that have been successfully applied for the selective and specific recognition of the vitamin B 6 cofactor pyridoxal-5'-phosphate (PLP). The red fluorescence of Lyso-AuNCs showed remarkable color change to yellow upon conjugation with PLP due to the formation of a Schiff base between the free -NH 2 present in the lysozyme and the -CHO group of PLP. The developed PLP conjugated Lyso-AuNCs (PLP_Lyso-AuNCs) was applied for the selective turn-on recognition of Zn 2+ ions in aqueous medium. The yellow fluorescence of PLP_Lyso-AuNCs exhibited significant enhancement at 475 nm in the presence of Zn 2+ producing bluish-green fluorescence attributed to the complexation-induced aggregation of nanoclusters. The nanoprobe exhibits nanomolar limit of detection for Zn 2+ ions (39.2 nM) and the practicality of the nanoprobe was validated in various environmental water samples and biological plasma, urine, and beetroot extract, with fairly good recovery percent. Also, the system was successfully implemented for the intracellular detection and monitoring of Zn 2+ in live HeLa cells. Graphical abstract Applications of red emitting lysozyme cocooned gold nanoclusters (Lyso-AuNCs) for the selective recognition of the vitamin B 6 cofactor pyridoxal-5'-phosphate (PLP) and the conjugated nano-assembly PLP_Lyso-AuNCs for turn-on detection of Zn 2+ ions in various environmental and biological samples.

One-pot approach was adopted for the synthesis of highly luminescent near-infrared (NIR)-emitting gold nanoclusters (AuNCs) using bovine serum albumin (BSA) as a protecting agent. The vitamin B 6 cofactor pyridoxal was conjugated with the luminescent BSA-AuNCs through the free amines of BSA and then employed for the nanomolar detection of Hg 2+ in aqueous medium via selective fluorescence quenching of AuNCs. This nano-assembly was successfully applied for the real sample analysis of Hg 2+ in fish, tap water and river water. The study also presents chemically-modified cellulosic paper strips with the pyridoxal conjugated BSA-AuNCs for detecting Hg 2+ ion up to 1nM., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Two new Schiff base receptors have been synthesized by condensation of pyridoxal-5-phosphate with 2-aminophenol (L(1)) or aniline (L(2)). In DMSO, the receptors showed both chromogenic and 'turn-on' fluorescence responses selectively in the presence of AcO(-) and F(-). However, in mixed DMSO-H2O medium, the receptors showed AcO(-) selective 'turn-on' fluorescence without any interference from other tested anions including F(-). The detection limit for AcO(-) was found to be 7.37 μM and 22.9 μM using the receptors L(1) and L(2), respectively., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A new study has been conducted to quantify lanthanide(III) ions using Arsenazo III-polyaminocarboxylic acid (PACA) system. The study disclosed two different analytically important information: (i) λmax of lanthanide-Arsenazo III complexes for lighter lanthanides like Ce(III) and Nd(III) did not shift from its original position on addition of PACA and (ii) for heavier lanthanides like Dy(III), Tm(III) and Lu(III) a new λmax at 538 nm was observed, while wavelengths at 610 nm and 654 nm were disappeared in presence of ethylenediaminetertracetic acid (EDTA) and trans-1,2-Diaminocyclohexane-N,N,N',N'-tetraacetic acid (DCTA), further the intensity of peak decreased with increase in lanthanide(III) ion concentration. Effect of ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and N-(2-hydroxyethyl) ethylenediamine-N,N',N'-triacetic acid (EDTA-OH) on Arsenzo(III)-Ln(III) complex is very weak and there is no analytically importance of such interaction. Moreover, this work confirms that Nd(III) and heavy lanthanides can be successfully determined with high accuracy in the working range of concentration of these metal ions., (Copyright © 2015 Elsevier B.V. All rights reserved.)