Vanillin-coumarin hybrid molecule as an efficient fluorescent probe for trace level determination of Hg(II) and its application in cell imaging

Wool Fabric with an Improved Durable Biological Resistance Using a Coumarin Derivative

Wool is the most widely used proteinic natural fiber in the clothing industry by virtue of its versatile properties. Unfortunately, wool, as a natural fiber, is more susceptible to attack by microorganisms and moths, which may cause harm to the fiber and human health. That is why the antimicrobial and mothproof finishing of natural textiles is of prime importance to the textile and clothing industry. Herein, wool fabric was treated with the synthesized 6-aminocoumarin adopting the pad-dry-cure technique with or without a cross-linker. The treated wool fabric was evaluated for its antimicrobial activity against Staphylococcus aureus and Escherichia coli. The treated wool fabric was also tested for moth-proofing performance against Tineola Bisselliella through assessing the fabric weight loss. Various analyses were conducted to assign the alteration in the structure of the treated wool fibers, viz., urea-bisulfite solubility, carboxylic content, Fourier transform infrared spectroscopy, and X-ray diffraction pattern (XRD). Scanning electron microscopy displayed the surface of wool fabric before and after treatment. Some physical and mechanical properties were also assessed. Results revealed that treated wool fabric showed a bacterial resistance to Gram +ve and Gram -ve bacteria, in addition to its improved resistance to moth larvae attack without deterioration in the fabric's inherent properties.

Fluorescence Variation in Selective Sensing of Hg2+and Cu2+ Ions By Coumarin-xanthene Fused Optical Probe

The fluorescent moieties coumarin and xanthene (R6GCP) combined in a single molecule was designed and synthesized. The colorimetric and fluorescent variation of the probe towards the copper and mercury ions sensing is examined. With the added copper/mercury ions to the solution of R6GCP in DMF:H2O (2:8, v/v), the probe showed deep red color from yellow color. The probe showed turn-off and turn-on fluorescence for copper and mercury ion respectively. In the presence of other competing metal ions, the probe showed better sensitivity towards copper and mercury ions. The probe's detection limit found to be 5.29 × 10^-6 M and 1.24 × 10^-5 M for Cu²⁺ and Hg²⁺ ion respectively by the UV-visible spectral measurement. Fluorescence measurement, the detection limit for the Cu²⁺ and Hg²⁺ ions detection by this probe is 1.91 × 10^-7 M, and 1.32 × 10^-8 M respectively. 1:1 binding stoichiometry was confirmed between the probe and Cu²⁺/Hg²⁺ ions from jobs plot by UV-visible spectral technique. Moreover, R6GCP combined filter paper were prepared. These test paper containing probe could detect Cu²⁺/Hg²⁺ ions in real-time with a spontaneous color change.

Organic Molecules Containing N, S and O Heteroatoms as Sensors for the Detection of Hg(II) Ion; Coordination and Efficiency toward Detection

Rapid detection of potentially toxic heavy metals like Hg(II) has attracted great attention in the last few decades due to the importance to maintain a safe and sustainable environment for human beings. Coordination chemistry and concepts therein, play an important role in the detection of Hg(II). Size, charge, and nature of the donor atom and the respective cation (metal ion), are crucial in selective interactions between the sensor and metal ions. The sensors designed for the purpose, coordinate to Hg(II) ion through various donor sites, coordination causes a change in the electron density in organic molecules and results in either visible color change or enhancing/quenching fluorescence intensity. Since Hg(II) is soft metal, with d10 electron system, so majority of the sensors have soft donor sites which prefer to coordinate with Hg(II). Oxygen is also present in some chelating ligands which is least preferred coordination site, due to its hard nature. There are several reports of replacing other ligating sites by sulfur for enhanced mercury sensing. In some cases, desulfurization is being detected as clear change in spectral behavior during the sensing process. Efforts are still in progress to design and introduce a sensor with utmost sensitivity and selectivity. In this review, we made an attempt to explain the coordination aspects of Hg(II) detectors, reasons for poor efficiency and possible suggestions to improve the selection criterion of various compounds. It will help researchers to know about important concepts in designing more sensitive and selective sensors for detection of Hg(II) in environmental and biological samples.

Thymine-Functionalized Gold Nanoparticles (Au NPs) for a Highly Sensitive Fiber-Optic Surface Plasmon Resonance Mercury Ion Nanosensor

Mercury ion (Hg²⁺) is considered to be one of the most toxic heavy metal ions. Once the content of Hg²⁺ exceeds the quality standard in drinking water, the living environment and health of human beings will be threatened and destroyed. Therefore, the establishment of simple and efficient methods for Hg²⁺ ion detection has important practical significance. In this paper, we present a highly sensitive and selective fiber-optic surface plasmon resonance (SPR) Hg²⁺ ion chemical nanosensor by designing thymine (T)-modified gold nanoparticles (Au NPs/T) as the signal amplification tags. Thymine-1-acetic acid (T-COOH) was covalently coupled to the surface of 2-aminoethanethiol (AET)-modified Au NPs and Au film by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-Hydroxysuccinimide (EDC/NHS) activation effect, respectively. In the presence of Hg²⁺ ions, the immobilized thymine combines specifically with Hg²⁺ ions, and forms an Au/thymine-Hg²⁺-thymine/Au (Au/T-Hg²⁺-T/Au) complex structure, leading to a shift in SPR wavelength due to the strong electromagnetic couple between Au NPs and Au film. Under optimal conditions, the proposed sensor was found to be highly sensitive to Hg²⁺ in the range of 80 nM–20 µM and the limit of detection (LOD) for Hg²⁺ was as low as 9.98 nM. This fiber-optic SPR sensor afforded excellent selectivity for Hg²⁺ ions against other heavy metal ions such as Fe³⁺, Cu²⁺, Ni²⁺, Ba²⁺, K⁺, Na⁺, Pb²⁺, Co²⁺, and Zn²⁺. In addition, the proposed sensor was successfully applied to Hg²⁺ assay in real environmental samples with excellent recovery. Accordingly, considering its simple advantages, this novel strategy provides a potential platform for on-site determination of Hg²⁺ ions by SPR sensor.

Phytochemicals toward Green (Bio)sensing

Because of numerous inherent and unique characteristics of phytochemicals as bioactive compounds derived from plants, they have been widely used as one of the most interesting nature-based compounds in a myriad of fields. Moreover, a wide variety of phytochemicals offer a plethora of fascinating optical and electrochemical features that pave the way toward their development as optical and electrochemical (bio)sensors for clinical/health diagnostics, environmental monitoring, food quality control, and bioimaging. In the current review, we highlight how phytochemicals have been tailored and used for a wide variety of optical and electrochemical (bio)sensing and bioimaging applications, after classifying and introducing them according to their chemical structures. Finally, the current challenges and future directions/perspective on the optical and electrochemical (bio)sensing applications of phytochemicals are discussed with the goal of further expanding their potential applications in (bio)sensing technology. Regarding the advantageous features of phytochemicals as highly promising and potential biomaterials, we envisage that many of the existing chemical-based (bio)sensors will be replaced by phytochemical-based ones in the near future.

Crystal structure of 3-methyl-2-oxo-2H-chromen-7-yl propionate, C13H12O4

C13H12O4, triclinic, P1̄ (no. 2), a = 6.141(5) Å, b = 8.108(6) Å, c = 12.234(9) Å, α = 79.257(12)°, β = 76.820(12)°, γ = 74.687(11)°, V = 566.8(7) Å3, Z = 2, R gt(F) = 0.0515, wR ref(F 2) = 0.1575, T = 296(2) K.

A novel dithiourea-appended naphthalimide "on-off" fluorescent probe for detecting Hg2+ and Ag+ and its application in cell imaging

An effective dithiourea-appended 1,8-naphthalimide fluorescent probe was designed and synthesized. This probe could recognize Hg²⁺ and Ag⁺ sensitively and selectively in neutral and alkaline conditions. Moreover, the probe detected Hg²⁺ alone at pH between 2 and 6. The sensing ability of the probe was explored by UV-vis, fluorescence, FTIR and ¹H NMR spectroscopy. The probe was quenched by Hg²⁺ and Ag⁺ with 1:1 binding ratios in MeCN/H₂O (4/1, v/v) mixed solution with binding constants of 3.76 × 10⁴ L mol^-1 and 2.47 × 10⁴ L mol^-1, respectively. The linear concentration ranges for Hg²⁺ and Ag⁺ were 0-17 μmol L^-1 and 0-24 μmol L^-1 with detection limits of 0.83 μmol L^-1 and 1.20 μmol L^-1, respectively, which allowed for the quantitative determination of Hg²⁺ and Ag⁺. The new probe, 3a, was successfully applied to the fluorescence imaging of Hg²⁺ and Ag⁺ in HepG2 cells, demonstrating its potential application in biological science. Moreover, 3a was used to measure Hg²⁺ and Ag⁺ in tap water, drinking water and ultrapure water samples. The recoveries of Hg²⁺ and Ag⁺ in water samples were 96-99% and 98-103%, respectively. Therefore, the proposed method showed promising perspectives for its application, aimed at detecting Hg²⁺ and Ag⁺ in fluorescence imaging and real water samples.

Rhodamine 6G hydrazone with coumarin unit: a novel single-molecule multianalyte (Cu2+ and Hg2+) sensor at different pH value

An effective colourimetric and ratiometric fluorescent probe for Cu²⁺ in neutral aqueous media was synthesised. Moreover, the probe could sense Hg²⁺ with fluorescence enhancement at high pH.

Preparation of neutral red functionalized Fe3O4@SiO2 and its application to the magnetic solid phase extraction of trace Hg(ii) from environmental water samples

Trace level of Hg(ii) was extracted from water by neutral red functionalized Fe₃O₄@SiO₂ based on the electrostatic and coordinate interactions of Hg(ii) with neutral red.

Synthesis of silica gel supported salicylaldehyde modified PAMAM dendrimers for the effective removal of Hg(II) from aqueous solution

A series of silica gel supported salicylaldehyde modified PAMAM dendrimers (SiO2-G0-SA ∼ SiO2-G2.0-SA) were synthesized and their structures were characterized by FTIR, XRD, SEM, TGA, and porous structure analysis. The feasibility of these adsorbents for the removal of Hg(II) from aqueous solution was first described and the adsorption mechanism was proposed. The adsorption was found to depend on solution pH, the generation number of salicylaldehyde modified PAMAM dendrimers, contact time, temperature, and initial concentration. Results showed that the optimal pH was about 6 and the adsorption capacity increased with the increasing of generation number. Density functional theory (DFT) method was used to investigate the coordination geometries and the chelating mechanism. Adsorption kinetics was found to follow the pseudo-second-order model with film diffusion process as rate controlling step. Adsorption isotherms revealed that adsorption capacities increased with the increasing of temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were employed to analyze the equilibrium data. The adsorption can be well described by Langmuir isotherm model and took place by chemical mechanism. The thermodynamics properties indicated the adsorption processes were spontaneous and endothermic nature. The maximum adsorption capacity of SiO2-G0-SA, SiO2-G1.0-SA, and SiO2-G2.0-SA were 0.91, 1.52, and 1.81 mmol g(-1), respectively. The considerable higher adsorption capacity compared with other adsorbents indicates SiO2-G0-SA ∼ SiO2-G2.0-SA are favorable and useful for the uptake of Hg (II), and can be potentially used as promising adsorbents for the effective removal of Hg(II) from aqueous solution.

Selective sensing of Hg²⁺ using rhodamine-thiophene conjugate: red light emission and visual detection of intracellular Hg²⁺ at nanomolar level

Rhodamine-thiophene conjugate (L) has been synthesized and characterized by (1)H NMR, FTIR and mass spectra. L shows a large enhancement in emission intensity in presence of Hg(2+). Moreover, naked eye color of L becomes intense red in presence of Hg(2+). The lowest detection limit for Hg(2+) is 1 × 10(-9)M in HEPES buffer (0.1M in EtOH/water, 1/1, v/v, pH 7.4). Hg(2+) induced chelation enhanced fluorescence (CHEF) is associated with spirolacram ring opening of the rhodamine unit. Trace level intracellular Hg(2+) is visualized under fluorescence microscope.

A new 1,8-naphthalimide-based colorimetric and "turn-on" fluorescent Hg2+ sensor

A new fluorescent molecule 4-(bis(2-(ethylthio)ethyl)amino)-N-n-butyl-1,8-naphthalimide (BTABN) was reported. Its UV-vis absorption and fluorescence spectra were almost not dependent on the pH, but remarkably and selectively affected by Hg(2+). Upon the addition of Hg(2+) in EtOH/H(2)O (1/2,v/v), the absorption wavelength maxima were blueshifted from 436 nm to 376 nm with a naked-eye observed color change, and the fluorescence was greatly enhanced with a 14 nm blueshift within 1 min. Na(+), K(+), Ca(2+), Mg(2+), Cu(2+), Zn(2+), Cr(3+), Pb(2+), Ni(2+), Fe(2+), Mn(2+), Co(2+), Cd(2+) showed no obvious interferences with the detection. The binding stoichiometry indicates that a 1:1 complex is formed between Hg(2+) and BTABN. The response of the UV-vis absorption and the fluorescence spectra to Hg(2+) can be attributed to the joint contribution of the PET and ICT process.