Simple Colorimetric and Fluorescence Chemosensing Probe for Selective Detection of Sn2+ Ions in an Aqueous Solution: Evaluation of the Novel Sensing Mechanism and Its Bioimaging Applications.

An easily accessible colorimetric and fluorescence probe 4-((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)benzenesulfonamide (4CBS) was successfully developed for the selective and sensitive detection of Sn2+ in an aqueous solution. The sensing mechanism involves reduction of -C═O into -C-OH groups in 4CBS upon the addition of Sn2+, which initiates the fluorescence turn-on mode. A better linear relationship was achieved between fluorescence intensity and Sn2+ concentration in the range of 0-62.5 µM, with a detection limit (LOD) of 0.115 µM. The binding mechanism of 4CBS for Sn2+ was confirmed by Fourier transform infrared analysis, NMR titrations, and mass (electrospray ionization) spectral analysis. Likewise, the proposed sensing mechanism was supported by quantum chemical calculations. Moreover, bioimaging studies demonstrated that the chemosensing probe 4CBS is an effective fluorescent marker for the detection of Sn2+ in living cells and zebrafish. Significantly, 4CBS was able to discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.

Simple and selective optical biosensor using Ultrasonicator synthesis of 5-((anthracen-9-ylmethylene) amino)-2,3-dihydrophthalazine-1,4-dione for direct detection of ascorbic acid in vegetables and fruits.

We report an optical biosensor using imine, 5-((anthrcene-9-ylmethylene) amino)-2,3dihydrophthalazine) 1-4-dione (ADD) for direct detection of ascorbic acid (AA) via FRET quenched. The ADD was successfully prepared by using simple ultra - sonication method, which was characterized by various spectroscopic techniques. The fluorescence intensity of ADD probe was drastically quenched in presence of AA, and shown excellent selectivity towards the detection of AA in presence of possible biological active interferences. A wide linear range from 0.25 to 190 µM was achieved towards the detection of AA with a LOD of 10 nM. The occurrence of FRET mechanism is due to intermolecular hydrogen bonding between ADD and AA, which was confirmed by Density Functional Theory calculations. Moreover, the biosensor was successfully applied for the detection of AA in real samples such as fruits and vegetables to demonstrate the practicability. In addition, the developed biosensor could be a simple and economically cheap platform for the detection of AA in food samples.

Simple Fluorescence Turn-On Chemosensor for Selective Detection of Ba2+ Ion and Its Live Cell Imaging.

A phenoxazine-based fluorescence chemosensor 4PB [(4-(tert-butyl)-N-(4-((4-((5-oxo-5H-benzo[a]phenoxazin-6-yl)amino)phenyl)sulfonyl)phenyl)benzamide)] was designed and synthesized by a simple synthetic methods. The 4PB fluorescence chemosensor selectively detects Ba2+ in the existence of other alkaline metal ions. In addition, 4PB showed high selectivity and sensitivity for Ba2+ detection. The detection limit of 4PB was 0.282 µM and the binding constant was 1.0 × 106 M-1 in CH3CN/H2O (97.5:2.5 v/v, HEPES = 1.25 mM, pH 7.3) medium. This chemosensor functioned through the intramolecular charge transfer (ICT) mechanism, which was further confirmed by DFT studies. Live cell imaging in MCF-7 cells confirmed the cell permeability of 4PB and its capability for specific detection of Ba2+ in living cells.

Sonochemically recovered silver oxide nanoparticles from the wastewater of photo film processing units as an electrode material for supercapacitor and sensing of 2, 4, 6-trichlorophenol in agricultural soil samples.

The present work describes the sensing application and supercapacitive behavior of silver oxide nanoparticles recovered from wastewater of photo film processing units via one-pot green sonochemical recovery process. The recovered silver oxide nanoparticles (Ag2O NPs) were characterized by spectral techniques such as FT-IR, Raman, UV-Vis and analytical tools such as XRD, FE-SEM, TEM, EDX, XPS and BET. In view of Ag2O NPs as electrode material with wide technological applications, the recovered Ag2O NPs were examined for their sensing and supercapacitive behavior. The developed sensor was explored to detect 2, 4, 6-trichlorophenol, and as expected it shows moral parameters which are required of an effective sensor. Therefore, it was exploited for the quantification of 2, 4, 6-trichlorophenol in soil samples from the agricultural area. Cyclic voltammetric (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopic (EIS) studies on the recovered Ag2O NPs coated Ni foam electrode depicted the pronounced capacitive behavior. The GCD studies revealed an enhanced electrochemical performance, particularly with the large specific capacitance of 530 F/g at a current density of 1 A/g. The cyclic stability of the electrode material was identified with 88% retention in specific capacitance even after 5000 GCD cycles. These results strongly proved that the recovered Ag2O NPs are potential candidates for sensing and supercapacitor applications.

Synthesis, Characterization and Solvatochromic Studies Using the Solvent Polarity Parameter, ENT on 2-Chloro-3-Ethylamino-1,4-Naphthoquinone.

Quinones are molecules with varied biological activities and electronic properties which are used for important applications [1, 2]. Quinone with a heteroatom substituted, namely 2-chloro-3-ethylamino-1,4-naphthoquinone (N-CAN) was synthesized and characterized by various techniques such as H1-NMR, C13-NMR, Mass spectroscopy and FT-IR spectroscopy. In this study, the solvatochromic effects on the spectral properties of 2-chloro-3-ethylamino-1,4-naphthoquinone have been investigated in different solvents taking into consideration, the solvent parameters like dielectric constant (ε) and refractive index (η) of different solvent polarities. Using Lippert-Mataga, Bakshiev's, Kawski-Chamma-Viallet and Reichardt equations, the ground state (µg) and excited state (µe) dipole moments were calculated. The angle between the excited state and ground state dipole moments were also calculated. Graphical Abstract ᅟ.