A turn-on fluorescent probe for Lu3+ recognition and bio-imaging in live cells and zebrafish

Application of Novel Gill Cell Line from Lates calcarifer for Recognizing Metals Using Probes

Lates calcarifer (Bloch) is a potential candidate fish species for culture in marine and brackishwater. A continuous gill cell line was derived from L. calcarifer by the explant culture method and has been passaged for 132 times, in Leibovitz's L-15 medium containing 10% fetal bovine serum (FBS) at 28 °C. The cells showed a rate of recovery between 90 and 95% after being successfully cryopreserved at various passage levels and formed monolayer in 2-3 days without any morphological changes. Immunophenotypic analysis of the SBG cell line revealed that they are of epithelial origin. Polymerase chain reaction assay using mitochondrial 12S rRNA primer specific to L. calcarifer was used to confirm the authenticity of the established gill cell line origin from seabass. The transfection efficiency was evaluated in Seabass Gill (SBG) cell line using pEGFP-N1 and Lipofectamine™ 3000. Transfection efficiency was found to be between 13 and 16%. The cytotoxicity of three different metal detecting probes was evaluated by MTT and Alamar blue assays to determine safe concentration. The result revealed that SBG cell line can be applied for recognition of metals using probes. The current study established, for the first time, a gill-derived cell line (SBG) from Lates calcarifer and its application for the detection of intracellular indium, mercury, and lutetium ions by specific fluorescent probes.

Chromene-chromene Schiff base as a fluorescent chemosensor for Th4+ and its application in bioimaging of Caenorhabditis elegans

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 Th4+ ions. This report investigated COM-CH's sensing ability towards Th4+ chromogenic and fluorogenic methods in ACN: H2O (8:2, v/v) with Th4+ ions. The COM-CH-Th4+ 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 Th4+ was investigated using NMR, FTIR spectrometry, and density functional theory calculations. The COM-CH and Th4+ are bound with 2:1 stoichiometry and an association constant of 1.92 × 108 M-2. The probe's performance enabled the analysis of monazite sand and water samples for Th4+ content. The probe successfully detected Th4+ content in Caenorhabditis elegans, marking the first Th4+ detection in animal models.

Chromene Carbohydrazide- Schiff Base as a Highly Selective Turn-Off Fluorescence Chemosensor for In3+ Ion and its Application

A new 7-(diethylamino)-2-oxo-2 H-chromene-3-carbohydrazide design to synthesize a simple Schiff-base condition. The synthesized molecules' (probe L) photophysical properties were investigated in various solvent systems and solvent-poor-solvent assays. Probe L exhibits the absorbance band at 440 nm and the emission band at 488 nm in DMSO: H2O (7:3, v/v). Further, probe L shows selective turn-off emission recognition of In3+ ions in DMSO: H2O (7:3, pH = 7.4). By Job's plot and ESI mass analysis, probe L forms a 1:2 stoichiometry complex with an estimated association constant of 4.04 × 104 M- 2 with In3+ ions. Metal induces CHEQ (chelation-caused fluorescence quenching) to reduce the intensity of probe L's emission, and the estimated quenching constant was 4.52 × 104 M- 1. The limit of detection was found to be 5.93 nM; the time response of the sensor is instantaneous, and its reversible nature was confirmed using EDTA additions. Solid substrates (test strips) were designed and tested for fast, reliable, user-friendly, and real-time sensing of In3+ ions for on-site applications. The binding mechanism of probe L with In3+ ions was investigated using 1H NMR titration and DFT/TD-DFT studies.

Real time sensor for Fe3+, Al3+, Cu2+ & PPi through quadruple mechanistic pathways using a novel dipodal quinoline-based molecular probe

A quinoline-based small molecular probe, H₂L was designed, synthesized and characterized by different spectroscopic methods. It was utilized as a multi-responsive probe for the detection of Fe³⁺, Al³⁺, Cu²⁺ and PPi. It showed very selective instant turn-on fluorimetric response towards Fe³⁺and Al³⁺ with a detection limit in nanomolar range. Solutions of H₂L containing Fe³⁺ or Al³⁺ could sequentially sense PPi by a turn-off mechanism. Also, H₂L could determine the presence of Cu²⁺ very selectively among a series of other metal ions by a sharp change in colour. Detection of Cu²⁺ through colorimetry was further investigated by systematic UV-Vis studies and the potential of H₂L to act as a potential colorimetric sensor for Cu²⁺ was suitably established. Filter-paper strip experiments were conducted to demonstrate the practical utility of the proposed sensor. Potential applications of H₂L as a sensor for pH in the acidic range has also been explored.