AIE based “on-off” fluorescence probe for the detection of Cu2+ ions in aqueous media

Xylan derived fluorescence carbon dots composite with cotton cellulose paper as 'turn-off' fluorescence platform for sensitive and selective detection Cu2+ in real samples

The pollution of heavy metals such as Cu2+ is still serious and the discharge of sewage of Cu2+ will cause damage to soil environment and human health. Herein, a biomass-based solid-state fluorescence detection platform (CPU-CDs) was developed as fluorescent sensor for detection Cu2+ via fluorescence and colorimetric dual-model methods in real time. CPU-CDs was composed of xylan-derived CDs (U-CDs) and cotton cellulose paper, which exhibiting good reusability, non-toxicity, excellent fluorescence characteristics and high biocompatibility. Further, CPU-CDs displayed high effectiveness and sensitivity for Cu2+ with the detection limit as low as 0.14 μM, which was well below U.S. EPA safety levels (20 μM). Practical application indicated that CPU-CDs could achieve precision response of Cu2+ change in real environment water samples with good recovery range of 90 %-119 %. This strategy demonstrated a promising biomass solid-state fluorescence sensor for Cu2+ detection for water treatment research, which is of great significance in dealing with water pollution caused by heavy metal ions.

Xylan derived carbon dots composite with PCL/PLA for construction biomass nanofiber membrane used as fluorescence sensor for detection Cu2+ in real samples

Water and soil pollution caused by Cu2+ is not conducive to sustainable development of environment and could cause damage to environment and even human body. Currently, fluorescent sensor solutions analysis method has been used for Cu2+ detection, but they also suffer from drawbacks including easy leakage, difficult storage, and inaccurate. Herein, a green solid-state biomass fluorescence platform (NBU-CDs) consisting of xylan-derived carbon dots (U-CDs) and polylactic acid/polycaprolactone (PLA/PCL) was designed by using in situ electrospinning technology. The prepared NBU-CDs fluorescence platform showed good fluorescence effect and can be served as fluorescence sensor for detecting Cu2+ with high sensitively, selectively and low detection limit (LOD = 0.83 μM). The practical applications of NBU-CDs exhibited high specificity for Cu2+ detection in zebrafish, water samples (school lake, Xuanwu Lake and Yangtze River) with high recovery rates of 97 %-104 % and soil (pond soil, grassland soil and bamboo soil) samples, respectively. The developed fluorescence platform was utilized to predict water and soil safety by monitoring Cu2+ concentration and provides a new strategy for Cu2+ detection.

A novel carbazole-based fluorometric and colorimetric sensor for the highly sensitive and specific detection of Cu2+ in aqueous solution

Based on the typical Suzuki coupling reaction and Schiff base reaction, a novel fluorescent molecular PCBW is synthesized and applied as a fluorescence and colorimetric sensor to detect Cu2+ in aqueous solution. The PCBW sensor presents the aggregation-caused quenching (ACQ) effect and at 1 × 10-5 mol L-1 it emits the strongest turquoise fluorescence in the DMSO-H2O system (fw = 40%). The sensor exhibits a 'turn-off' fluorescent characteristic by adding Cu2+, and its fluorescent intensity shows a reliable linear relationship with the Cu2+ concentration in the range of 0-6 × 10-6 mol L-1, with a detection limit of 1.19 × 10-8 mol L-1. Meanwhile, the PCBW sensor also exhibits the colorimetric sensing from colorless to light yellow. The sensor has good selectivity and anti-interference and its pH application range can be extended from 5 to 10. The intramolecular charge transfer (ICT) is speculated as the main fluorescence mechanism of PCBW. In addition, the sensor presents good reusability and is practicable to detect Cu2+ in diverse aqueous samples.

Colorimetric Cu2+ Detection of (1E,2E)-1,2-Bis((1H-pyrrol-2-yl)methylene)hydrazine Using a Custom-Built Colorimeter

The compound (1E,2E)-1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine (1) was investigated for its chemosensor application. The colorimetric response of 1 with various ions was investigated, and the selective optical change upon mixing with Cu²⁺ was found. The Cu²⁺ binding stoichiometry of 1 derived from Job's plot and the in silico study give us the tentative structural detail of the binding mode of 1 and Cu²⁺ being 1:1. The binding constant between 1 and Cu²⁺ from the Benesi-Hildebrand plot was 1.49 × 10⁴ M^-1. The limit of detection of 1 in Cu²⁺ detection was 0.64 μM (0.040 ppm), which is much lower than the WHO and US EPA maximum allowable Cu²⁺ level in drinking water (2 and 1.3 ppm, respectively). The custom-built colorimeter demonstrates a good linear relationship between Cu²⁺ concentration and electrical resistance (Ω) upon 1-Cu²⁺ ion binding.

2,4-Diamino-5-(5-amino-3-oxo-2,3-dihydro-1H-pyrazol-4-yl)-5H-chromeno[2,3-b]pyridine-3-carbonitrile

The one-pot synthesis methodology has become the leading atom-economical approach for various chemical transformations in a single pot, without purifying intermediate compounds. Chromeno[2,3-b]pyridines are an important class of heterocyclic compounds with versatile biological profiles and other different applications The 5-aminopyrazole system represents a significant heterocyclic template that has gained considerable interest because of its long history of use in the pharmaceutical and agrochemical industries. In this communication, the one-pot transformation of salicylaldehyde, malononitrile dimer, and 2-cyanoacetohydrazide in an ethanol/pyridine mixture was investigated to provide 2,4-diamino-5-(5-amino-3-oxo-2,3-dihydro-1H-pyrazol-4-yl)-5H-chromeno[2,3-b]pyridine-3-carbonitrile in good yield. The structure of the novel compound was confirmed by means of elemental analysis, mass-, nuclear magnetic resonance, and infrared spectroscopy.

New Genetic Bomb Trigger: Design, Synthesis, Molecular Dynamics Simulation, and Biological Evaluation of Novel BIBR1532-Related Analogs Targeting Telomerase against Non-Small Cell Lung Cancer

Telomeres serve a critical function in cell replication and proliferation at every stage of the cell cycle. Telomerase is a ribonucleoprotein, responsible for maintaining the telomere length and chromosomal integrity of frequently dividing cells. Although it is silenced in most human somatic cells, telomere restoration occurs in cancer cells because of telomerase activation or alternative telomere lengthening. The telomerase enzyme is a universal anticancer target that is expressed in 85–95% of cancers. BIBR1532 is a selective non-nucleoside potent telomerase inhibitor that acts by direct noncompetitive inhibition. Relying on its structural features, three different series were designed, and 30 novel compounds were synthesized and biologically evaluated as telomerase inhibitors using a telomeric repeat amplification protocol (TRAP) assay. Target compounds 29a, 36b, and 39b reported the greatest inhibitory effect on telomerase enzyme with IC₅₀ values of 1.7, 0.3, and 2.0 μM, respectively, while BIBR1532 displayed IC₅₀ = 0.2 μM. Compounds 29a, 36b, and 39b were subsequently tested using a living-cell TRAP assay and were able to penetrate the cell membrane and inhibit telomerase inside living cancer cells. Compound 36b was tested for cytotoxicity against 60 cancer cell lines using the NCI (USA) procedure, and the % growth was minimally impacted, indicating telomerase enzyme selectivity. To investigate the interaction of compound 36b with the telomerase allosteric binding site, molecular docking and molecular dynamics simulations were used.

Highly Sensitive 'on-off' Pyrene Based AIEgen for Selective Sensing of Copper (II) Ions in Aqueous Media

A Fluorescent chemosensor based on pyrene scaffold, 5-diethylamino-2-(pyren-1-yliminomethyl)-phenol (PDS) is synthesized using condensation method. It displays novel aggregation-induced emission (AIE) phenomena in its aggregated/solid state. The AIE characteristic of PDS is studied in CH₃CN/H₂O mixtures at different volume percentage of water and morphology of the aggregated particles are investigated by DLS and optical fluorescence microscopic study. The probe is aggregated into ordered one-dimensional (1-D) rod like microcrystals and exhibit high efficiency of solid-state emission with green colour. By taking advantage of its interesting AIE feature, the aggregated hydrosol has been utilized as 'off-on' type fluorescence switching chemosensor with superb selectivity and sensitivity towards Cu²⁺ions and the limit of detection (LOD) was calculated as low as 6.3 µM. A high Stern-Volmer quenching constant was estimated to be 2.88 × 10⁵ M^-1. The proposed chemosensor with AIE feature reveals a prospective view for the on-site visual recognition of Cu²⁺ ions in fluorescent paper strips and the synthesized probe is also exploited to find out the concentration of Cu²⁺ions in real water samples.

Tetraphenylethylene AIEgen bearing thiophenylbipyridine receptor for selective detection of copper(ii) ion

A new tetraphenylethylene (TPE) AIEgen appended with a thiophenylbipyridine moiety exhibits sensitivity and selectivity towards copper ions via a PET “turn on–turn off” mechanism.

A novel supramolecular polymer gel-based long-alkyl-chain-functionalized coumarin acylhydrazone for the sequential detection and separation of toxic ions

A novel approach for the detection and separation of toxic ions was successfully developed via the introduction of competitive reactions into a long-alkyl-chained acylhydrazone-based coumarin supramolecular polymer, chemosensor OGC (3%, n-BuOH/H₂O), which showed sequential detection and separation of CN^-, Fe³⁺ and S^2-, Ag⁺ in the gel state with high selectivity and sensitivity. Moreover, the ion-responsive films were prepared for the convenient and continuous detection of CN^-, Fe³⁺ and S^2-, Ag⁺ in water solution.

A novel AIE chemosensor based on a coumarin functionalized pillar[5]arene for multi-analyte detection and application in logic gates

A novel coumarin functionalized pillar[5]arene (PX) with AIE fluorescence could sequentially detect multiple analytes in aqueous medium with high sensitivity.