A fluorescent chemosensor for relay recognition of Fe 3+ and PO 4 3− in aqueous solution and its applications

An abiotic carbon dots@ ZIF-90 fluorescent probe for rapid and reliable detection of adenosine triphosphate

ATP is a high-energy compound that plays a vital role in biological metabolism. Abnormal changes in ATP concentration are related to various diseases and reflect microbial metabolism in biofilms. In this work, we prepared carbon quantum dots (CDs) with aggregation-induced fluorescence inhibition effect using the bacterial culture medium as raw material with a hydrothermal method. Then, an abiotic fluorescent nanoprobe named CDs@zeolitic imidazolate frameworks-90 (ZIF-90) was facilely synthesized by encapsulating CDs into ZIF-90. Owing to the encapsulation of CDs in the hollow structure of ZIF-90, the blue fluorescence emission of CDs@ZIF-90 decreased significantly. In the presence of ATP, the ZIF-90 framework was destroyed due to the strong coordination between ATP and Zn²⁺. The released CDs exhibited stronger fluorescence intensity, which was closely related to the ATP concentration. The convenient synthesis process and rapid ATP-responsive ability make CDs@ZIF-90 highly promising for clinical and environmental analysis.

A facile COF loaded-molybdate resonance Rayleigh scattering and fluorescence dimode probe for determination of trace PO43

A new covalent organic framework loaded-molybdate (COF_Mo) nanomaterial was prepared simply by solvothermal procedure and characterized by electron microscopy and molecular spectral techniques. The COF_Mo had a strong resonance Rayleigh scattering (RRS) signal at 465 nm and a fluorescence peak at 345 nm. When the PO₄^3- was added in the system, it reacted with the molybdate, which loaded on the surface of COF particles, to form stable phosphomolybdic acid occurring RRS/fluorescence-energy transfer, the RRS and fluorescence signals were decreased. The decreased RRS/fluorescence intensities were linear to the PO₄^3- concentration in the range of 0.053-3.2 nmol/L and 0.10-3.2 nmol/L, with a detection limit of 0.050 nmol/L and 0.090 nmol/L respectively. Accordingly, a new and facile RRS/fluorescence dimode method for detection of trace PO₄^3- was established, only one fluorometer was used.

Design, synthesis and biological evaluation of dihydrofurocoumarin derivatives as potent neuraminidase inhibitors

Neuraminidase (NA) is a promising target for development of anti-influenza drugs. In this study a dihydrofurocoumarin derivative ZINC05577497 was discovered as a lead NA inhibitor based on docking-based virtual screening technique. The optimization of lead ZINC05577497 led to the discovery of a series of novel NA inhibitors 5a-5j. Compound 5b has the most potent activity against NA with IC₅₀ = 0.02 µM, which is lower than those of the reference oseltamivir carboxylate (OSC) (IC₅₀ = 0.04 µM) and ZINC05577497 (IC₅₀ = 0.11 µM). Other target compounds also show potential inhibition of NA activity. Molecular docking results indicate that the good potency of 5b may be attributed to the elongation of the dihydrofurocoumarin ring to the 150-cavity. The results of this paper will be useful to discover more potent NA inhibitors.

Fabrication of multi-functional carbon dots based on "one stone, three birds" strategy and their applications for the dual-mode Fe3+ detection, effective promotion on cell proliferation and treatment on ferric toxicosis in vitro

The ingenious design of multi-functional materials to simultaneously achieve the accurate detection of targets and effective treatment of target-related diseases is of great significance for both practical and clinical applications. Accordingly, based on their advantages of facile synthesis and function designability, functional nanomaterials have become promising candidates for integrating multi-functionality into one platform, especially carbon dot (CD)-based materials. Herein, deferoxamine (DFO)-inspired CDs with integrated "sense and treatment" potential were elaborately designed and fabricated via a one-pot hydrothermal synthesis by employing l-aspartic acid (Asp) and 2,5-diaminobenzenesulfonic acid (DABSA) as the reactants. A series of characterization results distinctly confirmed that the synthesized CDs possessed a unique chemical composition, uniform spherical morphology (diameter of around 5 nm) and good dispersibility in aqueous solution, exhibiting excellent fluorescence stability under different conditions. Owing to the complexation interaction between Fe3+ and the functional groups of CDs, the selective and sensitive detection of Fe3+ could be successfully realized through fluorescent and colorimetric dual-mode detection based on the statistic quenching in the initial stage, and subsequently the FRET process. Furthermore, these CDs could be utilized for cellular imaging and effective Fe3+ detection due to their outstanding biocompatibility and cytoplasmatic distribution. More significantly, these DFO-inspired CDs could remarkably promote the proliferation of various mammalian cells. Particularly, the results in this work obviously indicated that this type of CDs could weaken the damage of Fe3+ towards the physiological behaviors of cells, helping the cells to regain their capability of differentiation after ferric toxicosis. Therefore, this work presents an original approach for the design and fabrication of multi-functional materials according to the "one stone, three birds" strategy, which may be an optional solution to develop various multi-functional platforms for disease diagnosis and corresponding clinical treatment.

Discovery of a novel camphor-based fluorescent probe for Co2+ in fresh vegetables with high selectivity and sensitivity

Cobalt is an essential micronutrient for human beings. The excessive intake of cobalt may lead to heart-related diseases. In this work, a novel fluorescent probe 1,1'-(((6,11,11-trimethyl-6,7,8,9-tetrahydro-6,9-methanopyridazino[4,5-b]quinoxaline-1,4-diyl)bis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol) (PDS) was synthesized from camphor. The probe PDS could be utilized to selectively recognize Co²⁺ over other metal ions. There is a good linear relationship between fluorescence intensity of PDS and Co²⁺ concentration within 0-20 μM, and its detection limt was found to be 0.925 μM, which is far lower than the national standard for cobalt in drinking water in China. The possible coordination mechanism of PDS with Co²⁺ was determined by nuclear magnetic resonance (NMR), high resolution mass spectrometry (HRMS) and density functional theory (DFT). The probe PDS was also successfully applied in detection of Co²⁺ in tap water and fresh vegetables.

Developed a novel quinazolinone based turn-on fluorescence probe for highly selective monitoring hypochlorite and its bioimaging applications

A novel quinazolinone based turn-on fluorescence probe for sensitive monitoring hypochlorite was prepared using the mild condensation reaction between 2-(2'-hydroxyphenyl)-4(3H)-quinazolinone derivative and 4-methylbenzenesulfonyl hydrazide. The probe exhibited specific selectivity to ClO^- with obvious optical signal changes from weak fluorescence at 560 nm to a strong fluorescence emission at 520 nm and color changes from colorless to yellow, which could be noticed by the naked eye. The detection limit toward hypochlorite is as low as 11.4 nM. Moreover, the probe could sensitively response to ClO^- in living cells with satisfying imaging effect and has been successfully applied to the determination of ClO^- in practical water samples, which indicated that the probe has certain application potential for hypochlorite monitoring.

A turn-on Schiff base fluorescent probe for the exogenous and endogenous Fe3+ ion sensing and bioimaging of living cells

A Schiff base fluorescent probe, namely naphthalic anhydride – (2-pyridine) hydrazone (NAH), has been synthesized and developed for the highly selective and sensitive monitoring of Fe³⁺ ions in an aqueous solution and living cells.

Coumarin-Based Small-Molecule Fluorescent Chemosensors

Coumarins are a very large family of compounds containing the unique 2H-chromen-2-one motif, as it is known according to IUPAC nomenclature. Coumarin derivatives are widely found in nature, especially in plants and are constituents of several essential oils. Up to now, thousands of coumarin derivatives have been isolated from nature or produced by chemists. More recently, the coumarin platform has been widely adopted in the design of small-molecule fluorescent chemosensors because of its excellent biocompatibility, strong and stable fluorescence emission, and good structural flexibility. This scaffold has found wide applications in the development of fluorescent chemosensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, as well as in the biology and medical science communities. This review focuses on the important progress of coumarin-based small-molecule fluorescent chemosensors during the period of 2012-2018. This comprehensive and critical review may facilitate the development of more powerful fluorescent chemosensors for broad and exciting applications in the future.

A new “ON–OFF–ON” fluorescent probe for sequential detection of Fe3+ and PPi based on 2-pyridin-2-ylethanamine and benzimidazo [2,1-a]benz[de]isoquinoline-7-one-12-carboxylic acid

A new fluorescent probe X based on 2-pyridin-2-ylethanamine and benzimidazo[2,1-a]benz[de]isoquinoline-7-one-12-carboxylic acid was designed and synthesized for the detection of Fe³⁺ and PPi.