Bis-Schiff base as a donor–acceptor fluorescent probe: Recognition of Al3+ ions in near 100% aqueous solution

Synthesis of a super-low detection limit fluorescent probe for Al3+ and its application in fluorescence imaging of zebrafish and cells

A novel fluorescent probe N'-(2-hydroxybenzylidene)-indole-3-formylhydrazine (JHK) was designed and synthesized based on the condensation reaction of indole-3-formylhydrazine and salicylaldehyde. The probe JHK solution could highly selectively recognize Al3+ by the obvious fluorescence enhancement (288-fold) after adding Al3+. And the probe solution with Al3+ had a very high fluorescence quantum yield (89.29 %). The detection limit was calculated to be 1.135 nM, which was significantly lower than many reported detection limits, indicating that the probe JHK had pretty good sensitivity. The ratio of JHK to Al3+ (1:1) and the sensing mechanism were determined by Job's plot, 1H NMR spectra, FTIR spectra, ESI-MS and Gaussian calculation. The probe solution and medium-speed filter paper were successfully used to make test papers for more convenient detection of Al3+. Furthermore, the probe JHK had been successfully applied to the detection of Al3+ in real water, zebrafish and living cells.

A naked-eye visible aluminium (III)-based complex fluorescence sensor for sensitive detection of mesotrione

Mesotrione, which is a kind of herbicide to control broad-leaved weeds, has been increasingly used due to its excellent selectivity, rapid process and low toxicity. However, the excessive application of mesotrione have led to widespread contamination. Herein, a turn-on competitive coordination-based fluorescent probe, 2-hydroxy-1-(9-purin)-methylidenehydrazinenaphthalene (HPM), has been successfully synthesized. HPM could effectively detect Al3+ in CH3OH/HEPES (1/9, v/v) with low limit of detection (LOD) being 0.2 µM via coordination. HPM also exhibited excellent imaging capabilities for Al3+ in living cells with low cytotoxicity. On the basis of the competitive coordination of HPM with Al3+, the [HPM-Al3+] complex could also serve as a potential fluorescence sensor for detecting mesotrione with the LOD of 0.2 µM. Furthermore, [HPM-Al3+] complex was applied for the detection of mesotrione in real samples and test paper. Finally, the mechanism of [HPM-Al3+] for sensing mesotrione was investigated deeply as well. This work designed a new convenient method for on-site detection of mesotrione without the large-scale equipment or complicated pre-treatment.

Isolation of the Flavonoid from Bamboo Residues and Its Application as Metal Ion Sensor in Vitro

Fluorescence sensors prepared from natural polymers have received increasing attention based on their luminescence characteristics for bioimaging, cell imaging, and intracellular detection of inorganic metabolites. In this work, flavonoids isolated from bamboo residues (BRF) were applied as fluorescence sensors for different metal cations' detection in vitro. Results showed the optimal flavonoids extraction condition of solid to liquid ratio, ethanol concentration, extraction time and temperature were determined at 1:25, 50%, 240 min and 90 °C, respectively, resulting in an extraction yield with 104.7 mg/100 g bamboo residues. The BRF is mainly composed of isoorientin, isovitexin, pinosylvin, tricin and isorhamnetin by liquid chromatography-mass spectrometry (LC-MS) analysis. It is found that the BRF displayed strong blue-green emission as well as notable excitation, which can selectively and sensitively detect Fe3+ with the limit of detection (LOD) as low as 38.0 nM. In the Fe3+ detection was no obvious interference by other cations except for Al3+. In addition, the BRF displayed excellent biocompatibility that can be applied to bioimages of the intracellular detection of Fe3+ in L02 cells. Finally, it is found that the BRF possessed significant antioxidant properties in scavenging H2O2-induced endogenous reactive oxygen species (ROS) in a zebrafish module (in vivo) and L02 cells (in vitro). These results showed that the flavonoid products sustainably isolated from an abundant lignocellulosic waste appear to be effective fluorescent sensors for Fe3+ detection in biological systems with excellent biocompatibility and antioxidant activity.

A Naphthalimide-Based Fluorescence "Off-on-Off" Chemosensor for Relay Detection of Al3+ and ClO. Front Chem 2019;7:549. [PMID: 31428604 PMCID: PMC6687763 DOI: 10.3389/fchem.2019.00549]

A novel Al³⁺ chemosensor NPA was designed and synthesized on basis of the mechanism of ICT and CHEF. Upon addition of Al³⁺, the probe NPA displayed a bright green fluorescence under UV radiation and visual color change from yellow to colorless. Spectrum titrations showed that NPA could be recognized as a fluorescent turn-on probe with 10^-8 M detection level. The probe was successfully applied in real water sample and test paper. More important, NPA-Al³⁺ complex were used as a fluorescent turn-off probe for the detection of ClO^- with the detection as low as 2.34 × 10^-8 M. The performance of NPA to Al³⁺ and NPA-Al³⁺ complex to ClO^- demonstrated that NPA could be served as a sensitive probe and exhibit INHIBIT logic gate behavior with Al³⁺ and ClO^- as inputs.

A New “Turn-On” Fluorescence Probe for Al3+ Detection and Application Exploring in Living Cell and Real Samples

An excess of Al3+ will lead to biological disorders and even many diseases. Therefore, detecting the levels of Al3+ in the human body has drawn great attention for health monitoring. The fluorescence method has been broadly applied because of high sensitivity, real-time detection, and intracellular imaging. In this work, a new probe with “turn-on” fluorescence based on Schiff base derivative, 3,6-imine-triphenylamine-(9-ethyl) carbazole (ITEC), has been successfully synthesized and studied. The high selectivity and sensitivity of ITEC to Al3+ were verified by fluorescence spectra and the detection limit was 2.19 nmol/L. A 1:2 stoichiometry of ITEC-Al3+ was obtained by the 1H NMR spectra and Job’s plot. Furthermore, ITEC was successfully applied to the detection of Al3+ with different concentrations in living HeLa cells. The analog experiments about nature contamination of Al3+ in cells and real samples were finished.

A high performance 2-hydroxynaphthalene Schiff base fluorescent chemosensor for Al3+ and its applications in imaging of living cells and zebrafish in vivo

Developing high performance fluorescent chemo-sensors for in vitro and in vivo Al³⁺ detection is highly desirable, because Al³⁺ accumulation has been involved to various diseases. Herein, we report a highly selective and sensitive Schiff base fluorescent probe, H₃L, based on 2-hydroxynaphthalene, which can recognize aluminum ions and exhibit an "off-on" mode with high selectivity in methanol solutions. The detection limit of the probe for Al³⁺ is as low as 10^-7 M which was determined by fluorescent titration. The high selectivity and high sensitivity of H₃L for Al³⁺ are attributed to the inhibition of ESIPT. Additionally, the distribution of intracellular Al³⁺ ions could be observed under confocal fluorescence microscopy. Moreover, we also applied H₃L for in vivo detection of Al³⁺ ions in living zebrafish larvae.

A novel chemosensor based on rhodamine and azobenzene moieties for selective detection of Al3+ ions

Both rhodamine and azobenzene moieties have been conjugated to prepare a novel chemosensor for the detection of Al³⁺ through CHEF-PET and the spirolactam ring opening mechanism.

A highly selective colorimetric and fluorescent turn-on chemosensor for Al(3+) based on naphthalimide derivative

A new chemosensor L based on the naphthalimide moiety was synthesized and characterized. L exhibited the high selectivity and sensitivity for Al(3+) in CH3OH, along with colorimetric and fluorometric dual-signaling responses based on the joint contribution of the ICT and CHEF processes. A 1:1 stoichiometry for the L-Al(3+) complex was formed with an association constant of 7.6×10(4)M(-1), and the limit of detection for Al(3+) was determined as 6.9μM. In addition, L was successfully applied to the determination of Al(3+) in real water samples.

A review of mechanisms for fluorescent ‘‘turn-on’’ probes to detect Al3+ ions

The adverse effect of Al³⁺ ions on human health as well as the environment makes it desirable to develop sensitive and specific techniques for the detection of Al³⁺ ions.