A single molecular probe for multi-analyte (Cr³⁺, Al³⁺ and Fe³⁺) detection in aqueous medium and its biological application

Application of a Novel "Turn-on" Fluorescent Material to the Detection of Aluminum Ion in Blood Serum

A novel "turn-on" fluorescent bioprobe, 1,2,3,4,5-penta(4-carboxyphenyl)pyrrole sodium salt (PPPNa), with aggregation-enhanced emission characteristics was synthesized for the in situ quantitative detection of Al³⁺ in serum. It exhibited a high selectivity to Al³⁺ in both simulated serum and fetal calf serum with no interferences from other metal ions or serum components observed and no isolation required. A weak interaction between PPPNa and serum albumin was found, which caused no interference, but enhanced fluorescence response of PPPNa to Al³⁺ and improved detection sensitivity. The limit of detection was determined to be 1.50 μmol/L Al³⁺ in phosphate-buffered saline solution containing 33 μg/mL bovine serum albumin (BSA) and decreased to 0.98 μmol/L as BSA concentration increased to 100 μg/mL. The fluorescence "turn-on" mechanism of the PPPNa probe to detect Al³⁺ was proposed. A bidentate complex is formed between the carboxy group of PPPNa and Al³⁺, causing the photoluminescence (PL) emission enhancement by aggregation. BSA chains further strengthen the stacking compactness of the aggregates of PPPNa and Al³⁺ and consequently enhance the PL emission of PPPNa by further promoting the restriction of intramolecular rotation of the phenyl ring. Its application to the in situ Al³⁺ was successfully demonstrated with HeLa cells and NIH 3T3 cells. The low cytotoxicity and highly selective response of PPPNa to Al³⁺ endow its great potentials to in vivo detecting and imaging of Al³⁺ as well as an absorbent of Al³⁺.

A novel turn-on fluorescent probe for Al3+ and Fe3+ in aqueous solution and its imaging in living cells

A quinoline-based fluorescence probe has been prepared and characterized. Probe 1 showed a selective sensing ability for Al³⁺ and Fe³⁺ ions through fluorescence enhancement response at 515nm when it was excited at 360nm. In the presence of Fe³⁺ ion, probe 1 exhibited a detection limit of 2.10×10^-6M. As for Al³⁺, its detection limit of 3.58×10^-7M was significantly lower than the highest limit of Al³⁺ in drinking water recommended by the WHO (7.41μM), representing a rare example in reported fluorescent probe for Al³⁺ ion. The fluorescence microscopy experiments have demonstrated that probe 1 could be used in live cells for the detection of Al³⁺ and Fe³⁺ ions.

Excited-state intramolecular proton-transfer (ESIPT) based fluorescence sensors and imaging agents

We review recent advances in the design and application of excited-state intramolecular proton-transfer (ESIPT) based fluorescent probes. These sensors and imaging agents (probes) are important in biology, physiology, pharmacology, and environmental science.

A three-dimensional (time, wavelength and intensity) functioning fluorescent probe for the selective recognition/discrimination of Cu2+, Hg2+, Fe3+ and F− ions

A new probe for the selective recognition/discrimination of Cu²⁺, Hg²⁺, Fe³⁺ and F⁻ ions by measuring their response time, wavelength and fluorescence intensity.

An ampyrone based azo dye as pH-responsive and chemo-reversible colorimetric fluorescent probe for Al3+ in semi-aqueous medium: implication towards logic gate analysis

A novel ampyrone based azo dye, 4-((6-hydroxybenzo[d][1,3]dioxol-5-yl)diazenyl)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (1), was synthesized by coupling sesamol and 4-amino antipyrine (ampyrone).

Specific recognition of Cr3+ under physiological conditions by allyl substituted appendage rhodamine and its cell-imaging studies

An allyloxynitrophenylimio-propylhydroxyl appended rhodamine (RD-3) specifically recognises Cr³⁺ in aqueous buffer medium at pH 7.4. The visible light excitable reagent (λ_ex 505 nm) on selective binding to Cr³⁺ exhibited a strong fluorescence turn-on response with powerful emission at 557 nm and the tail of this luminescence band is extended to ∼650 nm. Interference studies confirm that other metal ions (27 ions) do not hamper the detection process of Cr³⁺. The sensing mechanism is studied by absorption, fluorescence, Job's plot, and ¹H NMR titration studies. The detection limit is as low as 33 nM. The practical applicability of RD-3 is examined for imaging Cr(iii) ions in HCT116 (human colorectal carcinoma) cells.

Resorcin[4]arene-Based Microporous Metal-Organic Framework as an Efficient Catalyst for CO2 Cycloaddition with Epoxides and Highly Selective Luminescent Sensing of Cr2O72

A stable microporous anionic metal-organic framework (MOF), [(CH₃)₂NH₂]₆[Cd₃L(H₂O)₂]·12H₂O (1), has been synthesized via solvothermal assembly of a new resorcin[4]arene-functionalized dodecacarboxylic acid (H₁₂L) and Cd(II) cations. The constructed MOF (1) was characterized by single-crystal X-ray diffraction and other physicochemical analyses. 1 exhibits a fascinating 3D microporous framework structure, in which the free water molecules and the [(CH₃)₂NH₂]⁺ cations were located. Remarkably, the exposed Lewis acid Cd(II) sites of activated 1 make it an efficient heterogeneous catalyst for the cycloaddition of CO₂ with epoxides at 1 and 20 atm. Importantly, the activated samples of 1 can be reused at least five circles with excellent catalytic performance. Moreover, the fluorescence detection of Cr₂O₇^2- and Fe³⁺ was studied by using 1 as a potential luminescent sensor.

Facile synthesis of a water-soluble fluorescence sensor for Al3+ in aqueous solution and on paper substrate

In this study, a facile water-soluble fluorescence sensor 2-((2-hydroxybenzylidene)-amino)-2-(hydroxymethyl)propane-1,3-diol (ST) was synthesized via one-step reaction, and its fluorescence sensing performance for Al³⁺ both in aqueous solution and on paper substrate was evaluated. The results showed that ST exhibited an specific fluorescence "turn-on" response to Al³⁺ over other cations in aqueous solution as well as on the test paper. The limit of detection was found to be 3.2×10^-7M, which revealed that the obtained Schiff-base based fluorescence chemosensor ST possessed a great potential for the rapid, quantitative and qualitative detection of Al³⁺.

Intracellular detection of hazardous Cd2+ through a fluorescence imaging technique by using a nontoxic coumarin based sensor

A new coumarin based turn on fluorescent sensor (R1) was reported for the detection of highly hazardous Cd²⁺ with excellent selectivity and sensitivity without any interference of other metal ions.

A rhodamine based fluorescent trivalent sensor (Fe3+, Al3+, Cr3+) with potential applications for live cell imaging and combinational logic circuits and memory devices

A novel sensor (HL5) recognizes sensitively and selectively trivalent metal ions M³⁺ (M = Al, Fe and Cr) with prominent enhancement in emission intensities with logic gate circuits and memory devices with living cell imaging application.

Recognition of Mg²⁺ by a new fluorescent "turn-on" chemosensor based on pyridyl-hydrazono-coumarin

A new fluoroionophore PyHC bearing 2-pyridylhydrazone and 7-hydroxycoumarin moieties for selective detection of Mg(2+) was synthesized and characterized. This chemosensor exhibited "turn-on" fluorescence behavior and was sensitive to Mg(2+) concentrations as low as 105 nmol L(-1) in ethanol-water solution. Detailed spectroscopic studies revealed the binding mode of a 1:1 complex between PyHC and Mg(2+) that leads to a fluorescence enhancement.

Selective interactions of trivalent cations Fe³⁺, Al³⁺ and Cr³⁺ turn on fluorescence in a naphthalimide based single molecular probe

Synthesis and fluorescence turn-on behavior of a naphthalimide based probe is described. Selective interactions of trivalent cations Fe(3+), Al(3+) or Cr(3+) with probe 1 inhibit the PET operating in the probe, and thereby, permit the detection of these trivalent cations present in aqueous samples and live cells. Failure of other trivalent cations (Eu(3+), Gd(3+) and Nb(3+)) to inhibit the PET process in 1 demonstrates the role of chelating ring size vis-à-vis ionic radius in the selective recognition of specific metal ions.

Small heterocycles as highly luminescent building blocks in the solid state for organic synthesis

ESIPT photoactive mono-formylated benzoxazole derivatives obtained through a Duff functionalization protocol using a simple synthetic methodology.

A novel 2-(2′-aminophenyl)benzothiazole derivative displays ESIPT and permits selective detection of Zn2+ ions: experimental and theoretical studies

Synthesis of a novel 2-(2′-aminophenyl)benzothiazole based probe (1) and demonstration of excited state intramolecular proton transfer (ESIPT) with a large Stokes shift (∼246 nm) are presented.

A multi-responsive turn-on flurogenic probe to sense Zn2+, Cd2+and Pb2+: left-right-center emission signal swing

A rationally designed multi-target probe can sense Zn²⁺, Cd²⁺and Pb²⁺through individual TURN-ON emission signals in physiological pH with signal swing.

Facile preparation of pH-responsive AIE-active POSS dendrimers for the detection of trivalent metal cations and acid gases

AIE-active POSS dendrimers, exhibiting AIE effects and pH-responsive properties, were employed as sensitive fluorescent probes for trivalent metal cations and acid gases.

Visual detection of Al(3+) ions using conjugated copolymer-ATP supramolecular complex

A colorimetric Al(3+) sensor based on fluorescence recovery of a conjugated copolymer-ATP complex is proposed. An optimized ratio of two polythiophene (PT) monomers is utilized to synthesize copolymer (CP) that yielded maximized colorimetric response for Al(3+) in deionized (DI) and tap water. The electrostatic disassembly of CP-ATP upon addition of Al(3+) led to an evident visual color change. The lowest concentration of Al(3+) for naked eye observation is around 4 μM, which is below the threshold levels in drinking water according to European Economic Community (EEC) standard. Besides, the proposed assay showed a similar response to Al(3+) in tap water. The proposed methodology showed selective and sensitive detection for Al(3+) in analytically relevant concentration ranges without involving sophisticated instrumentation, illustrating the applicability for on-site drinking water monitoring.

Single Chemosensor for Double Analytes: Spectrophotometric Sensing of Cu(2+) and Fluorogenic Sensing of Al(3+) Under Aqueous Conditions

(E)-N-((8-Hydroxy-1,2,3,5,6,7-hexahydropyrido-[3,2,1-ij]-quinolin-9-yl)methylene)-4-tert-butyl -benzhydrazide has been developed as a single, dual-functional chemosensor. The chemosensor showed a good selectivity and sensitivity toward to Al(3+) and Cu(2+) at a low detection limit, respectively. Theoretical calculations have also been carried out to understand the configuration of the complexes.

A highly selective fluorescent sensor for Al3+ and the use of the resulting complex as a secondary sensor for PPi in aqueous media: its applicability in live cell imaging

An “off–on–off” reversible fluorescent sensor has been developed for sequential detection of Al³⁺ and PPi in aqueous media, and has further been applied to live cell imaging.

NBD-based fluorescent chemosensor for the selective quantification of copper and sulfide in an aqueous solution and living cells

A fluorescent chemosensor (NL) has been developed for the selective quantification of copper and sulfide in aqueous solutions and living cells.

A differentially selective molecular probe for detection of trivalent ions (Al3+, Cr3+and Fe3+) upon single excitation in mixed aqueous medium

A chemosensor was developed which could selectively detect and differentiate trivalent metal ions (Al³⁺, Cr³⁺and Fe³⁺) upon single excitation at two different wavelengths in aqueous medium.

A water-stable lanthanide-functionalized MOF as a highly selective and sensitive fluorescent probe for Cd2+

A highly selective and sensitive fluorescent sensor for Cd²⁺in aqueous solution based on a lanthanide post-functionalized metal–organic framework was developed.

Click synthesis of a novel triazole bridged AIE active cyclodextrin probe for specific detection of Cd2+

A novel aggregation induced emission (AIE) active cyclodextrin (CD) was synthesized via click chemistry, which is the first reported clicked AIE probe for the specific detection of Cd²⁺.

An easy and accessible water-soluble sensor for the distinctive fluorescence detection of Zn2+ and Al3+ ions

A water-soluble fluorescence sensor was facilely synthesized and it can be used for the distinctive fluorescence detection of Zn²⁺ and Al³⁺ ions.

Binding site-driven sensing properties of a quinazoline derivative with metal cations

A quinazoline derivative showed high sensitivity and selectivity for Al³⁺, Cr³⁺ and Fe³⁺ ions in methanol solution.