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Photodynamic therapy is an emerging tumor therapy that kills tumor cells by activating reactive oxygen species (ROS) produced by photosensitizers. Mitochondria, as an important organelle, are the main generator of cellular ROS. Therefore, the development of photosensitizers capable of targeting mitochondria could significantly enhance the efficacy of photodynamic therapy. In this study, two novel ruthenium(II) complexes, Ru-1 and Ru-2, were designed and synthesized, both of which were functionalized with α,β-unsaturated ketones for sensing of glutathione (GSH). The crystal structures of the two complexes were determined and they exhibited good recognition of GSH by off–on luminescence signals. The complex Ru-2 containing aromatic naphthalene can enter the cells and react with GSH to generate a strong luminescence signal that can be used to monitor intracellular GSH levels through imaging. Ru-2 also has an excellent mitochondrial localization ability with a Pearson's coefficient of 0.95, which demonstrates that it can efficiently target the mitochondria of tumor cells to enhance the effectiveness of photodynamic therapy as a photosensitizer. [ABSTRACT FROM AUTHOR]

GSH is one of the most important reducing agents in biological systems. The depletion of GSH in the human body is linked to many diseases. Therefore, it is necessary to develop suitable and efficient probes for detecting GSH concentrations in real samples. In this work, we designed and synthesized two near-infrared emitting iridium(III) complex probes containing a novel ligand functionalized with an α,β-unsaturated ketone for the rapid and sensitive detection of GSH. The molecular structure of Ir2 was determined by X-ray crystallography. Due to their large Stokes shift, long luminescence lifetime and NIR emission, these probes were successfully applied in the imaging of GSH in living cells. In addition, two iridium(III) complexes have strong singlet oxygen generation ability which can be used for photodynamic therapy (PDT) upon visible light irradiation. On the basis of these findings, our iridium(III) complexes may serve as GSH probes for HeLa cell imaging and as photosensitizers for PDT. [ABSTRACT FROM AUTHOR]

In this work, barbituric acid-modified graphitic carbon nitride (BCN) nanosheets with blue-green fluorescence were prepared by a copolymerization of dicyandiamide with barbituric acid and then by a chemical oxidation process. A ratiometric fluorescent sensor for Cu2+ was designed by using BCN nanosheets as the report probe and Ru(bpy)3Cl2 as the reference probe. In the presence of different concentrations of Cu2+, the blue-green fluorescence of BCN nanosheets was drastically quenched, while the red fluorescence of Ru(bpy)3Cl2 remained constant. The color of the sensor changed from blue-green to red, resulting in ratiometric and visual detection of Cu2+ ions. The detection limit for Cu2+ was estimated to be 70 nM, and as low as 5 μM Cu2+ was distinguished with the naked eye. Additionally, this sensor was also applied for the detection of Cu2+ in tap water samples. [ABSTRACT FROM AUTHOR]

A sensitive assay was demonstrated for the colorimetric and luminescent detection of heparin. Positively charged [Ru(phen)2np]2+ (np: naphtho[2,3-f][1,10]phenanthroline) can interact with negatively charged AuNPs through electrostatic interaction, leading to the luminescence quenching of [Ru(phen)2np]2+via energy transfer as well as the aggregation of AuNPs together with a color change in solution from red to blue. Upon the addition of negatively charged heparin to gold nanoparticles functionalized by ruthenium(ii) complexes, the emission of [Ru(phen)2np]2+ recovered due to the competitive adsorption of [Ru(phen)2np]2+ to heparin and AuNPs. A linear calibration curve was obtained in the 0.4 μM to 100 μM range and 0.1 μM to 6 μM with a low detection limit of 0.22 μM and 0.024 μM based on 3σ/s for heparin quantification in buffer solution and in 1% fetal bovine serum (FBS), respectively. Interestingly, the naked eye alone can judge the presence of 0.02 μM heparin without the aid of any advanced instruments by color change. Thus a convenient and visual method to detect heparin was established. [ABSTRACT FROM AUTHOR]

Mononuclear ruthenium complex 1and dinuclear complex 2were synthesized by reaction of the appropriate bidentate pyrazolyl-pyridyl-based ligand L (L = 1,4-bis(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene) with cis-Ru(bipy)2Cl2·2H2O. They were characterized by elemental analyses, ESI-MS, 1H spectroscopy, and X-ray crystallography for 2. Compounds 1and 2both emit strongly in solid states and in solutions at 298 K with the lifetimes in the microsecond range. Electrogenerated chemiluminescence (ECL) of complexes 1and 2in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) at different working electrodes in acetonitrile and phosphate buffer solutions (PBS, pH 7.5) was studied. The ECL spectra are identical to the photoluminescence spectra, indicating that the ECL emissions are due to the metal to ligand charge transfer (MLCT). In all cases, ECL quantum efficiencies of dinuclear complex 2are higher than those of mononuclear complex 1, and ECL quantum efficiencies of complexes 1and 2/TPrA system are higher than those of DBAE system. It is noted that diuretic furosemide tends to decrease the ECL intensity of complex 2/TPrA system in PBS (pH 7.5) at GC working electrode. A novel ECL method for the determination of diuretic furosemide was developed with a linear range between 2.0 × 10−7mol L−1and 1.0 × 10−6mol L−1, and a detection limit of 1.2 × 10−8mol L−1based on 3 times the ratio of signal-to-noise. [ABSTRACT FROM AUTHOR]

In this work, barbituric acid-modified graphitic carbon nitride (BCN) nanosheets with blue-green fluorescence were prepared by a copolymerization of dicyandiamide with barbituric acid and then by a chemical oxidation process. A ratiometric fluorescent sensor for Cu2+ was designed by using BCN nanosheets as the report probe and Ru(bpy)3Cl2 as the reference probe. In the presence of different concentrations of Cu2+, the blue-green fluorescence of BCN nanosheets was drastically quenched, while the red fluorescence of Ru(bpy)3Cl2 remained constant. The color of the sensor changed from blue-green to red, resulting in ratiometric and visual detection of Cu2+ ions. The detection limit for Cu2+ was estimated to be 70 nM, and as low as 5 μM Cu2+ was distinguished with the naked eye. Additionally, this sensor was also applied for the detection of Cu2+ in tap water samples. [ABSTRACT FROM AUTHOR]

Photodynamic therapy is an emerging tumor therapy that kills tumor cells by activating reactive oxygen species (ROS) produced by photosensitizers. Mitochondria, as an important organelle, are the main generator of cellular ROS. Therefore, the development of photosensitizers capable of targeting mitochondria could significantly enhance the efficacy of photodynamic therapy. In this study, two novel ruthenium(II) complexes, Ru-1 and Ru-2, were designed and synthesized, both of which were functionalized with α,β-unsaturated ketones for sensing of glutathione (GSH). The crystal structures of the two complexes were determined and they exhibited good recognition of GSH by off-on luminescence signals. The complex Ru-2 containing aromatic naphthalene can enter the cells and react with GSH to generate a strong luminescence signal that can be used to monitor intracellular GSH levels through imaging. Ru-2 also has an excellent mitochondrial localization ability with a Pearson's coefficient of 0.95, which demonstrates that it can efficiently target the mitochondria of tumor cells to enhance the effectiveness of photodynamic therapy as a photosensitizer.

GSH is one of the most important reducing agents in biological systems. The depletion of GSH in the human body is linked to many diseases. Therefore, it is necessary to develop suitable and efficient probes for detecting GSH concentrations in real samples. In this work, we designed and synthesized two near-infrared emitting iridium(III) complex probes containing a novel ligand functionalized with an α,β-unsaturated ketone for the rapid and sensitive detection of GSH. The molecular structure of Ir2 was determined by X-ray crystallography. Due to their large Stokes shift, long luminescence lifetime and NIR emission, these probes were successfully applied in the imaging of GSH in living cells. In addition, two iridium(III) complexes have strong singlet oxygen generation ability which can be used for photodynamic therapy (PDT) upon visible light irradiation. On the basis of these findings, our iridium(III) complexes may serve as GSH probes for HeLa cell imaging and as photosensitizers for PDT.

In this work, barbituric acid-modified graphitic carbon nitride (BCN) nanosheets with blue-green fluorescence were prepared by a copolymerization of dicyandiamide with barbituric acid and then by a chemical oxidation process. A ratiometric fluorescent sensor for Cu2+ was designed by using BCN nanosheets as the report probe and Ru(bpy)3Cl2 as the reference probe. In the presence of different concentrations of Cu2+, the blue-green fluorescence of BCN nanosheets was drastically quenched, while the red fluorescence of Ru(bpy)3Cl2 remained constant. The color of the sensor changed from blue-green to red, resulting in ratiometric and visual detection of Cu2+ ions. The detection limit for Cu2+ was estimated to be 70 nM, and as low as 5 μM Cu2+ was distinguished with the naked eye. Additionally, this sensor was also applied for the detection of Cu2+ in tap water samples.

Surface functionalization of nanomaterials with highly specific recognition elements, such as biomolecules and organic molecules, has made possible many novel nanosensors for bio/chemical analysis and target bioimaging. In this report, a fluorescent nanosensor which exhibits highly specific recognition capability towards Zn 2+ over competing metal ions has been developed through covalently functionalizing carbon dots (C-dots) with the quinoline derivatives which show response to Zn 2+ . The nanosensor exhibits excellent water solubility, biocompatibility, and cell-membrane permeability, and demonstrates high selectivity towards Zn 2+ with a detection limit as low as 6.4 nM. Additionally, the rapid response of the nanosensor towards Zn 2+ can be achieved within 1 min. The large amount of recognition units on the outer surface of an individual nanoparticle enables the signal amplification, hence making the immediate and highly sensitive detection of Zn 2+ possible. Therefore, a reliable and highly specific nanosensor has been demonstrated for both rapid quantitative detection of Zn 2+ in aqueous solution and real-time imaging of intracellular Zn 2+ , suggesting its potential and significance in bioanalysis and biomedical detection in the future.

Four ruthenium(II) complexes, [Ru(bpy)2L1](PF6)2, [Ru(bpy)2L2](PF6)2, [Ru(dmb)2L1](PF6)2, and [Ru(dmb)2L2](PF6)2, where bpy = 2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, L1 = 4-methyl-2,2'-bipyridine-4'-carboxaldehyde, and L2 = 4,4'-diformyl-2,2'-bipyridine, have been characterized for sensing cyanide based on the well-known formation of cyanohydrins. The structure of [Ru(dmb)2L2](PF6)2 is also determined by single crystal X-ray diffraction. Their cyanide anion binding properties in pure and aqueous acetonitrile solution were thoroughly examined by UV-Vis absorption and photoluminescence (PL) spectroscopy. Upon the addition of cyanide to the solution of ruthenium(II) complexes at 298 K, a color change from orange to yellow and a luminescent variation from dark red to red-orange can be observed by the naked eye. The large blue shift of the absorption and emission spectra and significant enhancement of the emission intensity upon the addition of cyanide could be attributed to the formation of a cyanohydrin group by the selective reaction of the aldehyde group of the ruthenium(II) complexes with cyanide. Importantly, these kinds of ruthenium(II) complexes show a unique recognition of cyanide ions over other anions. The results reveal that this kind of ruthenium(II) complex containing an aldehyde group is an eligible sensor for cyanide anions.

Three new mononuclear copper(II) complexes, [Cu(L2)](2+) (1), [Cu(acac)(L)](+) (2), and [Cu(acac-Cl)(L)](+) (3) (L = 2-(4-pyridine)oxazo[4,5-f]1,10-phenanthroline (4-PDOP); acac = acetylacetone; acac-Cl = 3-chloroacetylacetone), have been synthesized and characterized by elemental analysis, high resolution mass spectrometry (Q-TOF), and IR spectroscopy. Two of the complexes were structurally characterized by single-crystal X-ray diffraction techniques. Their interactions with DNA were studied by UV-vis absorption and emission spectra, viscosity, thermal melting, DNA unwinding assay and CD spectroscopy. The nucleolytic cleavage activity of the compounds was carried out on double stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment in the presence and absence of an oxidant (H2O2). Active oxygen intermediates such as hydroxyl radicals and hydrogen peroxide generated in the presence of L and complexes 1-3 may act as active species for the DNA scission. The cytotoxicity of the complexes against HepG2 cancer cells was also studied.

Two water soluble Re(I) tricarbonyl diimine complexes containing cationic 2,2'-bipyridyl ligands [Re(L1)(CO)(3)(AN)](2+) (1) and [Re(L2)(CO)(3)(AN)](3+) (2) (L1 and L2: a cationic 2,2'-bipyridyl ligand, AN: acetonitrile) were synthesized and characterized. Their photophysical, electrochemical and electrochemiluminescent properties were investigated. The crystal structures of the two complexes have also been determined. Electrochemiluminescence (ECL) of the two complexes 1 and 2 have been studied in aqueous buffer solution in the presence of co-reactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) at a Au working electrode. The ECL behavior of the complexes was also studied in the presence of several surfactants such as Triton X-100 and Zonyl FSN. The ECL signals of the rhenium(I) complex were enhanced about 190-fold and 70-fold at a Au electrode in the presence of Triton X-100 for the [Re(L1)(CO)(3)(AN)](2+)/TPrA and [Re(L1)(CO)(3)(AN)](2+)/DBAE systems, respectively.

Mononuclear ruthenium complex 1 and dinuclear complex 2 were synthesized by reaction of the appropriate bidentate pyrazolyl-pyridyl-based ligand L (L = 1,4-bis(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene) with cis-Ru(bipy)(2)Cl(2)·2H(2)O. They were characterized by elemental analyses, ESI-MS, (1)H spectroscopy, and X-ray crystallography for 2. Compounds 1 and 2 both emit strongly in solid states and in solutions at 298 K with the lifetimes in the microsecond range. Electrogenerated chemiluminescence (ECL) of complexes 1 and 2 in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) at different working electrodes in acetonitrile and phosphate buffer solutions (PBS, pH 7.5) was studied. The ECL spectra are identical to the photoluminescence spectra, indicating that the ECL emissions are due to the metal to ligand charge transfer (MLCT). In all cases, ECL quantum efficiencies of dinuclear complex 2 are higher than those of mononuclear complex 1, and ECL quantum efficiencies of complexes 1 and 2/TPrA system are higher than those of DBAE system. It is noted that diuretic furosemide tends to decrease the ECL intensity of complex 2/TPrA system in PBS (pH 7.5) at GC working electrode. A novel ECL method for the determination of diuretic furosemide was developed with a linear range between 2.0 × 10(-7) mol L(-1) and 1.0 × 10(-6) mol L(-1), and a detection limit of 1.2 × 10(-8) mol L(-1) based on 3 times the ratio of signal-to-noise., (This journal is © The Royal Society of Chemistry 2011)

A simple, selective and sensitive turn-on fluorescent sensor for the detection of mercury(II) ion was developed using Sybr Green I as the signal reporter and SWCNTs as the quencher. Due to the affinity of SWCNTs towards ssDNA and organic dye, Sybr Green I, thymine-rich ssDNA and SWCNTs could form a self-assembly of three components, resulting in fluorescence quenching. Upon addition of another thymine-rich ssDNA and mercury(II) ion, formation of dsDNA via T-Hg(2+)-T base pairs enabled Sybr Green I to intercalate into the dsDNA, resulting in the restoration of fluorescence. SWCNTs were found to reduce the background signal and improve the analytical sensitivity. A linear relationship between the fluorescence intensity and the concentration of mercury(II) ion was observed in the range of 20-1250 nM (R = 0.9985) with a detection limit of 7.9 nM. The proposed method was applied to detect mercury(II) ion in tap water samples with good results.

A new water-soluble iridium(III) diimine complex with appended sugar was synthesized and characterized. The electrochemiluminescent behavior of the new complex in aqueous buffer was first studied and the ECL signal was found to be much higher than that of [Ru(bpy)(3)](2+) at a Pt working electrode. Tri-n-propylamine (TPA) and antibiotics were determined by the ECL of the iridium(III) complex in aqueous buffer at the Pt electrode and the method was found to show good sensitivity and reproducibility. The new iridium(III) complex was found to display good solubility in aqueous solution and a strong ECL signal at the Pt electrode, which might open up the possibility of its application in analysis.