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Fungal keratitis (FK) is a refractory ophthalmic disease that can result in vision impairment and even blindness due to the severe fungal invasiveness and excessive inflammatory response. Therefore, antifungal treatment combined with local immunosuppressive therapy is regarded as the most effective strategy to improve the clinical outcome of FK. Oxidized polysaccharides with aldehyde groups possess obvious inhibitory activity towards microorganisms. Herein, we use chondroitin sulfate (CS), a recognized anti-inflammatory biopolysaccharide, to prepare oxidized chondroitin sulfate (OCS) via sodium periodate (NaIO4) oxidation for the treatment of FK. The chemical structure of OCS was characterized by FTIR, 1H NMR, and XPS, revealing that the O-dihydroxy in the D -glucuronic acid unit of CS was selectively broken by NaIO4, forming active aldehyde groups. The introduction of aldehydes not only retains the anti-inflammatory activity but also confers OCS with antifungal property. In vitro antifungal experiments showed that OCS inhibits the growth, represses the biofilm formation and alters the membrane integrity of A. fumigatus. The toxicity of OCS was evaluated by cytotoxicity tests (CCK-8) and the Draize eye test in vitro and in vivo. qRT-PCR confirmed that OCS had similar anti-inflammatory activity as CS. In mice with A. fumigatus keratitis, OCS versus CS or PBS showed an excellent therapeutic effect, characterized by a lower corneal inflammation score, less fungal load, reduced neutrophil recruitment, and the downregulated expression of pro-inflammatory factors. Our findings demonstrate that OCS improves the prognosis of A. fumigatus keratitis in mice by inhibiting the growth of fungi, reducing the recruitment of neutrophils and inhibiting the inflammatory response. It provides innovative ideas for the development and application of OCS in medicine and biomaterials fields. [ABSTRACT FROM AUTHOR]

A new and simple surface-enhanced Raman scattering (SERS) biosensor based on the tyramine signal amplification (TSA)-triggered formation of horseradish peroxidase (HRP) repeats on a gold sensing chip was designed for the highly sensitive detection of hydrogen peroxide (H2O2). Initially, gold wafers were functionalized with HRP as sensing chips. Then, the HRP immobilized on the chips triggers the TSA reaction to transform the tyramine–HRP conjugate into a tyramine–HRP repeat array. With the aid of the target H2O2, the HRP repeats catalyze the oxidation of o-phenylenediamine (OPD) and produce an enzyme catalytic product with a different chemical structure, thus altering the fingerprint of the SERS spectra from that of OPD. H2O2 can be quantitatively analyzed according to the change in SERS signal intensity. On the basis of the TSA strategy, the proposed method allows the detection of H2O2 with a limit of detection (LOD) of 0.8 × 10−8 M. The as-prepared SERS sensor can achieve high-sensitivity H2O2 detection with a small amount of sample for each analysis. Therefore, this sensor exhibits significant potential for application in bioanalysis. [ABSTRACT FROM AUTHOR]

Excited-state intramolecular proton transfer (ESIPT)-based fluorophores with two-photon excitation fluorescence (TPEF) are rare. Our aim with this research was to develop ESIPT-based fluorophores exhibiting TPEF. Herein, we used 4-hydroxyisoindoline-1,3-dione as a scaffold to develop a two-photon fluorescent probe BHID-Bpin, for the detection of peroxynitrite (ONOO−). BHID-Bpin exhibits excellent selectivity, sensitivity, and fast response towards ONOO− in PBS buffer solution (10 mM, pH = 7.40). Additionally, BHID-Bpin displays high photo-stability under two-photon irradiation at 750 nm. Furthermore, the probe can image endogenous ONOO− in HeLa cells and exogenous ONOO− in rat hippocampal slices at a depth of 110 μm. [ABSTRACT FROM AUTHOR]

A three-dimensional metal–organic framework, namely {[Zn3(BIBT)(BTC)5/3(μ3-OH)]·solvents}n (JXUST-4), has been synthesized by using ZnII ions, and BIBT and H3BTC ligands (BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H3BTC = 1,3,5-benzenetricarboxylic acid). JXUST-4 shows a new (3,3,7)-connected topology net containing a trinuclear ZnII cluster, uncoordinated N atoms of BIBT and uncoordinated carboxylate O atoms of H3BTC, which facilitates the interaction between the framework and analytes. Fluorescence studies indicate that JXUST-4 generates light yellow luminescence, which could be ascribed to ligand-centered emission. More importantly, JXUST-4 could be viewed as an effective fluorescent sensor toward acetylacetone through an obvious fluorescence red-shift with high sensitivity, efficient selectivity, and outstanding recycling capacity. Furthermore, the possible sensing mechanism of JXUST-4 toward acetylacetone is due to electron transfer and weak interactions between the analyte and framework. [ABSTRACT FROM AUTHOR]

A new benzothiadiazole-based MOF {[Zn(BIBT)(oba)]·DMA}n (JXUST-3, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2oba = 4,4′-oxybisbenzoate) has been solvothermally synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy and TGA. The fluorescence studies suggest that JXUST-3 could simultaneously selectively sense trivalent metal ions including Al3+, Cr3+ and Fe3+ by a turn-off effect, and the detection limits are 0.055, 0.049 and 0.056 μM, respectively. Moreover, JXUST-3 exhibits relatively good thermal and chemical stabilities and reusability. The fluorescent test paper also displayed an obvious turn-off effect, indicating that JXUST-3 can be used as a potential multi-response fluorescent probe. The possible quenching mechanisms of JXUST-3 for Al3+ and Fe3+ were competitive energy absorption, and for Cr3+ ions, they were competitive energy absorption and weak interactions between Cr3+ and the framework. Therefore, JXUST-3 could be viewed as a transition metal MOF fluorescence sensor for Al3+, Cr3+ and Fe3+ by the turn-off effect, simultaneously. [ABSTRACT FROM AUTHOR]

A one-pot approach has been demonstrated for the synthesis of amorphous luminol–gallium (Ga) nanoassemblies, which are formed by small particles with big irregular spheres or network nanoassemblies. Moreover, luminol–Ga nanoassemblies exhibit peroxidase-mimetic activity toward the oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) owing to its stimulating effect on the formation of reactive oxygen groups, such as hydroxyl radicals (OH˙). After the addition of luminol–Ga nanoassemblies to the TMB–H2O2 system, a remarkable color change is observed from colorless TMB to its blue product TMBox accompanied by an absorption peak at around 652 nm. Owing to the presence of reactive oxygen groups by luminol–Ga nanoassemblies, the peroxidase-mimetic activity is inhibited by PPi. Accordingly, the blue color fades away and the absorbance at 652 nm is decreased. Herein a novel sensitive colorimetric detection of PPi from 0.5 to 15 μM using luminol–Ga nanoassemblies is developed with the limit of detection (LOD) of 62.4 nM. The practicability of the assay toward the detection of PPi is also investigated in real water analysis such as lake water and tap water. Recoveries from 97.3% to 102.6% in local lake water and tap water samples are obtained. Therefore this cost-effective peroxidase-based analysis using luminol–Ga nanoassemblies is a potentially powerful tool for the quantitative determination of PPi in environmental samples. [ABSTRACT FROM AUTHOR]

A novel nonanuclear nickel(II) cluster identified as [Ni9(OH)6(CO3)2(ba)8(Hdmpz)6(DMF)2]·EtOH·2DMF (SD/Ni9a, Hba = benzoic acid, Hdmpz = 3,5-dimethyl-1H-pyrazole) is successfully constructed from mixed ligands. The single-crystal X-ray diffraction (SCXRD) structural analysis confirms the composition and reveals the "drum-like" inner core structure surrounded by ba− and DMF. Six Hdmpz ligands in their neutral form further sandwich the "drum" up and down, and is hydrogen bonded with two carbonate anions that are derived from the atmospheric CO2 with the help of Et3N. Electrospray ionization mass spectrometry (ESI-MS) reveals that the SD/Ni9a maintains an intact core in the solution with a slight exchange of outer ligands. Detailed collision-induced dissociation (CID) experiments reveal the collision energy (CE)-promoted ligand loss and exchange between ba− and Hdmpz. Furthermore, the magnetic study shows that there is no interaction between the Ni centers at room temperature, whereas the ferromagnetic coupling between the Ni centers is found with an S = 3 spin ground state of the cluster at low temperature. Moreover, the UV-vis spectrum and the photocurrent response measurements show its good optical properties with an indirect bandgap of about 2.35 eV and fast current response upon visible light irradiation. [ABSTRACT FROM AUTHOR]

Two new GdIII complexes with the formulas of [Gd(ma)2(H2O)2]·2H2O (1) and {[Gd(ma)(ox)0.5(H2O)]·2H2O}n (2) (H2ma = DL -malic acid and H2ox = oxalic acid) have been successfully prepared by using Gd2O3 or Gd(NO3)3 as metal ion sources. Complex 1 exhibits a discrete mononuclear structure, while complex 2 displays a three-dimensional 'layer-pillar' structure with ox2− anions as pillars that are generated in situ. Magnetic studies suggest the presence of ferromagnetic couplings between the intramolecular or interlayer GdIII ions and large magnetocaloric effects with −ΔS maxm = 32.1 J kg−1 K−1 (1) and 44.6 J kg−1 K−1 (2) for ΔH = 7 T. Therefore, they are good candidates as magnetic refrigerants. [ABSTRACT FROM AUTHOR]

Glutathione (GSH) in tumors consumes 1O2 and seriously inhibits the PDT effect. MnO2-coated porphyrin metal–organic frameworks are developed to realize the oxidation of GSH by MnO2 for enhanced PDT, activated MR imaging, and controllable release of DOX as magnetic resonance imaging guided drug–PDT dual-therapy. [ABSTRACT FROM AUTHOR]

A simple ESIPT-based fluorescence probe (HMBT-LW) was developed for the detection of superoxide (O2Ṗ−). HMBT-LW was synthesised over two steps and was shown to rapidly detect low concentrations of O2Ṗ− (limit of detection = 7.4 μM), fully reacting within two minutes. Furthermore, HMBT-LW demonstrated excellent selectivity and sensitivity towards O2Ṗ−. [ABSTRACT FROM AUTHOR]

Gold nanorods (AuNRs) were conjugated with chlorin e6 (Ce6), a commonly used photosensitizer, to form AuNRs–Ce6 by electrostatic binding. Due to the strong surface plasmon resonance coupling, the fluorescence of conjugated Ce6 was enhanced 3-fold and the production of singlet oxygen was increased 1.4-fold. AuNRs–Ce6 were taken up by the HeLa and KB cell lines more easily than free Ce6, enhancing the intracellular delivery of Ce6. The increased cellular amount of Ce6 leads to a 3-fold more efficient photodynamic killing of these two cell lines. This demonstrates the potential of this approach to improve photodynamic detection and therapy of cancers. [ABSTRACT FROM AUTHOR]

A new benzothiadiazole-based MOF {[Zn(BIBT)(oba)]·DMA}n (JXUST-3, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2oba = 4,4′-oxybisbenzoate) has been solvothermally synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy and TGA. The fluorescence studies suggest that JXUST-3 could simultaneously selectively sense trivalent metal ions including Al3+, Cr3+ and Fe3+ by a turn-off effect, and the detection limits are 0.055, 0.049 and 0.056 μM, respectively. Moreover, JXUST-3 exhibits relatively good thermal and chemical stabilities and reusability. The fluorescent test paper also displayed an obvious turn-off effect, indicating that JXUST-3 can be used as a potential multi-response fluorescent probe. The possible quenching mechanisms of JXUST-3 for Al3+ and Fe3+ were competitive energy absorption, and for Cr3+ ions, they were competitive energy absorption and weak interactions between Cr3+ and the framework. Therefore, JXUST-3 could be viewed as a transition metal MOF fluorescence sensor for Al3+, Cr3+ and Fe3+ by the turn-off effect, simultaneously. [ABSTRACT FROM AUTHOR]

A new and simple surface-enhanced Raman scattering (SERS) biosensor based on the tyramine signal amplification (TSA)-triggered formation of horseradish peroxidase (HRP) repeats on a gold sensing chip was designed for the highly sensitive detection of hydrogen peroxide (H 2 O 2 ). Initially, gold wafers were functionalized with HRP as sensing chips. Then, the HRP immobilized on the chips triggers the TSA reaction to transform the tyramine-HRP conjugate into a tyramine-HRP repeat array. With the aid of the target H 2 O 2 , the HRP repeats catalyze the oxidation of o -phenylenediamine (OPD) and produce an enzyme catalytic product with a different chemical structure, thus altering the fingerprint of the SERS spectra from that of OPD. H 2 O 2 can be quantitatively analyzed according to the change in SERS signal intensity. On the basis of the TSA strategy, the proposed method allows the detection of H 2 O 2 with a limit of detection (LOD) of 0.8 × 10 -8 M. The as-prepared SERS sensor can achieve high-sensitivity H 2 O 2 detection with a small amount of sample for each analysis. Therefore, this sensor exhibits significant potential for application in bioanalysis.

A novel nonanuclear nickel(ii) cluster identified as [Ni9(OH)6(CO3)2(ba)8(Hdmpz)6(DMF)2]·EtOH·2DMF (SD/Ni9a, Hba = benzoic acid, Hdmpz = 3,5-dimethyl-1H-pyrazole) is successfully constructed from mixed ligands. The single-crystal X-ray diffraction (SCXRD) structural analysis confirms the composition and reveals the "drum-like" inner core structure surrounded by ba- and DMF. Six Hdmpz ligands in their neutral form further sandwich the "drum" up and down, and is hydrogen bonded with two carbonate anions that are derived from the atmospheric CO2 with the help of Et3N. Electrospray ionization mass spectrometry (ESI-MS) reveals that the SD/Ni9a maintains an intact core in the solution with a slight exchange of outer ligands. Detailed collision-induced dissociation (CID) experiments reveal the collision energy (CE)-promoted ligand loss and exchange between ba- and Hdmpz. Furthermore, the magnetic study shows that there is no interaction between the Ni centers at room temperature, whereas the ferromagnetic coupling between the Ni centers is found with an S = 3 spin ground state of the cluster at low temperature. Moreover, the UV-vis spectrum and the photocurrent response measurements show its good optical properties with an indirect bandgap of about 2.35 eV and fast current response upon visible light irradiation.

Glutathione (GSH) in tumors consumes 1O2 and seriously inhibits the PDT effect. MnO2-coated porphyrin metal-organic frameworks are developed to realize the oxidation of GSH by MnO2 for enhanced PDT, activated MR imaging, and controllable release of DOX as magnetic resonance imaging guided drug-PDT dual-therapy.