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Zhang Y.-G.,Lanzhou University | Shi Z.-H.,Lanzhou University | Yang L.-Z.,Lanzhou University | Tang X.-L.,Lanzhou University | And 3 more authors.
Inorganic Chemistry Communications | Year: 2014

A facile coumarin-based Schiff base sensor, 7-hydroxy-8-((2-hydroxy- phenylimino)methyl)-coumarin (H2L), has been designed and synthesized for selective detection of Al3 + in methanol-water (1:1, v/v). A fluorescence enhancement of 12-fold at 528 nm can be realized upon addition of 5.0 equiv. Al3 + with excitation at 421 nm. The mechanism of CN isomerization, coupled with photoinduced energy transfer, is proposed to explain the observed spectral response. Most importantly, this Al3 + sensor has good water-solubility and can be excited with light in the visible range. © 2013 Elsevier B.V.

Zhou X.,Lanzhou University | Li X.,Lanzhou University | Chen X.,Lanzhou University | Chen X.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province
Dyes and Pigments | Year: 2013

Orange G (OG) was used as a model compound to investigate the binding mechanism between azo dye and human serum albumin (HSA) using a variety of methods. These included nuclear magnetic resonance (NMR), saturation transfer difference (STD)-NMR, steady-state fluorescence, UV-vis absorption, circular dichroism (CD), Fourier transform infrared (FT-IR), three-dimensional fluorescence, time-resolved fluorescence spectroscopy, and molecular modeling method under simulated physiological conditions. The data of NMR and STD-NMR indicated that OG was indeed bound to HSA and located in the hydrophobic pocket of HSA. The fluorescence quenching data showed that the binding of OG and HSA quenched the intrinsic fluorescence of HSA, and the dynamic quenching constants were acquired. Thermodynamics analysis and molecular modeling studies suggested that GO bound to the site I on HSA molecule, and indicated the presence of hydrophobic forces. The alterations of protein conformational structures were further examined by synchronous fluorescence, UV-vis absorption, CD, FT-IR, three-dimensional fluorescence, and time-resolved fluorescence spectroscopy. © 2013 Elsevier B.V. All rights reserved.

Ma Y.,Lanzhou University | Zhang Z.,Lanzhou University | Ren C.,Lanzhou University | Liu G.,Lanzhou University | And 2 more authors.
Analyst | Year: 2012

In this paper, a novel and simple colorimetric method for the determination of reduced glutathione (GSH) based on Fe 3O 4 magnetic nanoparticles (MNPs) as peroxidase mimetics was developed. The Fe 3O 4 MNPs prepared via a coprecipitation method, which possess intrinsic peroxidase-like activity, were used as a catalyst in the color development reaction of a peroxidase substrate 2,2′-azino-bis(3- thylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) and H 2O 2. The existence of GSH can consume H 2O 2 and cause a color change of the reaction system which can be detected by the naked eye. Accordingly, the GSH can be detected by measuring the wastage of H 2O 2. A good linear relationship was obtained from 3.0 to 30.0 μM for GSH. Good recoveries ranging from 96.7 to 107% were obtained. Furthermore, it was used to detect GSH in A549 cells. © 2012 The Royal Society of Chemistry.

Su L.,Lanzhou University | Feng J.,Lanzhou University | Zhou X.,Lanzhou University | Ren C.,Lanzhou University | And 3 more authors.
Analytical Chemistry | Year: 2012

In this paper, we discovered that ZnFe2O4 magnetic nanoparticles (MNPs) possess intrinsic peroxidase-like activity. ZnFe 2O4 MNPs exhibit several advantages such as high catalytic efficiency, good stability, monodispersion, and rapid separation over other peroxidase nanomimetics and horseradish peroxidase (HRP). ZnFe2O 4 MNPs were used as a colorimetric biosensor for the detection of urine glucose. This method is simple, inexpensive, highly sensitive, and selective for glucose detection using glucose oxidase (GOx) and ZnFe 2O4 MNPs with a linear range from 1.25 × 10 -6 to 1.875 × 10-5 mol L-1 with a detection limit of 3.0 × 10-7 mol L-1. The color change observable by the naked eyes based on the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is the principle for the sensing of urine glucose level. © 2012 American Chemical Society.

Shen J.-M.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province | Shen J.-M.,Lanzhou University | Guan X.-M.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province | Liu X.-Y.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province | And 3 more authors.
Bioconjugate Chemistry | Year: 2012

We developed a novel chitosan-based luminescent/magnetic hybrid nanoparticles with folate-conjugated tetrapeptide composites (CLMNPs-tetrapeptide-FA) by conjugation in situ. First, chitosan, CdTe quantum dots (QDs), and superparamagnetic iron oxide were directly gelled into ternary hybrid nanogels. Subsequently, tetrapeptides (GFFG and LGPV) and folate were conjugated orderly into the hybrid nanoparticles. The morphology, composition, and properties of the as-prepared copolymers have also been characterized and determined using TEM, EDX, XRD, FTIR spectra, DLS, fluorescence spectroscopy, VSM, and fluorescence microscopy imaging studies. The size range of the end product CLMNPs-tetrapeptide-FA copolymers was from 150 to 190 nm under simulated physiological environment. In vivo, the experimental results of magnetic accumulation showed that the copolymers could be trapped in the tumor tissue under magnetic guidance. Under the present experimental conditions, the loading efficiencies of CPT were approximately 8.6 wt % for CLMNPs-GFFG-FA and 1.1 wt % for CLMNPs-LGPV-FA, respectively. The CPT cumulative release under dialysis condition mainly occurred for the first 28 h, and could reach 55% at pH 5.3 and 46% at pH 7.4 from CPT-loaded CLMNPs-GFFG-FA, and 69% at pH 5.3 and 57% at pH 7.4 from CPT-loaded CLMNPs-LGPV-FA within 28 h, respectively. The hemolysis percentages (<2%) and coagulation properties of blank and CPT-loaded copolymers were within the scope of safe values. Compared to free CPT, the CPT-loaded CLMNPs-tetrapeptide-FA copolymers showed specific targeting to A549 cells in vitro. More than 75% viability in L02 cells were seen in CLMNPs-GFFG-FA and CLMNPs-LGPV-FA copolymer concentration of 500 μg/mL, respectively. It was found that the two kinds of copolymers were transported into the A549 cells by a folate-receptor-mediated endocytosis mechanism. These results indicate that the multifunctional CLMNPs-tetrapeptide-FA copolymers possess a moderate CPT loading efficiency, low cytotoxicity, and favorable biocompatibility, and are promising candidates for tumor-targeted drug delivery. © 2012 American Chemical Society.

Zheng J.,Lanzhou University | Dong Y.,Lanzhou University | Wang W.,Lanzhou University | Ma Y.,Lanzhou University | And 3 more authors.
Nanoscale | Year: 2013

In this work, a facile approach was successfully developed for in situ catalyzing Au nanoparticles loaded on Fe3O4@SiO 2 magnetic nanospheres via Sn2+ linkage and reduction. After the Fe3O4@SiO2 MNPs were first prepared via a sol-gel process, only one step was needed to synthesize the Fe 3O4@SiO2-Au magnetic nanocomposites (Fe 3O4@SiO2-Au MNCs), so that both the synthesis step and the reaction cost were remarkably decreased. Significantly, the as-synthesized Fe3O4@SiO2-Au MNCs showed high performance in the catalytic reduction of 4-nitrophenol to 4-aminophenol and could be reused for several cycles with convenient magnetic separability. This approach provided a useful platform based on Fe3O 4@SiO2 MNPs for the fabrication of Au or other noble metal magnetic nanocatalysts, which would be very useful in various catalytic reductions. © 2013 The Royal Society of Chemistry.

Hui Y.,Lanzhou University | Li X.,Lanzhou University | Chen X.,Lanzhou University | Chen X.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province
Journal of Chromatography A | Year: 2011

The light-induced cis-trans isomerization of rhapontigenin (RHA) and its glucoside rhaponticin (RHA-Glc) were evaluated under ultraviolet (UV) light irradiation. A simple and rapid capillary electrophoresis method was developed for the kinetic study of four stilbenes (both cis and trans form of RHA and RHA-Glc). These analyses were achieved by using β-cyclodextrin (β-CD) modified capillary zone electrophoresis with diode array detector (CZE-DAD). The method provided reliable separations with a short analysis time of 3min. The purity of individual compound was checked by UV spectral comparisons with known standards, and further confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Furthermore, the UV absorbance and the molar absoptivity (e{open}) values were determined by UV-vis spectrophotometer to be 36824Lmol -1cm -1 at λ max 324.5nm for trans-RHA and 43894Lmol -1cm -1 at λ max 325nm for trans-RHA-Glc in methanol/water mixture solution (50%, v:v), respectively. CZE, UV-vis and NMR spectroscopy studies provided similar conclusions by considering the influence of irradiation time and the influence of irradiation wavelength. © 2011 Elsevier B.V.

Zhang H.,Lanzhou University | Chen Y.,Lanzhou University | Liang M.,Lanzhou University | Xu L.,Lanzhou University | And 4 more authors.
Analytical Chemistry | Year: 2014

Carbon quantum dots (C-Dots) have drawn extensive attention in recent years due to their stable physicochemical and photochemical properties. However, the development of nitrogen-doped carbon quantum dots (N-doped C-Dots) is still on its early stage. In this paper, a facile and high-output solid-phase synthesis approach was proposed for the fabrication of N-doped, highly fluorescent carbon quantum dots. The obtained N-doped C-Dots exhibited a strong blue emission with an absolute quantum yield (QY) of up to 31%, owing to fluorescence enhancement effect of introduced N atoms into carbon dots. The strong coordination of oxygen-rich groups on N-doped C-Dots to Fe3+ caused fluorescence quenching via nonradiative electron-transfer, leading to the quantitative detection of Fe3+. The probe exhibited a wide linear response concentration range (0.01-500 μM) to Fe3+ with a detection limit of 2.5 nM. Significantly, the N-doped C-Dots possess negligible cytotoxicity, excellent biocompatibility, and high photostability. All these features are favorable for label-free monitoring of Fe3+ in complex biological samples. It was then successfully applied for the fluorescence imaging of intracellular Fe3+. As an efficient chemosensor, the N-doped C-Dots hold great promise to broaden applications in biological systems. © 2014 American Chemical Society.

Zhou X.-M.,Lanzhou University | Lu W.-J.,Lanzhou University | Su L.,Lanzhou University | Shan Z.-J.,Lanzhou University | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2012

As endocrine-disrupting chemicals, a few frequently used phthalate plasticizers were banned or restricted for use as additives in food in some countries. The interaction mechanisms between three phthalate plasticizers with human serum albumin (HSA) were studied by fluorescence (quenching, synchronous, and three-dimensional), UV-vis absorption, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy, in combination with molecular modeling under simulative physiological conditions, respectively. The results obtained from fluorescence quenching data revealed that the plasticizers-HSA interaction altered the conformational strcture of HSA. Meanwhile, the alterations of HSA secondary structure in the presence of phthalate plasticizers were investigated. The binding distances for the plasticizers-HSA system were provided by the efficiency of fluorescence resonance energy transfer. Furthermore, the thermodynamic analysis implied that hydrophobic forces were the main interaction for the plasticizers-HSA system, which agreed well with the results from the molecular modeling study. © 2011 American Chemical Society.

Wang L.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province | Liu M.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province | Gao C.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province | Ma L.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province | Cui D.,Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province
Reactive and Functional Polymers | Year: 2010

In this work, a series of hydrogels were prepared by copolymerization of (2-dimethylamino) ethyl methacrylate (DMAEMA) and 3-acrylamidephenylboronic acid (AAPBA). The structure of the resultant hydrogels was studied by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The experimental results from swelling studies revealed that the hydrogels displayed definite glucose sensitivity under physiological conditions, as well as sharp changes in the mesh size of their network as a function of the pH and temperature of the swelling media. Bovine serum albumin (BSA) was selected as a model compound when examining protein release from hydrogels. The results suggested that the temperature, pH and glucose concentration of buffer solutions greatly influenced release profiles. © 2009 Elsevier Ltd. All rights reserved.

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