BSA-templated MnO(2) nanoparticles as both peroxidase and oxidase mimics

Inorganic nanomaterials that mimic enzymes are fascinating as they potentially have improved properties relative to native enzymes, such as greater resistance to extremes of pH and temperature and lower sensitivity to proteases. Although many artificial enzymes have been investigated, searching for highly-efficient and stable catalysts is still of great interest. In this paper, we first demonstrated that bovine serum albumin (BSA)-stabilized MnO(2) nanoparticles (NPs) exhibited highly peroxidase-, oxidase-, and catalase-like activities. The activities of the BSA-MnO(2) NPs were evaluated using the typical horseradish peroxidase (HRP) substrates o-phenylenediamine (OPD) and 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of either hydrogen peroxide or dissolved oxygen. These small-sized BSA-MnO(2) NPs with good dispersion, solubility and biocompatibility exhibited typical Michaelis-Menten kinetics and high affinity for H(2)O(2), OPD and TMB, indicating that BSA-MnO(2) NPs can be used as satisfactory enzyme mimics. Based on these findings, BSA-MnO(2) NPs were used as colorimetric immunoassay tags for the detection of goat anti-human IgG in place of HRP. The colorimetric immunoassay using BSA-MnO(2) NPs has the advantages of being fast, robust, inexpensive, easily prepared and with no HRP and H(2)O(2) being needed. These water-soluble BSA-MnO(2) NPs may have promising potential applications in biotechnology, bioassays, and biomedicine.     

The Active Ingredients of Jiang-Zhi-Ning: Study of the Nelumbo nucifera Alkaloids and Their Main Bioactive Metabolites

The object of this study was to identify the major active ingredients of the Chinese Traditional Medicine Jiang-Zhi-Ning (JZN) based on the high performance liquid chromatography (HPLC) profiles of plasma samples obtained from beagle dogs at different times after intragastric administration of JZN, crude JZN extracts, different extracted fractions, different subfractions of the active fraction and different isolated ingredients. 2-Hydroxy-1-methoxyaporphin (2H1M), an alkaloid from Nelumbo nucifera, one of the herbs that make up JZN, was identified as the constituent showing the major pharmacodynamic effect. The major metabolites of 2H1M were analyzed and identified as N-demethyl-2-hydroxy-1-methoxyaporphine-2-O-glycuronic acid, 2-hydroxy-1-methoxy-aporphine-2-O-glycuronic acid and 2-hydroxy-1-methoxy-aporphine-2-O-sulphate. This study provided a comprehensive insight into the active components of JZN.     

Microwave-accelerated derivatization prior to GC-MS determination of sex hormones

A new microwave-accelerated derivatization method was developed for rapid determination of 13 natural sex hormones in feeds. Sex hormones were isolated from the sample matrix by ultrasonic extraction, followed by solid-phase extraction, derivatized under microwave irradiation, and then analyzed directly by gas chromatography-mass spectrometry (GC-MS) in selective ion monitoring (SIM) mode. The key parameters affecting derivatization efficiency, including microwave irradiation time, microwave power, and reaction solvent were studied. Under microwave power of 360 W and microwave irradiation for 3 min, 13 natural sex hormones were simultaneously derivatized using heptafluorobutyric acid anhydride (HFBA) as derivatization reagent. This method was applied to the determination of 13 natural sex hormones in different feed samples, and the obtained results were compared with those obtained by the traditional thermal derivatization. The recoveries from 58.1 to 111% were obtained at sex hormone concentrations of 10-300 μg/kg with RSDs ≤12.0%. The results showed that the proposed method was fast, simple, efficient and can be applied to the determination of 13 natural sex hormones in different feed samples.     

The dynamics of a novel method coupling high-performance liquid chromatography with resonance Rayleigh scattering

The dynamics of a novel method coupling high‐performance liquid chromatography (HPLC) with resonance Rayleigh scattering (RRS) is presented in the paper. The method was employed in the detection of fluoroquinolones (FQs) of urine samples from healthy human beings, by forming ion‐association complexes between the components separated from HPLC and [Ce(OH)₃]⁺ as the molecular recognition probe. The RRS signal was measured at λ_ex=λ_em=365 nm. It was applied to detect three FQs and obtained satisfactory results. The RRS spectral characteristics of the analytes and the kinetics of flow rate, proportion of organic phase, reaction time and the aggregation level of ion‐association complexes were investigated, which provided a new basis for the development of the hyphenated techniques. It was established that the presence of HPLC‐RRS would open up a new field in the determination of analytes in the absence of UV or fluorescence.     

Quantifying the Tunable Conjugated Area of Graphene Oxide by Using Pyrene as a Fluorescent Probe

The determination of oxygenous groups, conjugated area ratio, and reduction efficiency of graphene oxide (GO) is a difficult task because of its heterogeneous structure. Herein, a novel approach is described for a detailed understanding of the surface chemistry of GO by using pyrene as a fluorescent probe through π–π stacking interactions.     

On-surface stereoconvergent synthesis,dimerization and hybridization of organocopper complexes

Despite the vital role of stereoconvergent synthesis in modern chemistry, the on-surface stereoconvergent synthesis of organometallic complexes involving transformation among several stereoisomers to one specific form has been few reported. By combination of high-resolution scanning tunneling microscopy(STM) imaging/manipulation and density functional theory(DFT) calculations, we have displayed the stereoconvergent synthesis of organocopper complexes via the Cu-alkene interaction and further dimerization into H-shaped motifs, in which two cis-forms and one trans-form are involved, and the specific adsorption configuration of one cis-form is revealed to be the key for such a synthesis. Furthermore, the generality of the dimerization of organocopper complexes has also been verified by codeposition of two similar molecular precursors, and the hybridized K-shaped motifs(made up of two kinds of organocopper complexes) have been successfully achieved. These findings may provide atomic-scale insights into the synthesis of specific stereoisomers in the fields of pharmaceuticals, biochemistry and organometallic chemistry.     

Large Scale Synthesis of Highly Stable Fluorescent Carbon Dots Using Silica Spheres as Carriers for Targeted Bioimaging of Cancer Cells

In this paper, fluorescent carbon dots (CDs) loaded on silica (SiO₂) spheres are synthesized by the one‐pot hydrothermal route, and then folic acids (FA) are covalently conjugated on the surface of SiO₂ spheres. The formed SiO₂@CDs‐FA composites can target specific tissues, e.g., cancer. The key of this method is the employment of (3‐aminopropyl)trimethoxysilane as bridge joint, which not only serves as surface passivation agents allowing the large scale synthesis of CDs with high quantum yield, but also enables SiO₂@CDs composites further covalent conjugation of FA. The resultant SiO₂@CDs composites have many advantages such as easy separation and purification, highly stable, well water‐soluble, and biocompatible. Moreover, the SiO₂@CDs‐FA could be used as fluorescent probes for biological imaging in vitro. The uptake of the SiO₂@CDs‐FA into HeLa cells is receptor‐mediated endocytosis, which is confirmed by a comparative study using FR‐negative 293T cells. Findings from this study suggest that the SiO₂@CDs‐FA composites could be used as a platform for cancer diagnosis studies in various biological systems.