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A fluorescent probe ( 1 ) for distinguishing amongst biothiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), is developed based on different cascade reactions. The key design feature of fluorescent probe 1 is the integration of two potential reaction groups for the thiol and amino groups of biothiols in one molecule. By reacting with the halogen atom and α, β-unsaturated malonitrile in probe 1 , Cys, Hcy and GSH can generate a total of three main products with distinct photophysical properties. Probe 1 shows a strong fluorescence turn-on response to Cys with blue–green emission by using an excitation wavelength of 390 nm. At an excitation wavelength of 500 nm, probe 1 responds to GSH over Cys and Hcy and emits strong orange fluorescence. The discrimination of biothiols can be demonstrated by cell imaging experiments, indicating that probe 1 can be a useful tool for the selective imaging of Cys and GSH in living cells. [ABSTRACT FROM AUTHOR]

Abstract: C60-carboxyfullerene, C60[C(COOH)2]2, has been proven to function as peroxidase mimetics that can catalyze the reaction of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue color reaction. Kinetic studies further indicate that C60[C(COOH)2]2 has an even higher affinity to TMB than that of the natural enzyme, horseradish peroxidase (HRP). C60[C(COOH)2]2/glucose oxidase (GO x )/TMB system provides a novel colorimetric sensor for glucose and shows good response toward glucose detection over a range of 1.0–40μM with a limit of detection 0.5μM (3σ/slope). Moreover, this sensitive and selective sensor can be successfully applied for the quantitative determination of glucose in human serum. The results indicate that it is a simple, cheap, convenient, highly selective, sensitive, and easy handling colorimetric assay. [Copyright &y& Elsevier]

Abstract: An ultrasensitive and selective detection of mercury (II) was investigated using a laser scanning confocal imaging-surface plasmon resonance system (LSCI-SPR). The detection limit was as low as 0.01ng/ml for Hg2+ ions in ultrapure and tap water based on a T-rich, single-stranded DNA (ssDNA)-modified gold film, which can be individually manipulated using specific T–Hg2+–T complex formation. The quenching intensity of the fluorescence images for rhodamine-labeled ssDNA fitted well with the changes in SPR. The changes varied with the Hg2+ ion concentration, which is unaffected by the presence of other metal ions. The coefficients obtained for ultrapure and tap water were 0.99902 and 0.99512, respectively, for the linear part over a range of 0.01–100ng/ml. The results show that the double-effect sensor has potential for practical applications with ultra sensitivity and selectivity, especially in online or real-time monitoring of Hg2+ ions pollution in tap water with the further improvement of portable LSCI-SPR instrument. [Copyright &y& Elsevier]