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Highly soluble fluorescent pyrene derivative with substantially improved fluorescence intensity in aqueous buffer was obtained viaPEGylation strategy. The highly soluble PEGylated pyrene (PEO-Py) non-covalently adsorbed onto the surface of gold nanoparticles (Au NPs) to form dyads with quenched fluorescence due to highly efficient energy transfer between PEO-Py and Au NPs. The PEO-Py/Au NPs dyads were used for the sensitive turn-on fluorescent detection of biothiols. The fluorescence of PEO-Py was restored by the addition of cysteine (Cys), indicating that Cys can modulate the energy transfer between PEO-Py and Au NPs. This phenomenon then allowed for the sensitive detection of Cys with a limit of detection (LOD) of 11.4 nM. The linear range of determination of Cys was from 1.25 × 10−8to 2.25 × 10−7M. None of the other amino acids found in proteins showed obvious interference with the determination. It was important to note that the detection sensitivity of the PEO-Py/Au NPs system was more than 5-fold improved compared with the Py/Au NPs system. In addition, other biothiol molecules, such as glutathione, could also be detected by this sensor system. The method was also successfully applied to the determination of the total content of aminothiols in human plasma. Therefore an easily prepared, inexpensive, high solubility fluorescent probe has been realized and is also expected to detect other biological analytes of interest. [ABSTRACT FROM AUTHOR]

Highly soluble fluorescent pyrene derivative with substantially improved fluorescence intensity in aqueous buffer was obtained viaPEGylation strategy. The highly soluble PEGylated pyrene (PEO-Py) non-covalently adsorbed onto the surface of gold nanoparticles (Au NPs) to form dyads with quenched fluorescence due to highly efficient energy transfer between PEO-Py and Au NPs. The PEO-Py/Au NPs dyads were used for the sensitive turn-on fluorescent detection of biothiols. The fluorescence of PEO-Py was restored by the addition of cysteine (Cys), indicating that Cys can modulate the energy transfer between PEO-Py and Au NPs. This phenomenon then allowed for the sensitive detection of Cys with a limit of detection (LOD) of 11.4 nM. The linear range of determination of Cys was from 1.25 × 10−8to 2.25 × 10−7M. None of the other amino acids found in proteins showed obvious interference with the determination. It was important to note that the detection sensitivity of the PEO-Py/Au NPs system was more than 5-fold improved compared with the Py/Au NPs system. In addition, other biothiol molecules, such as glutathione, could also be detected by this sensor system. The method was also successfully applied to the determination of the total content of aminothiols in human plasma. Therefore an easily prepared, inexpensive, high solubility fluorescent probe has been realized and is also expected to detect other biological analytes of interest. [ABSTRACT FROM AUTHOR]

An alkaline phosphatase activity detection system was constructed based on the different quenching effect of the enzyme substrate and product on the β-CD-functionalized CdTe QDs. [ABSTRACT FROM AUTHOR]

Herein, BSA–tetraphenylethene derivative conjugates with aggregation-induced emission (AIE) properties were constructed and used as fluorescent probes for label-free detection of protease and α1-antitrypsin. Conjugated AIE probes were formed based on the electrostatic induced assembly between an ammonium cation of quaternized tetraphenylethene salt and carboxyl anion groups of BSA. While water soluble quaternized tetraphenylethene salt showed very low fluorescence in its well-dispersed state, obvious enhancement in the fluorescence of the aggregated tetraphenylethene derivative on the BSA templates was achieved due to the abnormal aggregation-induced emission properties of tetraphenylethene. These BSA–tetraphenylethene derivative conjugates enabled label-free detection of protease. In the presence of trypsin, the BSA templates were enzymatically hydrolyzed and the conjugates decomposed. Therefore the quaternized tetraphenylethene molecules became increasingly isolated from each other. Accordingly, the aggregation to dispersing state change of tetraphenylethene derivative resulted in an obvious decrease in the fluorescence of the conjugates probes and enabled the sensitive and selective detection of trypsin. Furthermore, upon addition of α1-antitrypsin, the enzymatic activity of trypsin was inhibited and the fluorescence was consequently preserved. Sensitive detection of α1-antitrypsin was thus realised. The protein–tetraphenylethene derivative conjugates with aggregation-induced emission properties therefore show great promise for the monitoring of biological processes and cancer diagnostics with simplicity, high sensitivity, and rapid response. [ABSTRACT FROM AUTHOR]