A FRET ratiometric fluorescent sensor was developed for detecting H(2)S in aqueous media and serum, as well as inside live cells. For this sensor, carbon dots serve as the energy donor and also the anchoring site for the probe. This sensor is highly selective and sensitive with a detection limit of 10 nM which is the lowest among fluorescent H(2)S sensors.

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The cultivation of single crystals from solution is usually a time-consuming trial-and-error game. Here, we report a general strategy for rapidly cultivating single crystals from melt microdroplets within tens of...

Overprediction is a major limitation of current crystal structure prediction (CSP) methods. It is difficult to determine whether computer-predicted polymorphic structures are artefacts of the calculation model or are polymorphs that have not yet been found. Here, we reported the well-known vitamin nicotinamide (NIC) to be a highly polymorphic compound with nine solved single-crystal structures determined by performing melt crystallization. A CSP calculation successfully identifies all six Z′ = 1 and 2 experimental structures, five of which defy 66 years of attempts at being explored using solution crystallization. Our study demonstrates that when combined with our strategy for cultivating single crystals from melt microdroplets, melt crystallization has turned out to be an efficient tool for exploring polymorphic landscapes to better understand polymorphic crystallization and to more effectively test the accuracy of theoretical predictions, especially in regions inaccessible by solution crystallization.

Aberrant expression of histone deacetylases (HDACs) is related to various types of cancer and is associated with increased proliferation of tumor cells. Hence, the detection of HDAC activities is of great significance for medical sciences as well as biological diagnostics. Herein, we report a hyperbranched polyester-based one-step fluorescent assay for HDAC. This assay system consists of two water-soluble components: the hyperbranched polyester coupled with the acetylated lysine groups (H40-Lys(Ac)) and the negatively charged TPE derivative bearing two sulfonic acid groups (TPE-2SO3(-)). HDAC triggers the deacetylation of H40-Lys(Ac), thereby turning the electroneutral polymer into the positively charged one. Consequently, complexation occurs between the positively charged polymer and the negatively charged TPE-2SO3(-), thereby leading to the formation of nanoaggregates due to electrostatic interaction. Eventually, the fluorescence enhancement as a result of AIE effect is achieved. This assay system is operable in aqueous media with very low detection limit of 25 ng/mL. The system is capable of detecting HDAC in such biological fluid as serum, and this strategy may provide a new and effective approach for enzyme assay.