A highly sensitive DNA-AIEgen-based ＂turn-on＂ fluorescence chemosensor for amplification analysis of Hg^2+ ions in real samples and living cells

Functional nucleic acids(FNAs)-based biosensors have shown great potential in heavy metal ions detection due to their low-cost and easy to operate merits. However, in most FNAs based fluorescence probes, the ingenious designs of double-labeled(fluorophore and quencher group) DNA sequence, not only bring the annoyance of organic synthesis, but also restrict its use as a robust biosensor in practical duties. In this paper, we design a simple AIEgens functional nucleic acids(AFNAs) probe which consists of only fluorogen but no quencher group. With the help of duplex-specific nuclease(DSN) enzyme based target recycling, high fluorescence signal and superior sensitivity towards Hg^(2+) are achieved. This robust assay allows for sensitive and selective detection of Hg^(2+) in real water samples and mapping of intracellular Hg^(2+), without double-labeling of oligonucleotide with a dye-quencher pair, nor the multiple assay steps.

B-GQDs@GSH as a Highly Selective and Sensitive Fluorescent Probe for the Detection of Fe^(3+) in Water Samples and Intracellular

Owing to the excellent stability,biocompatibility and photoluminescence property,graphene quantum dots(GQDs)are emerging as a kind of potential materials to be applied in a series of fields ranging from sensor to drug delivery.As the growing concern for human and environmental safety,selective detection of metal ions has been paid more and more attention.GQDs,as nanoparticles with superior optical properties,have been attracting growing attention in the field of metal ions detection.In this work,glutathione(GSH)functionalized boron doped graphene quantum dots(B-GQDs@GSH)were successfully synthesized with stable bright blue fluorescence and has been used for the detection of Fe^(3+).A good linear relationship between 1/(F_(0)-F)and 1/c with the concentration ranging from 0.70 to 53μmol/L was obtained with a detection limit of 5.5 nmol/L.The application of B-GQDs@GSH for Fe^(3+)detection in water samples was demonstrated and the quenching mechanism was further explored.Due to low cytotoxicity and favorable biocompatibility,B-GQDs@GSH were successfully applied for cell fluorescence imaging and intracellular determination of Fe^(3+).

A new insight into electrochemical detection of eugenol by hierarchical sheaf-like mesoporous NiCo2O4

NiCo2O4 nanosheets with sheaf-like nanostructure morphologies have been synthesized by a facile one-step hydrothermal reaction followed by annealing treatment. Impressively, the NiCo2O4 nanosheets exhibit rapid detection of eugenol. The linear range of detection is from 1-500μM, and the limit of detection is 5.4 μM. The NiCo2O4 modified electrode demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability （7% decrease in response over 30 days）. Based on this work, an electrochemical reaction mechanism for eugenol oxidation was proposed, and in addition, the NiCo2O4 modified electrode was successfully employed for the analysis of eugenol in medicative balm samples. Recovery values for eugenol in medicative balm samples were in the range 98.7%-105.5%.

Facile and large-scale synthesis of green-emitting carbon nanodots from aspartame and the applications for ferric ions sensing and cell imaging

A facile, economical and green strategy to prepare green-fluorescent nitrogen-doped carbon nanodots （N- CDs） with a quantum yield （QY） of approximately 31.91% has been built up, while aspartame was employed as the carbon-nitrogen source for the first time. The prepared N-CDs exhibited ultrahigh brightness, favorable strong photostability and negligible cytotoxicity. The outstanding optical properties are mainly derived from the their robost composition and steric distribution of the doped nitrogen atoms, which have been characterized detailedly. The obtained N-CDs showed highly selective and sensitive response toward ferric ions （Fe3＋） through a fluorescence static quenching process in a wide linear range of 0.005-60 μmol/L. The detection limit was as low as 1.43 nmol/L, allowing the analysis of Fe3＋ in a very simple method. The excitation-dependent luminescent behavior of the obtained N-CDs guaranteed the multicolor emissive property when they were used in cell imaging. And the application for intracellular Fe3＋ sensing further verified this novel N-CDs may open more opportunities in biosensor, bioimaging and biological assay.