Preparation of novel fluorescent DNA bio-dots and their application for biothiols and glutathione reductase activity detection.

A new class of fluorescent bio-dots have been successfully prepared by hydrothermal treatment of poly-cytosine DNA at low temperature down to 80 °C. The inter-molecule interaction of aromatic cytosine bases forms sp(2) carbon-like centers as the luminescence centers or chromophores. In the presence of Ag(+), the formation of C-Ag(+)-C base pairs results in the destroying of the luminescence centers and thus the fluorescence (FL) quenching of the bio-dots.

DNA-templated Ag nanoclusters as fluorescent probes for sensing and intracellular imaging of hydroxyl radicals.

We have developed a simple, rapid and label-free sensor for the essential biological OH radicals based on the fluorescence quenching of DNA-templated Ag nanoclusters (DNA-Ag NCs). The OH radicals generated from the Fenton reagent attack and cleave the DNA template, which disturbs the microenvironments around Ag NCs, resulting in spontaneous aggregation due to the lack of stabilization and further the quenching of the Ag NCs fluorescence. These changes in fluorescence intensity allow sensing of OH radicals with good sensitivity and selectivity under optimal conditions.

Using graphene quantum dots as photoluminescent probes for protein kinase sensing.

A simple and sensitive photoluminescence (PL) assay for the activity of a protein kinase based on the selective aggregation of phosphorylated peptide-graphene quantum dot (GQD) conjugates triggered by Zr(4+) ion coordination has been established. With more sophisticated design of the peptide substrate sequences, detecting other enzymes could also be possible. Under optimal conditions, a linear relationship between the decreased PL intensity of peptide-GQD conjugates and the concentration of casein kinase II (CK2) in the range from 0.

Graphene quantum dots combined with europium ions as photoluminescent probes for phosphate sensing.

The sense of it: A new type of rapid, sensitive, and specific photoluminescence (PL)-based assay has been proposed for the detection of phosphate (Pi) based on the competition of oxygen-donor atoms from Pi with those from the carboxylate groups on a graphene-quantum-dot (GQD) surface for Eu(3+) ions. The graphene-like structures combined with QD-like optical properties suggest the promising nature of the GQDs as versatile tools in the fields of analytical science and biotechnology.