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. However, with the addition of biothiols, Ag(+) prefers to react with biothiols to form the Ag(+)-S bond, hence a restoration of FL emission can be observed. Moreover, by employing the classic glutathione reductase (GR) catalyzed enzymatic reaction, this concept can be readily applied to the selective quantification of oxidized glutathione (GSSG) as well as the activity of GR with a very robust, simple, and rapid procedure. It is worth looking forward to design DNAs with a specific function to prepare fluorescent bio-dots for simple biological applications.