Abstract
A dual-fluorescence “turn off–on” biosensor, which consists of quantum dots (GSH-CdTe QDs) whose fluorescence was quenched by safranine T (ST) via an electron transfer process, had been developed for herring sperm DNA (hsDNA) detection. Initially, in the “turn off” stage, the strong fluorescence of GSH-CdTe QDs could be effectively quenched by ST owing to the occurrence of the electron transfer from the photoexcited GSH-CdTe QDs to ST. And then, the high affinity of DNA to ST enabled the ST attached to the surface of GSH-CdTe QDs, to become embedded into hsDNA double helix structure to form stable complex and moved away from the QDs. Therefore, the recognition of hsDNA could be realized via the fluorescence restoration of the QDs–ST based biosensor, namely of the fluorescence “turn on” procedure. This designed biosensor exhibited good sensitivity and selectivity, for the reason that the detection limit for DNA reached 10.8ng/mL, meanwhile, neither biologically relevant metal ions, common organic compounds, nor the amino acid had any significant interference in the detection mode. Hence, this simple, fast, sensitive, and selective biosensor owned perfect analysis applications in biochemical DNA monitoring.
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