Enhanced fluorescence of the terbium-gadolinium-nucleic acids system and the determination of nucleic acids

It is first found that the fluorescence of Tb-nucleic acids (fish sperm DNA (fsDNA) and yeast RNA (yRNA)) can be increased by Sc3+, Y3+ La3+, Gd3+ and Lu3+, among which Gd3+ and Lu3+ have the greatest enhancement. This is a n ew co-luminescence system. This system is studied in detail and is applied to determine nucleic acids. The experiments indicated that under the optimu m conditions, a linear relationship was obtained between the fluorescence i ntensity (I-f) and the concentration of nucleic acids. The linear ranges ar e 1.0 x 10(-8)-1.2 x 10(-4) g/ml for DNA and 2.5 x 10(-8)-8.5 x 10(-4) g/ml for RNA. The detection Limits (signal:noise = 3) for DNA and RNA were 4.3 x 10(-9) and 6.4 x 10(-9) g/ml, respectively. The mechanism of the co-lumin escence effect is also discussed. (C) 2000 Elsevier Science B.V. All rights reserved.