Fluorescence Enhancement of Lanthenum-Curcumin-Cetyltrimethylammonium Bromide-Nucleic Acid System for Determination of Nucleic Acids

Curcumin (CU) is an extremely rare natural diketones antioxidant used as anti-inflammatory and anticarcinogenic agents. A new fluorimetric method for the determination of nucleic acid was developed based on the enhanced fluorescence system La3+-curcumin(CU)-cetyltrimethylammonium bromide (CTMAB)- nucleic acid. In this system, in hexamethylene-tetramine-HCl buffer (pH = 5.80), 1.00 x 10(-3) mol/L CTMAB, 2.00 X 10(-5) mol/L CU, 1.40 x 10(-4) mol/L La3+, nucleic acids can enhanced the fluorescence intensity of La3+-CU-CTMAB and the enhanced intensities are quantitatively in proportion to the concentrations of nucleic acids in the range of 7.00 x 10(-4)-10.00 mg/L for fsDNA, 4.00 x 10(-4)-10.00 mg/L for ctDNA and 7.00 x 10(-4)-10.00 mg/L for yRNA, with corresponding detection limits (S/N=3) of 0.17, 0.02 14 mu g/L. L-A comparison between the proposed method and other analysis methods for nucleic acids was made. The results show that this method has a relatively wide linear range and high sensitivity. Study on reaction mechanism reveals that the phosphate group of nucleic acid can bind with CU through electrostatic attraction and meanwhile CU can interact with nucleic acid in the mode of groove binding. Such binding force changes the hydrophobic microenvironment of fluorescence probe, decrease the nonradioactive energy loses of the system and enhance its fluorescence intensity.