Fluorospectrophotometric Determination of Trace Amounts of Nucleic Acid by Its Reaction with the Coordination Complex of Epigallocatechin Gallate with Cupric Ion

It was found that the fluorescence intensity of the coordination complex,epigallocatechin gallate with Cu(Ⅱ) ion EGCG-Cu(Ⅱ),was significantly enhanced through its interaction with nucleic acid in a buffer medium of pH 4.35-4.45,when measurements were made at wavelengths of 330 nm (λex) and 659 nm (λem).Linear relationship was obtained between the magnitude of enhanced fluorescence intensity and the concentration of nucleic acid.Based on these facts,a method for determination of nucleic acid was proposed.Linearity ranges for ctDNA,fsDNA and yRNA were found to be 0.3-10.0 mg·L-1,0.4-4.8 mg·L-1 and 0.4-30.0 mg·L-1,with detection limits (3S/K) of 0.22,0.15,0.14 mg·L-1 respectively under optimum condition.Tests for recovery were made by addition of standard solutions of ctDNA,fsDNA and yRNA at 3 different concentration levels,results of recovery obtained were in the range of 97.0%-104.4% with values of RSD′s (n=5)≤2.0%.