Mechanism of Addition Reaction of DNA with Acridine Orange and Its Application to the Determination of Micro-Amounts of DNA

The addition reaction of DNA with acridine orange was studied by spectrophotometry,and the conditions,i.e.the acidity,time of reaction and amount of acridine orange etc.for the reaction were optimized.As shown by the experimental results,the absorbance of acridine orange at 444 nm decreased with the increase of concentration of DNA added.In a B-R buffer solution of pH 6.5,linear relationship between the decrease in absorbance(ΔA=A0-A) and the concentration of DNA was found in the range within 8.0 mg·L-1(r=0.999 8).Based on these facts,a spectrophotometric method for determination of micro-amounts of DNA was proposed.In the determination of NDA in 3 simulated samples,values of RSD′s(n=5) and recoveries were found in the ranges of 1.4%-3.0% and 98.3%-104.0% respectively.Furthermore,a brief discussion on the mechanism of the addition reaction was given.