Molecular spectroscopy study of the reaction of nucleic acids with brilliant cresol blue

The interaction of brilliant cresol blue (BCB) with nucleic acids in aqueou s solution has been studied by spectrophotometry and Rayleigh light scatter ing (RLS) spectroscopy. Under suitable conditions, the RLS spectra of BCB c hanged significantly due to the presence of nucleic acids. RLS intensity of BCB at 364 nm is greatly enhanced with the addition of nucleic acids, and a new RLS peak is observed at 552 nm. This peak is about half the intensity of that at 364 nm. The results of this study show that BCB interacts with DNA possibly due to the cooperative effect of electrostatic attraction, int ercalation, coordination and hydrophobic effect. Under optimum conditions, the increase of RLS at 364 nm of a BCB solution is proportional to the conc entration of nucleic acids added. This result is the basis for a new RLS me thod for determination of nucleic acids. The linear range of ctDNA, fsDNA a nd yRNA is 0.12-4.70, 0.11-4.64 and 0.43-7.07 mu g ml(-1), respectively. (C ) 2000 Elsevier Science B.V. All rights reserved.