[Spectroscopic studies of interaction of brilliant cresyl blue and DNA]

The interaction of dye brilliant cresyl blue (BCB), which features a phenoxonium group, with hydroxypropyl-beta-cyclodextrinl and DNA in aqueous solution was studied by spectroscopic methods. The experimental results indicate that BCB can be included into the hydrophobic cavity of HP-beta-CD to form an inclusion, a complex with a stability constant of 1.98 x 10(3) L x mol(-1). At low DNA concentrations, BCB can be bound to DNA to form a 1:1 association complex with the binding constant of 4.3 x 10(4) mol x L(-1), and the major binding model of BCB to DNA is "electrostatic binding". However, the major binding model changes to "intercalative binding" at high DNA concentrations. In addition, the interactions of BCB-(HP-beta-CD) inclusion complex and DNA have been investigated. The results suggest that BCB displayed a high affinity for DNA and the inclusion complex decomposed when it was bound to DNA.