Effect of ionic strength on DNA–dye interactions of Victoria blue B and methylene green using UV–visible spectroscopy

Victoria blue and methylene green dyes have both been extensively studied due to their numerous applications, including their ability to bind to DNA. Dyes are very important in everyday life with applications in textile, cosmetics, food and pharmaceutical industries. It has been found that some of them adversely affect human health causing severe abnormalities. Among these abnormalities, cancer is of great concern due to its fatal and almost non-recoverable nature. In this work we have studied the binding of two dyes namely Victoria blue B (VBB) and Methylene green (MG) with double stranded DNA (Salmon sperm). The interactions were studied in the presence of different concentrations of buffer solutions at a constant pH. The selected dyes showed interactions with double-stranded DNA through intercalation and electrostatic modes. Upon increasing ionic strength of the buffer the binding constant (K b ) value for MG was decreased whereas increased for VBB, which conclude that, at higher ionic strength (0.5 M) the DNA–MG interactions is lower and DNA–VVB interactions is maximum. The carcinogenicity of a given dye is indicated from its binding constants in the current study. Based on the recorded K b values of the selected dyes it was concluded that proper disposing and precautions should be taken while utilizing/dealing these dyes in order to minimize/avoid their impact on environment and human health.