Langmuir Aggregation of Nile Blue (NB) on DNA and Application

The study on the interaction of a stain with nucleic acids makes to understand the function of the genetic macromolecules and analyze the transmission of the genetic information. The combination of both the Langmuir adsorptionand the spectral correction techniquewill provide a very helpful experimental strategy for study of chromophore or its metallic complex’s adsorption in surfactant solution. This method is named Micro Phase Adsorption- Spectral Correction (MPASC) was described. It provides a very helpful experimental strategy for study of aggregation of a stain on biomacromolecules. Commonly, nucleic acid molecule contains complex spatial structure. The helix, winding and folds lead of manyholes, gulliesand grooves.Many polar bonds are nearto each other to form many microelectrostatic fields. They will selectively attract charged organic compounds in only monolayer till kinetic equilibrium. So the property constants of the aggregate may be determined such as equilibrium constant, binding ratio, etc. The adsorption of NB on DNA has been investigated at pH=10.38 and it obeyedthe langmuir monolayer adsorption. Results show that the adsorption ratio of NB to DNA(-P) is 3∶1, adsorption constant 3.33×105and real absorptivity 4.81×103L/molcm at 660 nm. By varying the operation condition, we observed that the adsorption ratio of NB to DNA decreased with increase of ionic strength and temperature and addition of ionic surfactant e.g. CTAB and SDBS. This indicates the interaction is an adsorption reaction not a complexation. This interaction has been applied to the quantitative determination of DNA in samples. In the presence of EDTA, many ions or compounds such as C2O42-, protein, acetone, alkali earths, Mn(II), Cu(II), Fe(II), Zn(II), Pb(II), Ni(II), Co(II), Cd(II) and Hg(II) did not interfered the direct determination of DNA. For analysis of samples, the recovery of DNA is between 95.6% and 108% and relative standard deviation 2.8%.