Properties and transformations of methylene blue nanoparticles.

The formation, properties and transformation of methylene blue (MB) nanoparticles in benzene - dimethyl sulfoxide (DMSO) and toluene - DMSO mixtures were investigated using absorption, fluorescence and resonance Rayleigh scattering spectra. The acquired spectral data, taken together, enable distinguishing between the three regions on the scale of DMSO mole fractions in the solvent mixture. The first region simultaneously contains MB nanoparticles (npMB), ion pairs (MB+, Cl-) and a small amount of MB+, the second region consists of ion pairs and MB+, while and the third region involves only MB+.