Properties of DNA-Based Organic Dyes Doped Membranes
A. Pawlicka, H. C. L. Oliveira, F. Kajzar and J. Kanicki
The deoxyribonucleic acid (DNA) sodium salt was reacted with hexadecyltrimethylammonium bromide (CTMA) to obtain DNA-CTMA organic-solvent soluble complex. The DNA-CTMA was then mixed with three organic dyes such as Nile Blue A (NB), Disperse Red 1 (DR1) and Disperse Orange 3 (DO3) resulting in colored membranes, that were characterized by UV-Vis, FTIR, X-ray, ionic conductivity and fluorescence analysis. The FTIR and UV-Vis spectra confirmed DNA-CTMA formation. The X-ray diffractograms show that the dye molecules accommodate between adjacent base pairs of DNA-CTMA chains promoting their separation. It is evidenced by increase of macromolecular chains spacing and the size of interplanar distance in comparison with DNA membranes. The ionic conductivities of DNA-CTMA-NB and DNA-CTMA-DR1 were found to be of 4×10-8 S/cm and 1.6×10-7 S/cm at 27 oC and 1.3×10-4 and 2.4×10-5 S/cm at 96°C, respectively. DNA-CTMA-DO3 ionic conductivities are of 6.7×10-8 S/cm at 26°C and 1.5×10-6 S/cm at 75°C. The photoluminescence spectra show that all the DNA-CTMA-dye membranes exhibit fluorescence with intensities in agreement with structural analysis, being respectively of 40, 54 and 180 for DNA-CTMA-Disperse Red 1, DNA-CTMA-Nile Blue A and DNA-CTMA-Disperse Orange 3, in the same order as the observed increase of crystallinity of the samples.
Keywords: DNA-CTMA-dye complexes, natural macromolecule derivative, conducting membranes, UV-VIS spectra, fluorescence