Assembly and Characterization of Ternary SV−DNA−TMPyP Complex Langmuir−Blodgett Films

Abstract

Ternary complex Langmuir−Blodgett (LB) films containing 1,1‘-dioctadecyl-4,4‘-bipyridinium (SV), deoxyribonucleic acid (DNA), and 5,10,15,20-tetrakis(4-N-methylpyridyl)porphine tetra(p-toluenesulfonate) (TMPyP) were assembled in two ways. One was assembled by depositing the complex monolayer of SV/DNA/TMPyP, which was in situ formed through the adsorption of aqueous subphase containing DNA and TMPyP onto the spreading SV monolayer (type I). Another was obtained by reacting the preformed SV/DNA LB film with TMPyP in aqueous solution (type II). A series of methods, such as surface pressure−area isotherms, atomic force microscopy (AFM), polarized UV−vis spectra, circular dichroism (CD), X-ray diffraction (XRD), and fluorescence lifetime measurements, were used to characterize these ternary LB films. The isotherm measurement indicated that stable complex monolayers could be formed at the air−water interface through the adsorption between SV and DNA or DNA/TMPyP. AFM showed different morphologies of type I and...