Langmuir monolayers and Langmuir-Blodgett films of functional amphiphilic amines and their interfacial complexes with colloid nanoparticles and polyelectrolytes

Development and study of novel biomimetic and biocompatible nano-engineered functional nanofilm materials are currently important from fundamental and applied viewpoints [1]. Such nanomaterials can serve as model systems for insight into the basic structural-functional interconnections at the nano-scale in biological membranes and are useful for bio-medical applications including controlled drug delivery. We present results of a study of novel nanofilm structures (Langmuir monolayers and Langmuir-Blodgett films) formed by functional amphiphilic amines and their interfacial complexes with colloid nanoparticles and polyelectrolytes including DNA. It was found that stearoylspermine molecules form stable Langmuir monolayer on an aqueous subphase surface. The stearylspermine Langmuir monolayer compression isotherm changes caused by interactions of the monolayer with aqueous subphase components (colloid ligand-free magnetite nanoparticles and DNA molecules) have been studied. The observed characteristic changes in Langmuir monolayer compression isotherms indicated to the binding of nanoparticles and polyanions with cationic stearoylspermine monolayer. Monolayer LB films of interfacial polycomplexes formed by stearylspermine and magnetite nanoparticles or DNA molecules were deposited onto the mica substrate surface and the structure of obtained films was investigated using AFM technique. The Langmuir monolayers and deposited LB films of the other type of functional amine-containing compounds which are pH-sensitive synthetic lipids have been also studied. In our work the pH-sensitive lipid trans-4,5,didodecyloxycarbonyl- trans-2-morpholinocyclohexanol was synthesized and studied. We have found the substantial changes of the Langmuir monolayer compression isotherm shape of that lipid caused by the change in aqueous subphase pH value from 7.5 to 5. Those changes can be the result of pH- induced conformational changes in the pH-sensitive lipid molecule. Corresponding monolayer LB films were deposited on mica substrate and studied using AFM technique. The various pH-dependent structural features including surface micelles were observed in the LB films deposited at various pH subphase values. The investigated functional amine-containing compounds are promising candidates for many potential applications including formation of liposomal vesicles for encapsulation and controlled release, DNA and drug delivery, formation of functional coatings on various substrate surfaces, etc.