The work is dedicated to fabrication and study of SERS-active nanocomposites based on aluminum hydroxide with incorporated copper nanoparticles (CuNP; 10±2 nm). The initial CuNP and the final composite were characterized using SEM, EDX, STM, and absorbance spectroscopy in UV-visible range. The application of incorporation enabled to improve temporal stability of SERS-activity of the CuNP against oxidation to around 80 times compare to colloidal CuNP; the composite is SERS-active for more than 8 days. The value of Raman enhancement was found around 8×10<sup>6</sup> that is comparable with the values for silver and gold based SERS substrates. The applicability of the final composite for chemical analysis was demonstrated by SERS detection of some drugs, such as antitumor (methotrexate) and antibacterial drugs (lincomycin, sulfadimethoxine, ceftriaxone). The analytes were detected at concentrations which have to be detected at physiological conditions in urine (50‒100 μg/mL) after medical treatment.
Langmuir monolayers of quantum dots could be used as a platform for creation of planar fluorescent sensors that widely used in biology during immunochemistry analysis. Interesting feature is a creation of matrix with separated quantum dots one from each other. The process of Langmuir monolayers of quantum dots and fatty acid mixtures with different component ratios formation was studied. The method of compression isotherm was used for Langmuir monolayer formation process characterization, atomic force microscopy was used for transferred films characterization. Volume component ratios of 1:1, 1:2. 2:1, 1:5 and 5:1 of arachidic acid and quantum dots were studied. Was shown that increasing of the arachidic acid concentration in the solution cause to decreasing the maximal monolayer area, changing in monolayers liquid phase extensions and type. Also the monolayer compressibility and compression module are changes and achieves a peak value at components ratio of 1:1. At the indicated component ratio the formed Langmuir monolayer of quantum dots and arachidic acid mixture was transferred on the glass substrate and studied by atomic force microscopy.
Microcapsules with and without magnetite nanoparticles incorporated in the polyelectrolyte shell were prepared. The effect of external electric field on the nanocomposite polyelectrolyte microcapsules containing magnetite nanoparticles in the shell was studied in this work as a function of the electric field strength. Effect of electric fields on polyelectrolyte microcapsules and the control over integrity of polyelectrolyte microcapsules with and without inorganic nanoparticles by constant electric field has been investigated. Beads effect, aggregation and deformations of nanocomposite microcapsule shell in response to electric field were observed by confocal laser scanning microscopy (CLSM). Thus, a new approach for effect on the nanocomposite microcapsule, including opening microcapsule shell by an electric field, was demonstrated. These results can be used for creation of new systems for drug delivery systems with controllable release by external electric field.
The formation of a monolayer and its structure depend on many factors. One of the least studied factors is the influence of the electric field. In this regard, the purpose of this study is to investigate the influence of the direction and magnitude of the electric field on the properties of monolayer, formed on the surface of water. The experiments have revealed: the electric field exerts a significant influence on the formation of monolayers, in particular, during liquid phase formation. The second part of the isotherm (corresponding liquid phase) were significantly stretched. We explain the liquid phase extension by the fact of the charge increasing (and change pH) of the surface region. To confirm this assumption also we made computer modelling of process monolayer formation.
The process of formation of Langmuir monolayers of quantum dots at the different subphase temperatures was studied by means of compression isotherm, Brewster angle microscopy and transmission electron microscopy. The increasing of the maximum surface pressure from 32 to 44 mN/m takes place with decreasing the temperature from 34 to 11°C. This is due to a decrease in the rate of dissolution of surfactant molecules in water. The increasing of a filling degree of monolayer by the quantum dots and increasing of it uniformity in thickness takes place in this temperature range. The area of bilayer and multilayer film of quantum dots decreasing and the area of quantum dots monolayer is increasing. This change explained by the difference in the phase condition of oleic acid molecules, which stabilized quantum dots.