The refractive index (RI) of polymer nanocomposite of poly(vinyl alcohol) films with ${\mathrm{TiO}}_2$ nanoparticle inclusions with low concentration up to 1.2 wt. % was investigated. Accurate refractometric measurements, by a specially designed laser microrefractometer, were performed at wavelengths 532 and 632.8 nm. The influence of ${\mathrm{TiO}}_2$ concentration on the RI dispersion curves was predicted based on the well-known Sellmeier model. The theoretical analysis, in a small filling factor approximation, was performed, and a relation between the effective RI of the nanocomposite and weight concentrations of the ${\mathrm{TiO}}_2$ nanofiller was derived. The experimental values were approximated by two different functions (linear and a quadratic polynom). The polynomial approximation yields better result, where $R^2=0.90$.

This research aims to investigate the properties of nano- and micro-sized casein hydrogels crosslinked by sodium tripolyphosphate as drug delivery systems. Benzydamine hydrochloride was chosen as a model hydrophilic drug. The gels were synthesized by varying different parameters: casein concentration, casein/crosslinking ratio, and addition of ethanol as a co-solvent. The electrostatic attractive interactions between the casein and the sodium tripolyphosphate were confirmed by FTIR spectroscopy. The particle sizes was determined by dynamic light scattering and varied in the range between several hundred nanometers and several microns. The yield of the gelation process was high for all investigated samples and varied between 55.3% and 78.3%. The encapsulation efficiency of the particles was strongly influenced by the casein concentration and casein/crosslinker ratio and its values were between 4.6% and 22.4%. The release study confirmed that casein particles are useful as benzydamine carriers and ensured prolonged release over 72 h.

Polyelectrolyte multilayers (PEMs) deposited on porous composite polylactic acid/poly(ε-caprolactone) (PDLA/PEC) substrates were studied. The substrates were previously charged in a corona discharge. Time dependences of the normalized surface potential for positively and negatively charged electrets were investigated. The morphology of the obtained porous substrates was examined by means of scanning electron microscopy (SEM). The chitosan and the casein polyelectrolytes were deposited on the substrates using the layer-by-layer (LbL) technique. The drug loading efficiency and the release kinetics were determined spectrophotometrically.

In the present paper the effect of the substrate type and the corona polarity were investigated. Various biopolymer substrates (poly lactic acid (PLA), PLA with chitosan and lyophilized PLA) were prepared. These substrates were charged in a positive and in a negative corona and time dependences of the normalized surface potential were studied. After that multilayer films were formed by alternative dipping the substrates into chitosan and xanthan polyelectrolyte solutions. For this purpose 0.1% chitosan solution and 0.05% xanthan solution in acetate buffers with pH 4.5 and ionic strength 0.1 mol/l were used. The films’ morphology was investigated by FTIR and SEM methods. А comparative analysis of the experimental results was presented and the most appropriate substrate type for the irreversible binding of the chitosan/ xanthan polyelectrolytes was determined.