Destruction of shells and release of a protein from microcapsules consisting of non-biodegradable polyelectrolytes

ABSTRACT Using fluorescent spectroscopy, we examined degradation of PAH/PSS microcapsule shells and release of a protein from them. The processes were controlled by various concentrations of NaCl and (NH4)2SO4 and levels of pH: 5 and 7.4. We found that a high concentration of sodium chloride (2 М) causes essential dissociation of PAH from the upper shell layer and explained this by the layer loosening under the ionic strength. Using the optical spectroscopy, we determined amount of a microcapsule polyelectrolyte (PAH) and found that less than 20% of it can be released into 2М NaCl solution, and only 2% can be released into the water medium. Increase in solution pH up to 7.4 causes peeling of PAH too, however, temperature increase up to 37°С decreases this effect due to the structuring and compacting of the shell demonstrated by electron-microscopic studies. And finally we found that a scarce release of an encapsulated protein from the microcapsules does not depend on the presence of salts in the medium, their concentrations and a medium pH. GRAPHICAL ABSTRACT