engleski

Synthesis and characterization of multilayer nanocapsules made of weak polyelectrolytes

Polyelectrolytes are macromolecules (e.g. polymers) with dissociating functional groups which can carry positive or negative charge in solution. By alternating adsorption of positively and negatively charged polyelectrolytes on a substrate surface, thin films called polyelectrolyte multilayers are formed. In the case of adsorption on colloidal particles followed by the dissolution of the template, it is possible to prepare hollow polyelectrolyte capsules of colloidal dimensions. Due to a large number of available polymeric compounds and easily tunable multilayer properties, these systems find their application in various fields such as biomedicine and catalysis. In this study, hollow nanocapsules made of weak polyelectrolytes, poly(allylamine) (PAH) and poly(acrylic acid) (PAA) were successfully designed, synthesized and characterized. The formation of the polyelectrolyte multilayer on fully biocompatible hydroxyapatite (HA) nanoparticles was monitored by measuring the electrophoretic mobility of particles. After the optimization of the substrate decomposition conditions, hollow polyelectrolyte capsules were prepared by dissolution of the template in the presence of HCl. Further characterization was performed using infrared spectroscopy, energy dispersion X-ray analysis, dynamic light scattering, scanning electron microscopy and atomic force microscopy. With these methods, the chemical composition, structure, size and morphology of obtained nanocapsules were determined. It was found that the capsules are of a rather narrow size distribution ranging from 100 to 250 nm with a flexible capsule wall being only a few tens of nanometers thick. Moreover, the dispersions of capsules were stable for at least 40 days. This extreme stability of nanocapsules could be attributed to their small dimensions, low mass and high surface charge.

Polyelectrolyte ; Polyelectrolyte multilayer ; Nanocapsules ; Drug delivery

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