Quaternized chitosan particles prepared by self-assembly of amphiphilic chitosan

Abstract

Quaternized chitosan particles were prepared by self assembly of amphiphilic chitosan having phthaloyl (Ph), hexyl (He) or dodecyl (Do) groups as hydrophobic entity and poly(ethylene glycol)methyl ether (mPEG) or N-[(2-hydroxyl-3-trimethylammonium)]propyl (HTAP) groups as hydrophilic entity that were immobilized on chitosan via chemical reactions of amino and/or hydroxyl groups. Unlike the chitosan particles having HTAP moieties, a subsequent heterogeneous methylation was necessary to introduce positively charged quaternary ammonium groups to the particles having mPEG moieties. Chemical structures of all amphiphilic chitosan derivatives were verified by 1H NMR and FT-IR spectroscopy. The relative degree of substitution (%DS) of each functionality can be varied as a function of mole equivalent of reagent used in each step of reaction. All quaternized amphiphilic chitosan exhibited a critical micelle concentration in a range of 7-17 µg/mL. According to SEM analysis, the particles have spherical morphology and a size range of 100–300 nm which is independent on %DS variation. And only the particles having He and Do as hydrophobic entities and HTAP as hydrophilic entities having degree of quaternization more than 50% exhibited high positive charges.