Synthesis and characterization of chitosan-modified polymethyl methacrylate latex particles

Stable chitosan-modified polymethyl methacrylate (PMMA) latex particles wer e prepared by using 2,2'-azobis(2-amidinopropane) dihydrochloride (V-50) as the cationic initiator. The polymerization rate (R-p) is controlled by the V-50 concentration ([V-50]) and R-p is less sensitive to the chitosan conc entration ([C]) used in the synthesis work. The reaction system follows Smi th-Ewart Case III kinetics due to the relatively large particles produced. The zeta potential data show that the isoelectric point (pI) of the latex p articles is 10.7. The amounts of V-50 (CV-50) and chitosan (C-c) ultimately incorporated into the particles correlate reasonably well with [V-50] and [C], respectively. At pH 7, the quantity of the negatively charged bovine s erum albumin (BSA, pI = 4.8) adsorbed on the positively charged chitosan-fr ee particles (&) via the electrostatic interaction increases with increasin g CV-50. However, & is relatively insensitive to changes in C-c. This resul t implies that only the outermost region of the hairy chitosan-modified par ticles is available for adsorption of the relatively large protein species. Colloidal stability shows a significant influence on the BSA adsorption pr ocess. (C) 1999 John Wiley & Sons, Inc.