Chitosan microspheres were prepared by ionically cross-linked chitosan with amphoteric
N
O
-carboxymethyl chitosan(CM-chitosan).CM-chitosan with a isoelectric point (IEP)2.86 was synthesized by chemical reacting chitosan with monochloroacetic acid
and the chemical structure was analyzed by IR and
13
C NMR.By adding CM-chitosan into chitosan solution
microspheres were formed instantaneously
and the structure of microspheres was characterized by IR and microscopy.The observation of optical microscopy
scanning electron microscopy and transmission electron microscopy showed that the ratio of chitosan to CM-chitosan had more influence on morphology and size of the microspheres than ultrasonic power
indicating that the charge action between this two polyelectrolytes were the mechanism of microsphere formation.This mechanism was also confirmed by measurement the change of absorbance and conductivity with pHvalue of chitosan/CM-chitosan solution
the result also showed that the pH range for microsphere formation is IEP