Preparation, characterization and functional evaluation of chitosan-based films with zein coatings produced by cold plasma.

Chitosan-based films with zein coatings were prepared in order to modify the drug release properties. The adhesion of zein layers to the films was ensured via a cold plasma treatment. Using ciprofloxacin hydrochloride as model, the effect of cold plasma on the functional properties and structures was evaluated. The results suggest that the encapsulation efficiency, chemical composition and crystal type of ciprofloxacin hydrochloride in chitosan/drug films were not altered by cold plasma treatment, while the wettability and surface free energy displayed a notable increase. After being coated with zein, the chitosan interacted with the zein through hydrogen bonding and electrostatic interactions. The burst release phenomenon of the chitosan/drug films was prevented by the zein coating. Furthermore, the plasma treatment provided the coated film with a slower release rate within 24 h, from 72.8% to 49.3%. The enhanced coating thickness and the more compact interface structure were responsible for this improvement.