Electrostatic Complexation Of Chitosan/pectin/Arabic Gum And Effects Of Ions On Properties And Mechanical Function Of PEC Film

In acidic condition, positively charged chitosan and negatively charged pectin, gum Arabic form chitosan/pectin/gum Arabic polyelectrolyte complexes(PEC). Based on the method of compound coacervation, effects of characteristics of chitosan and pectin, ratio, solution pH and polymer concentration on turbidity and ?-potential of solution were investigated and the affecting mechanisms, electrostatic complexation between chitosan and pectin, gum Arabic were elaborated by combining the microstructure of complex. Influence of ion species and concentration on chitosan/pectin/gum Arabic PEC solution and the properties and mechanical properties of film were explored in this paper. Fourthermore, the release of BSA from PEC film with various ions were compared. The results were as follows:1. Chitosan with medium molecular weight(15 W) react more easily with pectin to form large complexes, while the deacetylation degree of chitosan had small effect on turbidity of complexation solution; high methoxyl pectin could form compact complexes with chitosan; with the addition level of pectin increasing, the microstructure of complexes changed from loose and sparse to more compacter, and the turbidity of solution showed 4 phases; the ?-potential of complexation particles became 0 at pectin addition level of with 82 %(w/w), but the turbidity of solution didn’t reach the maximum; when the solution pH was between 3.0 and 4.0, chitosan and pectin were easiest to interact with each other to form complexes with a even, dense structure and the solution had higher turbidity; complexes formed by chitosan and pectin with various concentrations showed significant different structure because of the effects of polymer concentration on stretch of molecular chain and polyelectrolyte complexation.2. chitosan with molecular weight of 15 W reacted more easily with gum arabic; the degree of chitosan deacetylation exhibited significant effect on complexation when there was excess gum Arabic in solution, and chitosan with lower degree of deacetylation could form larger PEC; Addition of gum arabic affected the microstructure of PEC significantly and the turbidity of solution showed 4 phases with addition level of gum arabic; when pH was between 3.0 and 4.0, solution showed highest turbidity and the microstructure of PEC changed with pH changing; microstructure of PEC and turbidity of solution changed with the concentration of polymers changing. The aforementioned conditions affected density of charge, extensibility and flexibility of molecular chains, so microstructure of PEC and turbidity of solution changed as a result.3. Diffirent adding order of pectin and gum Arabic into chitosan solution led to different turbidity of complex solution and microstructure of PEC. Higher turbidity of complex solution and more compact microstructure of PEC could be obtained when pectin was added after chitosan mixed thouroughly with gum Arabic.4. The turbidity of PEC solution increased then decreased as the concentration of ions in complexes increased, and the consentrations of various ions at which the maximum turbidity of PEC solution was obtained were different; the swelling degrees of chitosan/pectin/gum Arabic PEC films with different ions in water were as follows: FeCl3>CaCl2>Fe2(SO4)3>NaCl>MgSO4>Na2SO4; The influence of ion variousity and concentration on surface contact angle of PEC film was consistent with the results of swelling degree.5. PEC films with NaCl of 30 mM, CaCl2 of 40 mM, FeCl3 of 40mM、Na2SO4 of 10 mM, MgSO4 of 10 mM, and Fe2(SO4)3 of 10 mM had the maximum tensile strength, but the elongation at break was generally lower, and showed a little brittle. FT-IR analysis indicated that ions had no effect on the ieteraction between chitosan, pectin and gum Arabic. SEM to observe the surface morphology of PEC films found that the surface of PEC films that had higher swelling degree was much rougher, while the surface of PEC films that had lower swelling degree were much smoother.6. The embedding rate and drug-loading rate of PEC films with various ions were as follows: FeCl3 > CaCl2>Na2SO4; In single simulated environment, chitosan/pectin/gum Arabic complexes showed distinctive drug release progress; in continuous simulated oral environment, the drug release progress of PEC films was as follows: release degree was lower in simulated gastric environment, but relatively higher in the simulated intestinal environment, and in simulated intestinal environment with pectin enzyme, the release rate could reach 100%. The BSA accumulative release rate of PEC film crosslinking with CaCl2 was lower in simulated gastric and intestinal environment and relatively higher in simulated colon environment,which indicated that it could be used as drug carrier for colon delivery.