BLEND EFFECT OF PCL ON ANTIMICROBIAL ACTIVITY OF DIFFERENT MOLECULAR WEIGHT CHITOSAN

Abstract

Background: Studies in the past have shown the inhibitory capability of chitosan on the growth of several microbial organisms such as E. coli, L. monocytogenes, S. typhimurium, P. aeruginosa, S. aureus. Polycaprolactone(PCL), which is synthetic polyester, makes for an interesting study in the preparation of polymer blends. Few other studies of PCL-chitosan blend towards oral pathogens such as S. mutans and A. actinomycetemcomitans have shown that adding PCL to chitosan can lower the antimicrobial activity of pure chitosan and results in the presence of microbes on the surface of the polymer film. Purpose of Study: The current study was undertaken to develop a new polymer material that comprises desirable properties from different polymers which are not possessed in individual polymer. Study Design: Experimental Method: Low molecular weight chitosan-PCL blends and medium molecular weight chitosan with PCL of different proportions such as 100:0, 80:20, 75:25, 60:40, 50:50, 20:80 were synthesized. The protocol for synthesizing polymer blends was carried out in the fume hood. S.auerus was used for screening antibacterial activity of chitosan-PCL blend. The zone of inhibition was measured in diameter (mm). The number of colonies was counted by comparing the test plates with control and data was recorded. Result: Analysis of crystallinity has shown that when the concentration of chitosan was high, there were not many pits and holes present on the film. However, when the concentration of chitosan decreased, we could see more holes and pits there. In low molecular weight chitosan-PCL blend, based on S.aureus colony count, antimicrobial activity was low for 100% chitosan but the antimicrobial activity rose rapidly in 80:20 chitosan-PCL blends, showing that the addition of PCL increased antimicrobial activity. Low molecular weight Chitosan-PCL blends of 75:25, 60:40 and 50:50 proportions showed 100% inhibition.For medium molecular weight chitosan-PCL blends, antimicrobial activity on S. aureus based on colony count, number of colonies increased in 80:20 chitosan-PCL ratio and at the ratio of 75:25 and 60:40, no S.aureus colonies were found, depicting 100% inhibition. However, the addition of PCL beyond this point did not show antimicrobial activity. Conclusion: The addition of PCL to medium molecular weight chitosan enhanced the antimicrobial effectiveness on S.aureus until particular ratio of PCL, after that the effect was decreased when the concentration of PCL in the blends increased. This result was in contrast to the antimicrobial testing of low molecular weight chitosan-PCL blends. Low molecular weight chitosan with PCL blends showed better inhibition when the concentration of PCL was higher.