Effect of gamma-ray irradiation on bacterial penetration power of chitosan/collagen blend membranes for wound dressing

The aim of this study is to investigate the effects of gamma-ray irradiation on the bacterial penetration power of chitosan/collagen blend membranes. For this study, commercially available chitosan, and collagen extracted from bovine tendon were made into solution using a modified acid-solution method. This solution is then used to prepare the chitosan, collagen and chitosan/collagen blend membranes via solution casting on a plastic plate. Each of the membranes are exposed to gamma-ray irradiation (0, 15 or 25 kGy), placed on an agar medium and immediately inoculated with Staphylococcus aureus. The bacterial penetration power of the irradiated specimens are determined by inspecting the growth of colony-forming units on the agar medium. Observations of the bacterial penetration power of each type of membrane are as follows: the collagen membranes displayed colony-forming units on the agar medium, the chitosan membranes had the colony-forming units encircling the membranes, while the chitosan/collagen membranes showed spots of colony-forming units. After exposure to the gamma-ray irradiation, a reduction in the colony-forming units was observed for each of the membranes. In addition, increasing the dose of the gamma-ray irradiation was shown to reduce the number of the colony-forming units on the agar medium for each membrane type. In conclusion, the collagen membranes were able to prevent penetration of S. areus, whereas, the membranes containing chitosan were penetrable to the bacteria. The number of the colony-forming units shown in the agar medium depended on the the gamma-ray doses.