Bacteriostatic activity of fluoroquinolone coatings on polyethylene films

Abstract

Low-density polyethylene films were surface modified through a three-step procedure to impart antibacterial property. Plasma treatment was followed by allylamine grafting to generate active functionalities on the surface. Three potent antibiotics including norfloxacin, ciprofloxacin and ofloxacin were then separately coated onto the surfaces. Each step of surface modification was well characterized in terms of chemical composition and bioactivity. It was found that the chemical structure of the antibiotic was highly determining in extent of antibiotic immobilization as well as in final biological performance of the modified substrates. An excellent activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial growth was observed for norfloxacin-coated substrate which corresponded to the highest amount of the antibiotic immobilized. However, almost no activity was seen for ofloxacin-coated surface. This was attributed to the ease of the antibiotic coating on the allylamine-grafted substrate where the lowest degree of coating was found for ofloxacin due to its unfavorable chemical structure. Gram-negative bacterial strain was found more vulnerable than Gram-positive strain which was explained on the basis of their different cell wall composition. The chemical structure of the antibiotic was found to be determining in amount of the material coated and also in level of the exhibited antibacterial activity.