Antimicrobial Properties and Release Profile of Ampicillin from Electrospun Poly(εepsilon;-caprolactone) Nanofiber Yarns

Poly(εepsilon;-caprolactone) (PCL) electrospun fibers containing ampicillin sodium salt have been produced and twisted into nanofiber yarns. The fiber diameters and crystallinity, the in vitro antimicrobial properties of the yarns, and the in vitro release of ampicillin from yarns containing various ampicillin concentrations are studied. Decreased fiber diameters and reduced diameter variation are observed with the addition of ampicillin salt into the polymer solution. The results from the zone of inhibition test of the yarns against both gram-positive Staphylococcus aureus and gram-negative Klebsiella pneumoniae indicate that the released ampicillin retains its effectiveness after the production processes, therefore the as-spun yarns are antimicrobial active. A burst release of ampicillin from the yarns has been observed in the first hour, and the release is almost completed in 96 hours. The burst release is believed to be due to the low compatibility of ampicillin with PCL, the accumulation of ampicillin on fiber surface and the small fiber diameters. An empirical release model is developed to describe the release profile. The results indicate that the electrospun nanofibers yarns will have a great potential to be used for biomaterials, such as surgical sutures, to decrease the surgical site infection rate.