The Influence of Tetracycline Loading on the Surface Morphology and Biocompatibility of Films Made from P(3HB) Microspheres

Tetracycline, an antibiotic used against a broad range of Gram positive and Gram negative bacteria was encapsulated in microspheres made of poly(3-hydroxybutyric acid) P(3HB), a microbial biodegradable polymer isolated from Bacillus cereus SPV. The drug loaded microspheres were prepared using an oil emulsion technique and compressed uniaxially to produce films. Although the same fabrication conditions were used for preparing the drug loaded and unloaded microspheres, the presence of the drug changed the surface morphology and roughness of the films. The surface morphology of the drug loaded films appeared uneven and coarser and the roughness, with an average root mean square value of 5.89 mu m, was significantly higher than that of the unloaded film. The in vitro biocompatibility of the films was investigated using a human keratinocyte cell line (HaCaT) by comparing cell viability on the films to that on conventional tissue culture plastics. Both films appear to support cell growth but cell attachment and percentage cell viability were greater on the drug loaded films (32% of control) compared to the unloaded film (10% of control), possibly as a result of the non-uniform surface morphology and increased roughness of the drug loaded film. Thus, the above results illustrate that the drug loaded films, in addition to being a suitable matrix for drug delivery, represent an improved substrate for keratinocyte cell attachment.