SUSTAINED ANTIBACTERIAL EFFECT OF LEVOFLOXACIN DRUG IN A POLYMER MATRIX BY HYBRIDIZATION WITH A LAYERED DOUBLE HYDROXIDE

Abstract

The immobilization of antimicrobial drugs can be used to expand the application of antibacterial properties to consumer products. The purpose of this study was to stabilize an antimicrobial agent, levofloxacin (LVX), for sustained antibacterial activity by immobilizing the drug molecules in a layered double hydroxide (LDH) and embedded in a polyurethane substrate. As-prepared MgAl-LDH was calcined at 400 degrees C and reconstructed with LVX for intercalation. The X-ray diffraction patterns and cross-sectional transmission electron microscopy images showed lattice expansion along the crystallographic c axis upon LVX intercalation, suggesting successful loading of the drug. Fourier-transform infrared spectra revealed that the structure of LVX was well preserved between LDH layers. Elemental analysis indicated that the loading capacity of LVX in the hybrid was 41.7%. Bacterial-colony forming inhibitory assay on Bacillus subtilis exhibited similar to 100% antibacterial activity of both LVX alone and LVX-LDH hybrid (LL). To determine sustainability of antibacterial activity by the hybrid, either LVX alone or LL hybrid was loaded in the polyurethane (PU) substrate for which antibacterial activity was evaluated before and after immersion in a phosphate-buffered saline for 3 days. The LVX-composited PU showed a dramatic decrease in antibacterial activity, down to 0% after buffer treatment; LL-composited PU still contained antibacterial activity (similar to 34% of colony suppression) after phosphate-buffered saline immersion.