Exploiting the zwitterionic properties of lomefloxacin to tailor its delivery from functionalized MCM-41 silica

Mesoporous silica with ordered hexagonal pore array has attracted widespread interest for biomedicine, especially for drug delivery applications. Herein the zwitterionic nature of lomefloxacin was exploited to tailor the drug-carrier interactions. The influence of MCM-41 surface functionalization with different organic moieties (aminopropyl, propionitrile, propionic acid, mercaptopropyl and propylsulfonic acid) on the lomefloxacin release kinetics was reported. The antibiotic-loaded samples were prepared through incipient wetness impregnation method, having a drug content of 20 %wt. The functionalized MCM-41 supports and lomefloxacin-loaded materials were characterised by various techniques: FTIR spectroscopy, small- and wide-angle X-ray diffraction, nitrogen adsorption/desorption isotherms, as well as thermal analysis. The lomefloxacin release profiles were determined in saline phosphate buffer solution pH 7.4 and the experimental data were fitted with various mathematical models: three-parameter, Higuchi, and Weibull. The acidity of functional groups grafted on silica carrier influences the lomefloxacin delivery kinetics. From the viewpoint of obtaining controlled release formulations, the propionitrile functionalized MCM-41 carrier was the best, as it led to the lowest burst effect and highest amount of drug release during the sustained delivery stage. The developed lomefloxacin delivery systems showed similar bactericidal activity against Escherichia coli ATCC 8739 strain as the pure antibiotic.