Enhancing antimicrobial activity of β-lactam antibiotic via functionalized mesoporous carbon-based delivery platforms

Abstract

Bacterial immunity to antibiotics is currently increasing as a result of inadequate drug use and the generation of antimicrobial resistance. Developing new antibiotics is challenging, hence suitable carriers are sought to enhance activity of already known drugs. The ordered mesoporous carbons modified with urea, thiourea, and cetyltrimethylammonium bromide (CTAB), presented in this study, show great potential as carrier platforms for tebipenem pivoxil - a broad-spectrum orally-administered β-lactam antibiotic. The functional groups generated on the surface of carbon materials contributed to the reduction of their negative surface charge, which turned into positive under low pH conditions. At the same time, they led to a decrease in the hexagonal structure ordering of the carbon samples and a deterioration of the textural parameters. The effect of the amount of modifier used on the ability of carbon materials to release the selected antibiotic was investigated. The drug release process was carried out in two different environments (neutral and strongly acidic). It has been shown that the presence of functional groups on the surface of carbon carriers determines the amount of antibiotic liberated, especially at pH 7.0. The antimicrobial activity of the tebipenem pivoxil-loaded into the carbon carriers was assessed on a group of gram-positive and gram-negative bacteria. The highest decrease in the minimal inhibitory concentration value for the CTAB-modified systems was demonstrated, indicating a better antimicrobial efficiency against pathogenic strains coupled with an improvement in tebipenem pivoxil solubility. Small and negatively charged worm-like particles of the surfactant-functionalized carbon carrier are characterized by better dispersion in the receptor fluid resulting in faster and more effective diffusion of the antibiotic molecules from their outer surface. Ordered mesoporous carbons in addition to increased antibiotic dissolution rate, have no impact on drug permeability in the gastrointestinal tract in the in vitro model.