Synthesis of polymeric nanocapsules for levofloxacin delivery against Staphylococcus aureus

Rodrigo Manuel Nogueira Nobre

Key information

Authors:

Rodrigo Manuel Nogueira Nobre (Rodrigo Manuel Nogueira Nobre)

Supervisors:

José Paulo Sequeira Farinha (José Paulo Sequeira Farinha); Ana Francisca de Campos Simão Bettencourt

Published in

12/05/2018

Abstract

In recent years, total bone replacement surgeries are becoming more frequent and problems associated to this procedure such as osteomyelitis are getting more common. Currently, therapeutical approaches consist on the administration of large doses of antibiotics for a long period of time. This is often ineffective due to the low vascularization of the prosthesis and the formation of bacterial biofilms. Particularly, infections associated to Staphylococcus aureus are specially challenging. The aim of the present work was to develop novel poly (methyl methacrylate) (PMMA) nanocapsules containing levofloxacin. Nanocapsules were synthesized through nanoprecipitation by solvent evaporation. Two types of nanocapsules were prepared with two different PMMA molecular weight (120000 and 350000 g/mol). The synthesized nanocapsules were characterized by NMR, UV-Visible spectroscopy, fluorescence microscopy and in vitro drug release assays. Blank nanocapsules were also prepared to serve as controls. To evaluate the antimicrobial activity of these novel drug delivery systems towards Staphylococcus aureus (ATCC®25923), two tests were conducted. The Kirby-Bauer diffusion and the biofilm inhibition on the surface of a PMMA bone cement. With both types of levofloxacin-loaded PMMA nanocapsules, 120000 and 350000 g/mol, the agar-diffusion results showed an inhibition zone diameter of 35 ± 1 mm and 37 ± 2 mm, respectively. Also, the growth of S. aureus biofilms was not verified with both types of nanocapsules proving the in vitro antimicrobial efficiency of the newly developed drug delivery systems.