  This work aims to provide an effective and novel solution for the treatment
of infection by using nanovehicles loaded with antibiotics capable of
penetrating the bacterial wall, thus increasing the antimicrobial
effectiveness. These nanosystems, named "nanoantibiotics", are composed of
mesoporous silica nanoparticles (MSNs), which act as nanocarriers of an
antimicrobial agent (levofloxacin, LEVO) localized inside the mesopores. To
provide the nanosystem of bacterial membrane interaction capability, a
polycationic dendrimer, concretely the poly(propyleneimine) dendrimer of third
generation (G3), was covalently grafted to the external surface of the
LEVO-loaded MSNs. After physicochemical characterization of this
nanoantibiotic, the release kinetics of LEVO and the antimicrobial efficacy of
each released dosage were evaluated. Besides, internalization studies of the
MSNs functionalized with the G3 dendrimer were carried out, showing a high
penetrability throughout Gram-negative bacterial membranes. This work evidences
that the synergistic combination of polycationic dendrimers as bacterial
membrane permeabilization agents with LEVO-loaded MSNs triggers an efficient
antimicrobial effect on Gram-negative bacterial biofilm. These positive results
open up very promising expectations for their potential application in new
infection therapies.
