  Tuberculosis remains today a major public health issue with a total of 9
million new cases and 2 million deaths annually. The lack of an effective
vaccine and the increasing emergence of new strains of Mycobacterium
tuberculosis (Mtb) highly resistant to antibiotics, anticipate a complicated
scenario in the near future. The use of nanoparticles features as an
alternative to antibiotics in tackling this problem due to their potential
effectiveness in resistant bacterial strains. In this context, silver
nanoparticles have demonstrated high bactericidal efficacy, although their use
is limited by their relatively high toxicity, which calls for the design of
nanocarriers that allow silver based nanoparticles to be safely delivered to
the target cells or tissues. In this work mesoporous silica nanoparticles are
used as carriers of silver based nanoparticles as antimycobacterial agent
against Mtb. Two different synthetic approaches have been used to afford, on
the one hand, a 2D hexagonal mesoporous silica nanosystem which contains silver
bromide nanoparticles distributed all through the silica network and, on the
other hand, a core@shell nanosystem with metallic silver nanoparticles as core
and mesoporous silica shell in a radial mesoporous rearrangement. Both
materials have demonstrated good antimycobacterial capacity in in vitro test
using Mtb, being lower the minimum inhibitory concentration for the nanosystem
which contains silver bromide. Therefore, the interaction of this material with
the mycobacterial cell has been studied by cryo-electron microscopy,
establishing a direct connection between the antimycobactericidal effect
observed and the damage induced in the cell envelope.
