  Bacterial biofilms can initiate chronic infections that become difficult to
eradicate. There is an unmet need for effective therapeutic strategies that
control and inhibit the growth of these biofilms. Herein, light sensitive
mesoporous silica nanoparticles (MSNs) with photothermal (PTT) and
antimicrobial combined capabilities have been developed. These nanosystems have
high therapeutic potential to affect the bacterial biofilm architecture and
subsequently inhibit its growth. Nucleation of gold nanorods followed by the
growth of a silica shell leads to a core@shell design (AuNR@MSN) with PTT
properties. Incorporation of nitrosothiol groups (-SNO) with a heat liable
linker, enables an enhanced nitric oxide release upon photothermal stimulation
with near infrared radiation. Further loading of an antimicrobial molecule such
as the levofloxacin (LEVO) antibiotic creates a unique nanoassembly with
potential therapeutic efficacy against Staphylococcus aureus bacterial
biofilms. A dispersion rate of the bacterial biofilm was evident when light
stimuli is applied because impregnation of the nitrosothiol functionalized
nanosystem with the antibiotic LEVO led to ca. 30% reduction but its
illumination with near infrared (NIR) irradiation showed a biofilm reduction of
ca. 90%, indicating that localized antimicrobial exposure and PTT improves the
therapeutic efficacy. These findings envision the conception of
near-infraredactivated nanoparticle carriers capable of combined therapy upon
NIR irradiation, which enables photothermal therapy, together with the release
of levofloxacin and nitric oxide to disrupt the integrity of bacterial biofilms
and achieve a potent antimicrobial therapy.
