Gold Nanoshell-Decorated
Silicone Surfaces for the Near-Infrared (NIR) Photothermal Destruction
of the Pathogenic Bacterium E. faecalis
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Abstract
Catheter-related infections (CRIs)
are associated with the formation of pathogenic biofilms on the surfaces
of silicone catheters, which are ubiquitous in medicine. These biofilms
provide protection against antimicrobial agents and facilitate the
development of bacterial resistance to antibiotics. The application
of photothermal agents on catheter surfaces is an innovative approach
to overcoming biofilm-generated CRIs. Gold nanoshells (AuNSs) represent
a promising photothermal tool, because they can be used to generate
heat upon exposure to near-infrared (NIR) radiation, are biologically
inert at physiological temperatures, and can be engineered for the
photothermal ablation of cells and tissue. In this study, AuNSs functionalized
with carboxylate-terminated organosulfur ligands were attached to
model catheter surfaces and tested for their effectiveness at killing
adhered Enterococcus faecalis (E. faecalis) bacteria. The morphology of the AuNSs
was characterized by scanning electron microscopy (SEM) and transmission
electron microscopy (TEM), while the elemental composition was characterized
by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron
spectroscopy (XPS). Furthermore, optical and photothermal properties
were acquired by ultraviolet–visible (UV-vis) spectroscopy
and thermographic imaging with an infrared camera, respectively. Bacterial
survival studies on AuNS-modified surfaces irradiated with and without
NIR light were evaluated using a colony-formation assay. These studies
demonstrated that AuNS-modified surfaces, when illuminated with NIR
light, can effectively kill E. faecalis on silicone surfaces