Bacterial infections and associated biofilms growing on the surface of biomedical devices, particularly catheters, represent a global problem that poses considerable financial and health consequences.  Therefore, it is critical to develop novel approaches to limit the proliferation of these pathogenic microorganisms on catheter surfaces.  Photothermal ablation of bacterial cells is an intriguing method for preventing microbial colonization on catheter surfaces, which are comprised in most cases of polydimethylsiloxane (PDMS).  Critical to this technique is the use of photothermal agents that absorb light and convert it to heat to kill harmful catheter-related bacteria such as <i>Enterococcus faecalis (E. faecalis)</i>.  Gold nanoparticles (AuNPs) with various morphologies (e.g., rod, spherical, star, and shell) are attractive candidates for photothermal destruction of pathogenic bacteria because of their biological inertness, chemical stability, unique photophysical properties, and efficient heat generation from adsorbed light due to their strong surface plasmon resonance (SPR).  In this study, two model catheter PDMS films modified with 80 and 150 nm gold nanostars (AuNSts) were prepared for evaluating their capacity for the photothermal destruction of harmful bacteria.  To overcome the challenges of embedding metal nanoparticles in polymer matrices, such as rapid diffusion and loss of the nanoparticles from the polymer matrix, the AuNSts were functionalized with our recently developed oligomeric dimethylsiloxane (ODMS)-terminated organosulfur ligands before encapsulating them in the PDMS films.  The ODMS-functionalized AuNSts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and UV-Vis-NIR spectroscopy.  Preliminary studies of the colonization and photothermal ablation of <i>E. faecalis</i> bacteria on the AuNSt-embedded PDMS films will be discussed.

Gold nanostar-modified polydimethylsiloxane films for photothermal ablation of bacteria

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ACS Fall 2022

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