Biomimetic nanopillars to combat biomaterial associated infections (BAIs)
The demand for polymeric medical devices is expected to increase rapidly in the next few decades. However, the risk of bacterial infection of medical devices remains a major issue. Due to the problem of biomaterial-associated infections (BAIs) and growing numbers of antimicrobial resistant bacteria, it is crucial to develop novel materials that can combat BAIs (Moriarty, 2012). One such option is to develop a scalable nanofabrication technique that can exploit the antibacterial properties shown by nanostructured surfaces found in nature.
A template method (anodisation and hot embossing) is used to design and fabricate three different polymeric nanopillars on polyethylene terephthalate (PET) substrate that differs in terms of sharpness and density of the nanopillars. Contact angle and surface energy of the test surfaces was measured using KRÜSS Drop Shape Analyzer (DSA100). Two Gram-negative bacteria (E. coli and K. Pneumoniae) and one Gram-positive bacteria (S. aureus) were tested against the nanostructured surfaces for three hours. The membrane susceptibility and vitality were determined using Live/Dead and Bactiter Glo assays, respectively. Colloidal probe AFM was performed to investigate the nanotribological properties of the nanopillared surfaces. AFM, SEM, FIB-SEM and fluorescence microscope images were used to understand the nanopillar-bacteria interaction. 3D model of the bacteria adhere to the nanostructured surface was reconstructed using Avizo software (Fig 1). Finally, trypsin assay was used to understand the importance of surface proteins during bacterial adhesion to nanostructured surfaces.
Taken together, these data provide important information that could be exploited to inform the fabrication of antimicrobial surfaces for polymeric medical devices and provide an experimental basis from which a new theoretical model of bacterial attachment to nanostructured surfaces may be developed.
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|Extended Abstract||SEM vs 3D model||Figure 1. 3D reconstruction of E. coli adhered to the sharp and dense (SDN) surface. (A) SEM image of 2 E. coli cells on SDN surface. (B) 3D reconstruction of the 95 orthoslices from FIB milling data using Avizo 9.4 software.||1 MB||Download|