Submission Date

7-24-2026

Document Type

Paper- Restricted to Campus Access

Department

Chemistry

Faculty Mentor

Mark Ellison

Comments

Presented during the 28th Annual Summer Fellows Symposium, July 24, 2026 at Ursinus College.

Project Description

Polydimethylsiloxane, or PDMS, is a silicone polymer commonly used in clinical settings due to its biocompatibility and chemical stability. However, a drawback to these characteristics is PDMS’s vulnerability to bacterial biofilm formation, leading to bacterial infections often nosocomial in nature. The purpose of the project is to investigate the employment of single-walled carbon nanotubes (SWCNTs) as a potential inhibitor of biofilm on PDMS, rather than antibiotics. Nanotubes have been found to exhibit antibacterial properties due to their hydrophobicity and can be easily functionalized to enhance this trait. Using Thiol-ene click chemistry, a rapid reaction performed under mild conditions in which a thiol attacks an alkene to create a new covalent bond, it is possible to permanently attach the SWCNTs to the PDMS surface. We functionalized SWCNTs with oleylamine, an alkene-containing molecule often used in nanotechnology to disrupt surface tension, and covalently bonded them to the thiol group of PDMS that had been functionalized with mercaptopropyltrimethoxysilane (MPTMS). Additionally, we functionalized SWCNTs with hexadecylamine, a saturated carbon chain, and evenly dispersed them on the PDMS surface. To test if these methods encourage biofilm inhibition, gram-negative bacteria Escherichia coli were deposited on the PDMS and incubated. Following this, the overall bacterial growth was measured by serial dilution and spot-plating. Additionally, surface-associated biofilm biomass was observed and measured with a fluorescent dye stain assay. Spectroscopic data from 1H NMR, ATR-FTIR, and Raman spectroscopy confirmed success in functionalization of SWCNTs, PDMS, and attachment of oleylamine-functionalized SWCNTs with MPTMS PDMS. Fluorescent stain assay indicates significantly less biofilm biomass on PDMS treated with hexadecylamine or oleylamine SWCNTs compared to plain, untreated PDMS disks. Furthermore, fluorescent control experiments with broth rather than E. coli culture demonstrate that little to no biofilm is adhering to the PDMS surface when nanotubes are present. CFU assay exhibits decreased bacterial growth on the PDMS treated with SWCNTs overall, showing that the SWCNTs are acting as antibacterial agents.

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