Disregarded Free Chains Affect Bacterial Adhesion on Cross-Linked Polydimethylsiloxane Surfaces

Area of Science:

• Biomaterials Science
• Microbiology
• Surface Chemistry

Background:

• Chemically cross-linked polydimethylsiloxanes (CPDMS) are studied for bacteria-material interactions.
• Uncross-linked free polydimethylsiloxane (PDMS) chains in CPDMS are often overlooked.
• These free chains can influence biofilm formation on elastomer surfaces.

Purpose of the Study:

• To investigate the impact of free chains in CPDMS on bacterial adhesion.
• To compare bacterial adhesion on flat and textured Sharklet CPDMS surfaces with and without free chains.

Main Methods:

• Comparative characterization of bacterial adhesion.
• Solvent extraction to remove free chains from CPDMS surfaces.
• Quantification of bacterial colony-forming units (CFUs) at initial adhesion stages.

Main Results:

• Removing free chains from both flat and textured CPDMS surfaces dramatically increased bacterial adhesion (2-3 orders of magnitude).
• This effect was observed for both Gram-negative and Gram-positive bacteria within 2 hours.
• Unextracted surfaces showed significantly lower bacterial adhesion compared to extracted surfaces.

Conclusions:

• The presence of free PDMS chains significantly inhibits initial bacterial adhesion.
• Solvent extraction of free chains is essential for accurate studies of bacteria-silicone elastomer interactions.
• Understanding free chain influence is critical for controlling biofilm formation on PDMS materials.