Assessing PDMS Biocompatibility in Microfluidic Applications: Toxicity and Survival Outcomes in C. elegans

Area of Science:

• Biomaterials Science
• Toxicology
• Developmental Biology

Background:

• Polydimethylsiloxane (PDMS) is widely used in microfluidics and biomedical research, often assumed to be biocompatible.
• PDMS network components, particularly uncrosslinked vinyl-terminated PDMS (v-PDMS) chains, can leach into aqueous environments.

Purpose of the Study:

• To systematically assess the organismal effects of PDMS network components and their leachates.
• To investigate the influence of environmental factors and physiological history on PDMS toxicity.

Main Methods:

• Utilized *Caenorhabditis elegans* as a whole-animal model to evaluate PDMS toxicity.
• Assessed the impact of varying media composition, specific ions (cholesterol, calcium, magnesium, trace metals), and parental starvation on v-PDMS toxicity.
• Employed a DAF-16::GFP reporter strain to examine stress responses and analyzed the effects of linear and cyclic siloxanes and the PDMS crosslinker TDSS.

Main Results:

• Uncrosslinked v-PDMS chains exhibit acute, environmentally-dependent toxicity, with higher mortality in minimal buffer compared to nutrient-rich medium.
• Cholesterol, calcium, and magnesium reduced v-PDMS lethality, while trace metals increased it; cholesterol modulated stress responses.
• Transgenerational stress memory (from starved parents) conferred full resistance to v-PDMS, and linear siloxanes caused toxicity, unlike cyclic siloxanes.

Conclusions:

• PDMS-derived components are not universally benign, and their toxicity is significantly influenced by environmental conditions, sterol levels, and organismal physiological history.
• The findings underscore the need for careful evaluation of PDMS formulations for biomedical applications.
• A framework is proposed for assessing polymer leachate toxicity in living organisms.