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

Polydimethylsiloxane (PDMS), often assumed to be biocompatible, is widely used in microfluidic devices and biomedical research. Here, we systematically assess the organismal effects of PDMS network components and their leachates using Caenorhabditis elegans as a whole-animal model. We demonstrate that uncrosslinked vinyl-terminated PDMS (v-PDMS) chains, which comprise the majority of a PDMS network and are known to diffuse into aqueous environments, exhibit acute, environmentally-dependent toxicity. Low-molecular-weight v-PDMS (6 kDa) caused mild lethality in nutrient-rich S-Medium but significantly higher mortality in minimal S-Buffer, showing that media composition strongly influences toxic effects. Adding cholesterol, calcium, or magnesium notably reduced v-PDMS-induced lethality, whereas trace metals increased it. Using a DAF-16::GFP reporter strain, we show that cholesterol influences organismal stress responses to v-PDMS exposures. Progeny from starved parents showed full resistance to v-PDMS, suggesting transgenerational stress memory plays a role in reducing PDMS toxicity. We also find that linear siloxanes cause modest but significant lethality, whereas cyclic siloxanes do not. The PDMS crosslinker TDSS, however, provides partial protection when present with v-PDMS, revealing diverse biological effects among PDMS network precursors. Overall, these results show that PDMS-derived components are not universally harmless and that susceptibility depends greatly on environmental conditions, sterol levels, and physiological history. Our findings emphasize the importance of carefully evaluating PDMS formulations for biomedical use and offer a framework for assessing polymer leachate toxicity in living organisms.