Biological implications of polydimethylsiloxane-based microfluidic cell culture

Abstract

Polydimethylsiloxane (PDMS) has become a staple of the microfluidics community by virtue of its simple fabrication process and material attributes, such as gas permeability, optical transparency, and flexibility. As microfluidic systems are put toward biological problems and increasingly utilized as cell culture platforms, the material properties of PDMS must be considered in a biological context. Two properties of PDMS were addressed in this study: the leaching of uncured oligomers from the polymer network into microchannel media, and the absorption of small, hydrophobic molecules (i.e. estrogen) from serum-containing media into the polymer bulk. Uncured PDMS oligomers were detectable via MALDI-MS in microchannel media both before and after Soxhlet extraction of PDMS devices in ethanol. Additionally, PDMS oligomers were identified in the plasma membranes of NMuMG cells cultured in PDMS microchannels for 24 hours. Cells cultured in extracted microchannels also contained a detectable amount of uncured PDMS. It was shown that MCF-7 cells seeded directly on PDMS inserts were responsive to hydrophilic prolactin but not hydrophobic estrogen, reflecting its specificity for absorbing small, hydrophobic molecules; and the presence of PDMS floating in wells significantly reduced cellular response to estrogen in a serum-dependent manner. Quantification of estrogen via ELISA revealed that microchannel estrogen partitioned rapidly into the surrounding PDMS to a ratio of approximately 9:1. Pretreatments such as blocking with serum or pre-absorbing estrogen for 24 hours did not affect estrogen loss from PDMS-based microchannels. These findings highlight the importance of careful consideration of culture system properties when determining an appropriate environment for biological experiments.

Manufacturing and wetting low-cost microfluidic cell separation devices

“…6 While these materials are popular, PS is not ideal for biological microfluidic devices 7 and may not satisfy clinical regulatory requirements; 8 PDMS has negative biological implications. 9 Additionally, devices manufactured with regulatoryapproved materials may be more rapidly approved for use. 8 The commercial development of clinical microfluidic devices requires low-cost materials from regulatory-approved suppliers.…”

Automatic sequential fluid handling with multilayer microfluidic sample isolated pumping

“…Besides, to use thermoplastics (PS, PC, PMMA, etc.) as the major materials would avoid some issues that are inevitable to the devices made of PDMS, such as leaching of uncured oligomers, 46 solution evaporation, 47 and small molecule absorption. 48 Also, these thermoplastic manufacturers are highly accessible in industries for high throughput manufacture, which makes this technology feasible for future commercialization.…”

Convenient surface functionalization of whole-Teflon chips with polydopamine coating

“…46 Generally, non-wetting substrates, such as PE and PTFE, are not favorable for cell adhesion and proliferation. 47 In our previous work, 8 cells adhered to the surface of PFA channels that were pretreated with concentrated sodium hydroxide overnight, which is time consuming with involvement of corrosive reagents.…”