Lung on a Chip Development from Off-Stoichiometry Thiol–Ene Polymer

Abstract

Current in vitro models have significant limitations for new respiratory disease research and rapid drug repurposing. Lung on a chip (LOAC) technology offers a potential solution to these problems. However, these devices typically are fabricated from polydimethylsiloxane (PDMS), which has small hydrophobic molecule absorption, which hinders the application of this technology in drug repurposing for respiratory diseases. Off-stoichiometry thiol–ene (OSTE) is a promising alternative material class to PDMS. Therefore, this study aimed to test OSTE as an alternative material for LOAC prototype development and compare it to PDMS. We tested OSTE material for light transmission, small molecule absorption, inhibition of enzymatic reactions, membrane particle, and fluorescent dye absorption. Next, we microfabricated LOAC devices from PDMS and OSTE, functionalized with human umbilical vein endothelial cell (HUVEC) and A549 cell lines, and analyzed them with immunofluorescence. We demonstrated that compared to PDMS, OSTE has similar absorption of membrane particles and effect on enzymatic reactions, significantly lower small molecule absorption, and lower light transmission. Consequently, the immunofluorescence of OSTE LOAC was significantly impaired by OSTE optical properties. In conclusion, OSTE is a promising material for LOAC, but optical issues should be addressed in future LOAC prototypes to benefit from the material properties.

Bifurcated Asymmetric Field Flow Fractionation of Nanoparticles in PDMS-Free Microfluidic Devices for Applications in Label-Free Extracellular Vesicle Separation

“…Next, to fully characterize the microfluidic device effect on EV recovery, we compared PDMS single-channel devices with OSTE-COC polymer single-channel devices (previously shown as superior materials to PDMS in terms of small molecule adsorption for use cases in organ on the chip field) [ 16 ]. In these experiments, we used previously selected pressure as optimal-100 mBar.…”

“…Endogenic dye was used since PDMS is well known to absorb also lipophilic dyes, such as EVs membrane dyes that can create additional bias in comparison; therefore, EV nucleic acid enclosed staining was selected. There was no EV adsorption detected nether in OSTE-COC nor PDMS devices (data not showed), suggesting that the method of choice is not sensitive enough or EV loss is due to the EV bursting; thus, cargo is spilled, which requires additional analysis of lipid amount in flowthrough [ 16 ].…”

“…We have already previously discussed the importance of microfluidic material selection for application within the organ on the chip field [ 16 ]. Arguably, within the EV field, material properties play an even higher role, given the small scale and nature of the EVs, which is exacerbated by the fact that no EV quantification method provides absolute clarity on the true amount of EVs present [ 32 ].…”

“…Cyclic olefin copolymer (COC) has many advantages as the substrate of the microfluidic chips, such as biocompatibility, high chemical resistance, and small non-specific absorption as well as compatibility with large scale manufacturing, yet it is complex to assemble devices without specialized equipment [ 14 ]. Off-stoichiometry thiol-ene (OSTE) has been shown as a promising alternative to PDMS given the significantly reduced small molecule absorption yet retaining the ease of fabrication [ 15 , 16 ]. Therefore, we have combined the ease of bonding of OSTE and the superior properties of COC into a single fabrication process [ 17 ] to create improved asymmetrical flow field-flow fractionation (A4F) devices for EV isolation.…”

A Barrier to Defend - Models of Pulmonary Barrier to Study Acute Inflammatory Diseases

“…Generation of tissue models showing various physiological functions and minimal numbers of cells is necessary. The use of minimal number of cells is advantageous due to the lack of cell donors and functional cell lines and the variable composition of necessary hydrogels for efficient cell culture of organoids, stem cells or embryonic cell cultures ( 184 , 185 ). Furthermore, it is well known that physiological stimuli, such as stretching ( 186 ) fluid shear stress ( 187 ) or air contact ( 188 ), significantly alter specific functions, especially in airway cells ( 188 ).…”