Comparison of Biocompatibility and Adsorption Properties of Different Plastics for Advanced Microfluidic Cell and Tissue Culture Models

Abstract

Microfluidic technology is providing new routes toward advanced cell and tissue culture models to better understand human biology and disease. Many advanced devices have been made from poly(dimethylsiloxane) (PDMS) to enable experiments, for example, to study drug metabolism by use of precision-cut liver slices, that are not possible with conventional systems. However, PDMS, a silicone rubber material, is very hydrophobic and tends to exhibit significant adsorption and absorption of hydrophobic drugs and their metabolites. Although glass could be used as an alternative, thermoplastics are better from a cost and fabrication perspective. Thermoplastic polymers (plastics) allow easy surface treatment and are generally transparent and biocompatible. This study focuses on the fabrication of biocompatible microfluidic devices with low adsorption properties from the thermoplastics poly(methyl methacrylate) (PMMA), polystyrene (PS), polycarbonate (PC), and cyclic olefin copolymer (COC) as alternatives for PDMS devices. Thermoplastic surfaces were oxidized using UV-generated ozone or oxygen plasma to reduce adsorption of hydrophobic compounds. Surface hydrophilicity was assessed over 4 weeks by measuring the contact angle of water on the surface. The adsorption of 7-ethoxycoumarin, testosterone, and their metabolites was also determined after UV-ozone treatment. Biocompatibility was assessed by culturing human hepatoma (HepG2) cells on treated surfaces. Comparison of the adsorption properties and biocompatibility of devices in different plastics revealed that only UV-ozone-treated PC and COC devices satisfied both criteria. This paper lays an important foundation that will help researchers make informed decisions with respect to the materials they select for microfluidic cell-based culture experiments.

Manufacturing and wetting low-cost microfluidic cell separation devices

“…5 The materials commonly used by biologists and engineers are polystyrene (PS) and polydimethylsiloxane (PDMS), respectively. 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.…”

“…COPs are optically transparent and cyto-compatible thermoplastics exhibiting limited hydrophobic recovery after plasma treatment and low small molecule absorbance. 7 The high Young's modulus of COP may be used to reduce feature deformation during operation, when compared to PDMS. TPEs offer improved gas-permeability over thermoplastics, which is ideal for long-term cell culture and wetting complex microfluidic devices when vacuum immersion 10 is used.…”

“…The longevity of the device is attributed to the limited hydrophobic recovery of corona treated COP when compared to other materials common in microfluidics. 7 The corona treatment was used to modify the surface of COP for improved wetting, where wetting is defined as the act of completely filling the bonded channels with a fluid. The unmodified, unstructured COP is hydrophobic 7 range of contact angles allows for complete wetting while minimizing surface charges.…”

“…7 The corona treatment was used to modify the surface of COP for improved wetting, where wetting is defined as the act of completely filling the bonded channels with a fluid. The unmodified, unstructured COP is hydrophobic 7 range of contact angles allows for complete wetting while minimizing surface charges. 7 Preliminary experiments indicated the unmodified, micro-structured COP surface was super hydrophobic, exhibiting the Cassie-Baxter wetting state.…”

Robust superhydrophilic patterning of superhydrophobic ormosil surfaces for high-throughput on-chip screening applications

“…7,15 However, contact angle increases on polymer surfaces over time aer the treatment (hydrophobic recovery effect) due to the exibility and reorganization of the bonds within the polymer chains. [36][37][38] Here, we report a facile method for the generation of very stable superhydrophilic/superhydrophobic patterned surfaces. Superhydrophobic surfaces were prepared from nanostructured ormosil nanoparticles synthesized via sol-gel method where hydrophobic surface chemistry and high surface roughness were combined in one-pot approach.…”