An Injection-Molded Modified Silicone Rubber for Cancer-on-Chip Applications

For drug screening and personalized medicine approaches, cancer-on-chip (CoC) models are valuable as these systems enable precise control of cellular and tissue architecture and can be equipped with micro-sensors for real-time monitoring of physiological responses to drugs. Accurate design of the microfluidic device is important to allow recapitulation of key factors of a tumor and its microenvironment. Polydimethylsiloxane (PDMS) is widely used as material for microfluidics due to its favorable characteristics including low cost, suitability for rapid prototyping, optical transparency, and biocompatibility. However, the hydrophobic nature of PDMS complicates its use in microfluidic devices. Here, the characterization and application of an injection-molded functionalized PDMS fluidic insert for the commercially available Micronit system are described. The injection-molded PDMS has been modified with carboxyl groups to accommodate cell culture on its surface and to covalently bind proteins for long-lasting coating of the PDMS surface required for flow-conditions. Modification of PDMS does not change its favorable properties such as its high optical transparency and absence of auto-fluorescence. The modified PDMS fluidic inserts are suitable for building relevant cancer models on chip and do not show absorption of small molecules such as doxorubicin, allowing their use for drug screening and personalized medicine approaches on chip.