Improved cell adhesion under shear stress in PDMS microfluidic devices.

Microfluidic systems based on polydimethylsiloxane (PDMS) provide a versatile platform to study the mechanoresponse of cells in vitro. Under a shear flow, however, the stability of cells that were grown on physically adsorbed proteins is short lived, which limits long-term cell studies. To address this issue, we used (3-Aminopropyl)triethoxysilane (APTES) as a linker between PDMS and collagen. In micro-channels that were modified with APTES-anchored collagen, fibroblast cells demonstrated higher stability and better proliferation as compared to collagen that was physically adsorbed onto PDMS after oxygen plasma treatment. To assess the stability of the cellular adhesion, cells were forced in a shear flow until detachment. In devices with APTES-anchored collagen, cells showed better adhesion and proliferation at shear stresses between 11.6 and 93dyn/cm2 as compared to devices with the adsorbed collagen coating where the first cellular detachment occurred already at a shear stress of 23dyn/cm2 . The APTES-attached collagen coating also contributed to an improved long-term cellular growth (observed for 48h) at different shear stress levels (10-300dyn/cm2 ). Attachment of collagen with the help of APTES thus is a very promising technique not only to modify the glass but also to modify the PDMS surfaces of microfluidic devices for mechanotransduction experiments.