Surface Modification of Polydimethylsiloxane Using Low Pressure Chemical Vapour Deposition of Poly-Chloro-p-Xylene

The capability to understand and modulate accurately the self-assembly of the extracellular matrix (ECM) components still one of the major fundamental objectives in the field of liver tissue engineering. In the present study, we put in evidence the suitability of poly-chloro-p-xylene (Parylene-C, ParC) for modulating the self-assembly of ECM (type-I collagen) microenvironment and cellular topography of human hepatocarcinoma (HepG2) and Human umbilical vascular endothelial (HUVEC) cells while coated on a polydimethylsiloxane (PDMS) substratum. Our findings demonstrated that the wettability of PDMS and ParC/PDMS were identical, while ParC/PDMS was significantly rougher than PDMS before and after collagen coating. However, the roughness and the weftability of ParC/PDMS were comparable to those of polystyrene (PS), a substratum commonly used for in vitro biological-related investigations. Type-I collagen adsorbed on ParC/PDMS and PS exhibited a dense network of microstructures around similar to 1 nm high and similar to 30-50 nm wide, whereas collagen adsorbed on PDMS had a low surface density of elongated fibrils that were 2 nm thick and similar to 200 nm wide. This disparity in ECM microarchitecture leaded to distinct culture topographies of HepG2 cells (3D and 2D for PDMS and ParC/PDMS, respectively) and viability of HUVEC (2D viable HUVEC cells and non attached dead cells on ParC/PDMS and PDMS, respectively). To conclude, the observed changes in cell morphology and viability between ParC/PDMS and PDMS alone were directly related to the nature of the material which may impact the supramolecular organization of adsorbed ECM. We strongly believe that Low Pressure Chemical Vapour deposition (LPCVD) of ParC will offer promising insights into how microscale ECM modifications directly impact cell morphology and activity, leading to the development of advanced micro/nano-sized tissue-engineered ParC/PDMS patterns with applications for liver tissue engineering.