Culturing Cells on Flexible Substrates of High Refractive Indexes

ABSTRACTMechanical cues in cellular microenvironment are central in directing a class of cellular behaviors such as the dynamic of cell adhesion, migration, and differentiation. Several advanced optical techniques, such as structured-illumination nano-profilometry (SINAP), have been developed for a better resolution of these dynamic processes. These techniques however require culturing cells on materials of refractive index close to that of glass, while most studies regarding the effects of mechanical cues on cellular dynamics were conducted on hydrogel-based substrates. Here we report the development of culturing substrates of tunable rigidity and refractive index suitable for SINAP studies. Polyvinyl chloride (PVC)-based substrates were mixed with a softener called Di(isononyl) Cyclohexane-1,2-Dicarboxylate (DINCH) and cured by heating. The volume ratios of PVC to DINCH were varied from 1:1 to 3:1. The Young’s modulus of the resulting substrates ranged from 18 kPa to 40 kPa. The yielded refractive indices of the composite substrates as measured by phase contrast tomography ranged from 1.47 to 1.53. Human lung adenocarcinoma cells CL1-5 were cultured on the composite substrates and cell viability was examined using the MTT assay. The dynamics of cell adhesion and filopodia activities were examined using SINAP. Preliminary results suggest that PVC based culturing substrates have a great potential in the application of SINAP based studies.