Porous nanocrystalline silicon membranes as highly permeable and molecularly thin substrates for cell culture

Porous nanocrystalline silicon (pnc-Si) is new type of silicon nanomaterial with potential uses in lab-on-a-chip devices, cell culture, and tissue engineering. The pnc-Si material is a 15 nm thick, freestanding, nanoporous membrane made with scalable silicon manufacturing. Because pnc-Si membranes are approximately 1000 times thinner than any polymeric membrane, their permeability to small solutes is orders-of-magnitude greater than conventional membranes. As cell culture substrates, pnc-Si membranes can overcome the shortcomings of membranes used in commercial transwell devices and enable new devices for the control of cellular microenvironments. The current study investigates the feasibility of pnc-Si as a cell culture substrate by measuring cell adhesion, morphology, growth and viability on pnc-Si compared to conventional culture substrates. Results for immortalized fibroblasts and primary vascular endothelial cells are highly similar on pnc-Si, polystyrene and glass. Significantly, pnc-Si dissolves in cell culture media over several days without cytotoxic effects and stability is tunable by modifying the density of a superficial oxide. The results establish pnc-Si as a viable substrate for cell culture and a degradable biomaterial. Pnc-Si membranes should find use in the study of molecular transport through cell monolayers, in studies of cell-cell communication, and as biodegradable scaffolds for three-dimensional tissue constructs.