Cytotoxicity was determined by a colorimetric assay, which measures released LDH activity. LDH enzyme is released into

the cell culture when the membrane is damaged. So, an increase of LDH has been associated with a cellular injury. After a period of 48 h, the production of LDH activity released increases in the porous silicon substrates and also in the blank control (cells incubated without silicon substrates). These results indicate that the presence of the silicon in the culture medium does not cause cytotoxicity per se. To quantify viability of cells grown on surface porous silicon, we assessed the morphology using phase-contrast microscopy and by trypan blue exclusion (Merck & Co., Inc.). The cell viability of HAECs was >97% in all the porous substrates. Conclusions Silicon substrates with pore size in the macro- and nanoporous range have been used to study Entospletinib concentration the adhesion and the morphology of endothelial cells. The substrates were functionalized previously, with APTES in order to improve the adhesion. SEM characterization shows that different pore geometries induced different cellular response in terms of cell adhesion and morphology. On macroporous silicon, the pseudopods R406 of the cell can grow along the macropore, and the cells show 2-D and 3-D migration behaviors. On nanoporous substrates, filopodia was found to branch out from the main cell body, which anchors the cell to the substrate. From fluorescence microscopy, limited information on cell

morphology to qualify the cell development on these silicon substrates is obtained. These two forms of porous silicon, macro and nano, are promising substrates for developing new 3-D cell culture platforms with applications in tissue

engineering as well as basic cell biology research. Acknowledgements This work was supported by the buy P5091 Spanish Ministerio de Economía y Competividad (MINECO) under grant number TEC2012-34397, Generalitat de Catalunya under grant number 2014-SGR-1344, Spanish Nutlin-3 manufacturer Ministerio de Educación y Ciencia AGL2012-40144-C03-02, and the support of Centre Tecnològic de Nutrició i Salut (CTNS). References 1. Bhattacharyya D, Xu H, Deshmukh RR, Timmons RB, Nguyen KT: Surface chemistry and polymer film thickness effects on endothelial cell adhesion and proliferation. J Biomed Mater Res A 2010, 2:640–648. 2. Kasemo B: Biological surface science. Surf Sci 2002, 500:656–677. 10.1016/S0039-6028(01)01809-XCrossRef 3. Anderson SHC, Elliot H, Wallis DJ, Canham LT, Powell JJ: Dissolution of different forms of partially porous silicon wafers under simulated physiological conditions. Phys Status Solid A 2003, 97:331–335.CrossRef 4. Park JH, Gu L, von Maltzahn G, Ruoslahti E, Bhatia SN, Sailor MJ: Biodegradable luminescent porous silicon nanoparticles for in vivo applications. Nat Mater 2009, 8:331–336. 10.1038/nmat2398CrossRef 5. Canham LT: Bioactive silicon structure fabrication through nanoetching techniques. Adv Mater 1995, 7:1033–1037. 10.1002/adma.19950071215CrossRef 6.