TY - JOUR A1 - Biela, Sarah A1 - Striegl, Britta A1 - Frey, Kerstin A1 - Spatz, Joachim A1 - Kemkemer, Ralf T1 - Distance-dependent adhesion of vascular cells on biofunctionalized nanostructures JF - Current directions in biomedical engineering N2 - Cell-cell and cell-extracellular matrix (ECM) adhesion regulates fundamental cellular functions and is crucial for cell-material contact. Adhesion is influenced by many factors like affinity and specificity of the receptor-ligand interaction or overall ligand concentration and density. To investigate molecular details of cell ECM and cadherins (cell-cell) interaction in vascular cells functional nanostructured surfaces were used Ligand-functionalized gold nanoparticles (AuNPs) with 6-8 nm diameter, are precisely immobilized on a surface and separated by non-adhesive regions so that individual integrins or cadherins can specifically interact with the ligands on the AuNPs. Using 40 nm and 90 nm distances between the AuNPs and functionalized either with peptide motifs of the extracellular matrix (RGD or REDV) or vascular endothelial cadherins (VEC), the influence of distance and ligand specificity on spreading and adhesion of endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. We demonstrate that RGD-dependent adhesion of vascular cells is similar to other cell types and that the distance dependence for integrin binding to ECM-peptides is also valid for the REDV motif. VEC-ligands decrease adhesion significantly on the tested ligand distances. These results may be helpful for future improvements in vascular tissue engineering and for development of implant surfaces. KW - cell adhesion KW - nanostructure KW - vascular cells KW - adhesive peptides Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bsz:rt2-opus4-17418 SN - 2364-5504 VL - 3 IS - 2 SP - 683 EP - 686 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Frey, Kerstin A1 - Fischer, Alena A1 - Krastev, Rumen A1 - Kemkemer, Ralf T1 - CurvChip - chip platform for investigating cell responses to curved surface features JF - Current directions in biomedical engineering N2 - Surface topographies are often discussed as an important parameter influencing basic cell behavior. Whereas most in vitro studies deal with microstructures with sharp edges, smooth, curved microscale topographies might be more relevant concerning in-vivo situations. Addressing the lack of highly defined surfaces with varying curvature, we present a topography chip system with 3D curved features of varying spacing, curvature radii as well as varying overall dimensions of curved surfaces. The CurvChip is produced by low-cost photolithography with thermal reflow, subsequent (repetitive) PDMS molding and hot embossing. The platform facilitates the systematic in-vitro investigation of the impact of substrate curvature on cell types like epithelial, endothelial, smooth muscle cells, or stem cells. Such investigations will not only help to further understand the mechanism of curvature sensation but may also contribute to optimize cell-material interactions in the field of regenerative medicine. KW - photolithography KW - thermal reflow KW - topography with defined 3D curvature KW - chip platform Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bsz:rt2-opus4-21505 SN - 2364-5504 VL - 4 IS - 1 SP - 453 EP - 456 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Yang, Linxiao A1 - Zhang, Zenghao A1 - Athanasopulu, Kiriaki A1 - Frey, Kerstin A1 - Cui, Zhishan A1 - Su, Haijia A1 - Luo, Liu A1 - Kemkemer, Ralf T1 - Surface modification of Polydimethylsiloxane by hydrogels for microfluidic applications JF - Current directions in biomedical engineering N2 - In vitro, hydrogel-based ECMs for functionalizing surfaces of various material have played an essential role in mimicking native tissue matrix. Polydimethylsiloxane (PDMS) is widely used to build microfluidic or organ-on-chip devices compatible with cells due to its easy handling in cast replication. Despite such advantages, the limitation of PDMS is its hydrophobic surface property. To improve wettability of PDMS-based devices, alginate, a naturally derived polysaccharide, was covalently bound to the PDMS surface. This alginate then crosslinked further hydrogel onto the PDMS surface in desired layer thickness. Hydrogel-modified PDMS was used for coating a topography chip system and in vitro investigation of cell growth on the surfaces. Moreover, such hydrophilic hydrogel-coated PDMS is utilized in a microfluidic device to prevent unspecific absorption of organic solutions. Hence, in both exemplary studies, PDMS surface properties were modified leading to improved devices. KW - PDMS KW - alginate KW - hydrogel KW - microfluidic chips KW - cell culture Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bsz:rt2-opus4-23949 SN - 2364-5504 VL - 5 IS - 1 SP - 93 EP - 96 PB - De Gruyter CY - Berlin ER -