Abstract
Polydimethylsiloxane (PDMS) is a promising biomaterial for generating artificial extracellular matrix (ECM) like patterned topographies, yet its hydrophobic nature limits its applicability to cell-based approaches. Although plasma treatment can enhance the wettability of PDMS, the surface is known to recover its hydrophobicity within a few hours after exposure to air. To investigate the capability of a novel PDMS-type (X-PDMS) for in vitro based assessment of physiological cell properties, we designed and fabricated plane as well as nano- and micrometer-scaled pillar-patterned growth substrates using the elastomer types S-, H- and X-PDMS, which were fabricated from commercially available components. Most importantly, we compared X-PDMS based growth substrates which have not yet been investigated in this context with H- as well as well-known S-PDMS based substrates. Due to its applicability to fabricating nanometer-sized topographic features with high accuracy and pattern fidelity, this material may be of high relevance for specific biomedical applications. To assess their applicability to cell-based approaches, we characterized the generated surfaces using water contact angle (WCA) measurement and atomic force microscopy (AFM) as indicators of wettability and roughness, respectively. We further assessed cell number, cell area and cellular elongation as indirect measures of cellular viability and adhesion by image cytometry and phenotypic profiling, respectively, using Calcein and Hoechst 33342 stained human foreskin fibroblasts as a model system. We show for the first time that different PDMS types are differently sensitive to plasma treatment. We further demonstrate that surface hydrophobicity changes along with changing height of the pillar-structures. Our data indicate that plane and structured X-PDMS shows cytocompatibility and adhesive properties comparable to the previously described elastomer types S- and H-PDMS. We conclude that nanometer-sized structuring of X-PDMS may serve as a powerful method for altering surface properties toward production of biomedical devices for cell-based applications.
Highlights
In a step we evaluated the characteristics with regard to wettability, roughness and applicability to cell-based approaches using HFF-1 cells as a model system
More importantly, our results demonstrate for the first time, that growth substrates fabricated from X-PDMS are as suitable for cell-based approaches as previously characterized S- and H-PDMS surfaces
In order to obtain an estimate regarding the applicability for cell-based approaches, we evaluated the characteristics of the generated surfaces with regard to wettability and roughness using water contact angle (WCA) measurement and atomic force microscopy, respectively
Summary
Cellular physiology and viability as well as the cells’ ability to migrate, to proliferate or to interact with an artificial growth surface in vitro or the extracellular matrix (ECM) in vivo, strongly depend on the properties of local structural and physical characteristics, including wettability, three-dimensional topography and stiffness (Discher et al, 2005; Yim et al, 2005; Bettinger et al, 2009; Martínez et al, 2009; Hwang et al, 2010; Ranella et al, 2010; Dowling et al, 2011; Rupp et al, 2014; Song and Ren, 2014; Keshavarz et al, 2016; Moyen et al, 2016). For in vitro-based assessment of the physiological properties of cells in vivo, improved platforms for biomedical applications, such as lab-on-a-chip devices, providing an artificial nano- to micrometer-structured environment that mimics a patterned topography of the native ECM, are urgently required (Li and Kilian, 2015). H-PDMS is a more rigid PDMS type with a comparably higher Young’s modulus (8– 12 MPa) This material has proven to be suitable for generating sub-micrometer-patterned structures, it has shown to be unsuitable for fabricating nanometer-sized structures with high aspect ratios (Verschuuren, 2010; Schmitt et al, 2012; Scharin et al, 2014). X-PDMS has proven suitable for the production of structures in the nanometer range with high accuracy and reproducibility (Verschuuren, 2010)
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