High-throughput screening (HTS) methods based on topography gradients or arrays have been extensively used to investigate cell–material interactions. However, it is a huge technological challenge to cost efficiently prepare topographical gradients of inorganic biomaterials due to their inherent material properties. Here, we developed a novel strategy translating PDMS-based wrinkled topography gradients with amplitudes from 49 to 2561 nm and wavelengths between 464 and 7121 nm to inorganic biomaterials (SiO2, Ti/TiO2, Cr/CrO3, and Al2O3) which are frequently used clinical materials. Optimal substratum conditions promoted human bone-marrow derived mesenchymal stem cell alignment, elongation, cytoskeleton arrangement, filopodia development as well as cell adhesion in vitro, which depended both on topography and interface material. This study displays a positive correlation between cell alignment and the orientation of cytoskeleton, filopodia, and focal adhesions. This platform vastly minimizes the experimental efforts both for inorganic material interface engineering and cell biological assessments in a facile and effective approach. The practical application of the HTS technology is expected to aid in the acceleration of developments of inorganic clinical biomaterials.

A novel approach was developed using PDMS-substrates with surface-aligned nanotopography gradients, varying unidirectional in amplitude and wavelength, for studying cell behavior with regard to adhesion and alignment. The gradients target more surface feature parameters simultaneously and provide more information with fewer experiments and are therefore vastly superior with respect to individual topography substrates. Cellular adhesion experiments on non-gradient aligned nanowrinkled surfaces displayed a linear relationship of osteoblast cell adhesion with respect to topography aspect ratio. Additionally, an aspect ratio of 0.25 was found to be most efficient for cell alignment. Modification of the surface preparation method allowed us to develop an approach for creating surface nanotopography gradients which innovatively provided a superior data collection with fewer experiments showing that 1) low amplitude with small wavenumber is best for osteoblast cell adhesion 2) indeed higher aspect ratios are favorable for alignment however only with features between 80–180 nm in amplitude and 450–750 nm in wavelength with a clear transition between adhesion and alignment efficiency and 3) disproved a linear relationship of cell adhesion towards aspect ratio as was found for single feature substrate analysis.

This study demonstrates the effect of polymer topology and molar mass on the electrodeposition of preformed polyelectrolytes. The polyelectrolyte solubility is manipulated electrochemically using a counterion switching approach. Upon this, a triggered film formation occurs upon oxidation of hexacyanoferrate(II). The resulting Pt-electrode deposit consists of polycationic chains, namely poly{[2-(methacryloyloxy)ethyl]trimethylammonium chloride} (PMOTAC), which are physically crosslinked by polymer-complexing ferricyanides. Within this study the architecture of the polyelectrolyte is varied from monomeric units over linear and star-shaped polymers to network-like microgel colloids. Film deposition is observed only for linear and star-shaped polymers being pronounced for shorter linear chains at equimolar charge ratios. Quantification is achieved by help of the deposition efficiency DE obtained by analyzing the currents of a rotating ring disk electrode (RRDE) during hydrodynamic voltammetry. DE relates the amount of deposited ferricyanides to the total amount of electrochemically-produced ferricyanides. DE is used to estimate the deposited mass and film thickness showing good agreement with the film thickness determined experimentally by Scanning Force Microscopy. For future applications these results might help optimizing beneficial film formation or minimizing detrimental film formation during other procedures.