Peter Gasteier

Microcontact printing of proteins for neuronal cell guidance

The growth of neurons into networks of controlled geometry is of great interest in the field of cell-based biosensors, neuroelectronic circuits, neurological implants, pharmaceutical testing as well as fundamental biological questions about neuronal interactions. The precise control of the network architecture can be achieved by defined engineering of the surface material properties: this process is called neuronal cell patterning. Different techniques can be used to produce such surface patterns. We have chosen microcontact printing (μCP), because it is a comparatively simple and universal method for patterning biomolecules.

Ultrathin Coatings with Change in Reactivity over Time Enable Functional In Vitro Networks Of Insect Neurons

Its just not cricket! A novel coating system that enables covalent attachment of biomolecules in a nonfouling environment without use of additional chemical crosslinkers is presented. Concanavalin A is patterned on the coatings to direct cell adhesion and growth of neurons from the cricket Gryllus bimaculatus and generate functional, patterned in vitro insect neuronal networks for the first time.

Nanostructured Ordering of Fluorescent Markers and Single Proteins on Substrates

Highly ordered hexagonal nanopatterns of gold clusters on glass substrates were used as anchoring points for the specifc attachment of fluorescence dyes and proteins labeled with fluorescence dyes. Thiol‐ or disulfide‐containing linker molecules were used for the binding to the gold dots. In order to ensure specific binding on the gold dots only, the surface area in between the dots was protected against unspecific adsorption. For the attachment of polar low‐molecular‐weight fluorescence dyes, an octadecyltrichlorosilane self‐assembled monolayer was prepared on the surface in between the gold dots, whereas a layer prepared from star‐shaped poly(ethylene oxide‐stat‐propylene oxide) prepolymers was used to prevent unspecific adsorption of proteins between the gold dots. Fluorescence microscopy proved the specific binding of the dyes as well as of the proteins. Scanning force microscopy studies show that each gold dot is only capable of binding one protein at a time.

The Next Step in Biomimetic Material Design: Poly‐LacNAc‐Mediated Reversible Exposure of Extra Cellular Matrix Components

Over the last decades, biomaterials development has evolved towards strategies for biomimetic materials with better tissue integration and healing properties. [ 1 ] Surface bioactivation is one major criterion that determines biocompatibility and especially compatibility with the immune system. [ 1 , 2 ] A well-known paradigm in biomaterial research is the prevention of unspecifi c protein adsorption, which is the fi rst step in a cascade of reactions that lead to foreign body reactions. [ 1 ] Specifi c adhesive peptide sequences derived from proteins of the extracellular matrix (ECM) can be presented in a way that preserves their biological function and promotes specifi c cell adhesion on inert surfaces. [ 3 , 4 ] However, even if the use of peptide sequences has certain handling advantages compared to the use of proteins, a peptide-functionalized surface does not adequately resemble and refl ect the multifunctionality of ECM proteins and the complexity of the in vivo environment of cells. Accordingly, whole ECM proteins were covalently immobilized on inert hydrogels instead of peptide sequences to construct more biomimetic surfaces. [ 5 , 6 ] This covalent binding may, however, impact protein functionality. [ 4 ]

NCO-sP(EO-stat-PO) surface coatings preserve biochemical properties of RGD peptides.

We have previously reported that star shaped poly(ethylene oxide-stat-propylene oxide) macromers with 80% EO content and isocyanate functional groups at the distal ends [NCO-sP(EO-stat-PO)] can be used to generate coatings that are non-adhesive but easily functionalized for specific cell adhesion. In the present study, we investigated whether the NCO-sP(EO-stat-PO) surfaces maintain peptide configuration-specific cell-surface interactions or if differences between dissimilar binding molecules are concealed by the coating. To this end, we have covalently immobilized both linear-RGD peptides (gRGDsc) and cyclic-RGD (RGDfK) peptides in such coatings. Subsequently, SaOS-2 or human multipotent mesenchymal stromal cells (MSC) were seeded on these substrates. Cell adhesion, spreading and survival was observed for up to 30 days. The time span for cell adherence was not different on linear and cyclic RGD peptides, but was shorter in comparison to the unmodified glass surface. MSC proliferation on cyclic RGDfK modified coatings was 4 times higher than on films functionalized by linear gRGDsc sequences, underlining that the NCO-sP(EO-stat-PO) film preserves the configuration-specific biochemical peptide properties. Under basal conditions, MSC expressed osteogenic marker genes after 14 days on cyclic RGD peptides, but not on linear RGD peptides or the unmodified glass surfaces. Our results indicate specific effects of these adhesion peptides on MSC biology and show that this coating system is useful for selective testing of cellular interactions with adhesive ligands.