Covalent and density-controlled surface immobilization of E-cadherin for adhesion force spectroscopy.

E-cadherin is a key cell-cell adhesion molecule but the impact of receptor density and the precise contribution of individual cadherin ectodomains in promoting cell adhesion are only incompletely understood. Investigating these mechanisms would benefit from artificial adhesion substrates carrying different cadherin ectodomains at defined surface density. We therefore developed a quantitative E-cadherin surface immobilization protocol based on the SNAP-tag technique.

Tension monitoring during epithelial-to-mesenchymal transition links the switch of phenotype to expression of moesin and cadherins in NMuMG cells.

Structural alterations during epithelial-to-mesenchymal transition (EMT) pose a substantial challenge to the mechanical response of cells and are supposed to be key parameters for an increased malignancy during metastasis. Herein, we report that during EMT, apical tension of the epithelial cell line NMuMG is controlled by cell-cell contacts and the architecture of the underlying actin structures reflecting the mechanistic interplay between cellular structure and mechanics. Using force spectroscopy we find that tension in NMuMG cells slightly increases 24 h after EMT induction, whereas upon reaching the final mesenchymal-like state characterized by a complete loss of intercellular junctions and a concerted down-regulation of the adherens junction protein E-cadherin, the overall tension becomes similar to that of solitary adherent cells and fibroblasts.

Three-dimensional microscaffolds exhibiting spatially resolved surface chemistry.

Spatial control over the surface chemistry of 3D organic-inorganic hybrid microscaffolds is achieved by a two-photon-triggered cycloaddition. Following a coating step with photoactivatable dienes via silanization, surface irradiation with a femtosecond-pulsed laser in the presence of functional dienophiles enables a site-selective alteration of the surface chemistry. Bioconjugation with fluorescent protein tags is employed to reveal the 3D molecular patterns.

SNAP-tag as a tool for surface immobilization.

SNAP-tag technology has been an important tool for protein study for more than a decade and in the meanwhile has found a number of applications beyond the field of molecular biology and protein purification. Based on covalent interaction of SNAP-tag, 20 kDA mutant of DNA repair protein and benzylguanine, it enables irreversible and controllable protein modification. In this mini review, recent developments in the use of SNAP-tag for the design of protein arrays and nanoparticle biofunctionalization are presented and discussed.

Design of chemically activated polymer microwells by one-step UV-lithography for stem cell adhesion.

A novel method to produce sub-microwalled chemically activated polymer microwells by one-step UV-lithography under ambient conditions which are selectively coated with gelatin is introduced. The dimensions as well as the shape of the resulting polystyrene structures are both tunable merely by the irradiation time through one and the same mask. It is shown that the UV-irradiation initiates three effects at those surface areas which are not covered by the mask: (i) oxidation, (ii) cross-linking, and (iii) degradation of polystyrene.