Versatile method to generate multiple types of micropatterns.

Micropatterning techniques have become an important tool for the study of cell behavior in controlled microenvironments. As a consequence, several approaches for the creation of micropatterns have been developed in recent years. However, the diversity of substrates, coatings, and complex patterns used in cell science is so great that no single existing technique is capable of fabricating designs suitable for all experimental conditions.

Emergence and Persistence of Collective Cell Migration on Small Circular Micropatterns.

The spontaneous formation of vortices is a hallmark of collective cellular activity. Here, we study the onset and persistence of coherent angular motion as a function of the number of cells N confined in circular micropatterns. We find that the persistence of coherent angular motion increases with N but exhibits a pronounced discontinuity accompanied by a geometric rearrangement of cells to a configuration containing a central cell.

Cellular self-organization on micro-structured surfaces.

Micro-patterned surfaces are frequently used in high-throughput single-cell studies, as they allow one to image isolated cells in defined geometries. Commonly, cells are seeded in excess onto the entire chip, and non-adherent cells are removed from the unpatterned sectors by rinsing. Here, we report on the phenomenon of cellular self-organization, which allows for autonomous positioning of cells on micro-patterned surfaces over time.

Arraying cell cultures using PEG-DMA micromolding in standard culture dishes.

A robust and effortless procedure is presented, which allows for the microstructuring of standard cell culture dishes. Cell adhesion and proliferation are controlled by three-dimensional poly(ethylene glycol)-dimethacrylate (PEG-DMA) microstructures. The spacing between microwells can be extended to millimeter size in order to enable the combination with robotic workstations.

The defined presentation of nanoparticles to cells and their surface controlled uptake.

New approaches and standardized test procedures to study the impact of nanoparticles (NPs) on living cells are urgently needed for the evaluation of potential hazards relating human exposure to NPs. Here we study semiconductor quantum dots (QDs) preparation on solid surfaces and the subsequent internalization by cells seeded on top of the NP layer. Controlled densities of NPs are adsorbed to solid surfaces coated with extra-cellular macromolecules.

Getting across the plasma membrane and beyond: intracellular uses of colloidal semiconductor nanocrystals.

Semiconductor nanocrystals (NCs) are increasingly being used as photoluminescen markers in biological imaging. Their brightness, large Stokes shift, and high photostability compared to organic fluorophores permit the exploration of biological phenomena at the single-molecule scale with superior temporal resolution and spatial precision. NCs have predominantly been used as extracellular markers for tagging and tracking membrane proteins.

Combined atomic force microscopy and optical microscopy measurements as a method to investigate particle uptake by cells.

We propose a combination of atomic force microscopy (AFM) and optical microscopy for the investigation of particle uptake by cells. Positively and negatively charged polymer microcapsules were chosen as model particles, because their interaction with cells had already been investigated in detail. AFM measurements allowed the recording of adhesion forces on a single-molecule level.