Protein spot arrays on graphene oxide coatings for efficient single-cell capture.

Biomedical applications such as cell screening or cell-cell interaction studies require placement and adhesion of cells on surfaces with controlled numbers and location. In particular, single-cell arraying and positioning has come into focus as a basis of such applications. An ideal substrate would combine biocompatibility with favorable attributes such as pattern stability and easy processing. Here, we present a simple yet effective approach to single-cell arraying based on a graphene oxide (GO) surface carrying protein (fibronectin) microarrays to define cell adhesion points. These capture NIH-3T3 cells, resulting in cell arrays, which are benchmarked against analogous arrays on silanized glass samples. We reveal significant improvement in cell-capture performance by the GO coating with regards to overall cell adhesion and single-cell feature occupancy. This overall improvement of cell-arraying combined with retained transparency of substrate for microscopy and good biocompatibility makes this graphene-based approach attractive for single-cell experiments.

Multi-color polymer pen lithography for oligonucleotide arrays.

Multi-color patterning by polymer pen lithography (PPL) was used to fabricate covalently immobilized fluorophore and oligonucleotide arrays with up to five different components. The oligonucleotide arrays offer a virtually unlimited inventory of orthogonal binding tags for self-assembly of proteins as demonstrated by use of the arrays to monitor cell-protein interactions of MCF7 cells.

A diffusive ink transport model for lipid dip-pen nanolithography.

Despite diverse applications, phospholipid membrane stacks generated by dip-pen nanolithography (DPN) still lack a thorough and systematic characterization that elucidates the whole ink transport process from writing to surface spreading, with the aim of better controlling the resulting feature size and resolution. We report a quantitative analysis and modeling of the dependence of lipid DPN features (area, height and volume) on dwell time and relative humidity. The ink flow rate increases with humidity in agreement with meniscus size growth, determining the overall feature size. The observed time dependence indicates the existence of a balance between surface spreading and the ink flow rate that promotes differences in concentration at the meniscus/substrate interface. Feature shape is controlled by the substrate surface energy. The results are analyzed within a modified model for the ink transport of diffusive inks. At any humidity the dependence of the area spread on the dwell time shows two diffusion regimes: at short dwell times growth is controlled by meniscus diffusion while at long dwell times surface diffusion governs the process. The critical point for the switch of regime depends on the humidity.

Internet-capable publication database system.

Scientific databases are generally accessible to the public via the Internet. Reports of most peer-reviewed (quotable) research is thus available to researchers and others. However, other reports and information of interest to researchers and teachers such as poster presentations at congresses, articles describing techniques and teaching material, and details of vocational and continuing education courses (nonquotable literature) generally do not appear in such databases. This nonquotable literature is often of great use to teachers. A project was therefore initiated at the Münster Dental Clinic which aimed to address the problem by developing a database of all publications and other printed material produced by the staff (faculty). After a systematic search, all such publications (quotable and nonquotable) were entered in the database which is partially accessible via the Internet and fully accessible via the Münster Dental Clinic's Intranet. The complete list can be found in the protected Intranet areas, which can be accessed by all the Dental Clinic's staff members. The database also permits Münster Clinic staff to access the Internet and locate those publications that are on the Internet by year of publication and topic.