Protein patterns of different shapes and densities are useful tools for studies of cell behavior and to create biomaterials that induce specific cellular responses. Up to now the dominant techniques for creating protein patterns are mostly based on serial writing processes or require templates such as photomasks or elastomer stamps. Only a few of these techniques permit the creation of grayscale patterns. Herein, the development of a lithography system using a digital mirror device which allows fast patterning of proteins by immobilizing fluorescently labeled molecules via photobleaching is reported. Grayscale patterns of biotin with pixel sizes in the range of 2.5 μm are generated within 10 s of exposure on an area of about 5 mm(2) . This maskless projection lithography method permits the rapid and inexpensive generation of protein patterns definable by any user-defined grayscale digital image on substrate areas in the mm(2) to cm(2) range.

Multiplexing, i.e., the application and integration of more than one ink in an interdigitated microscale pattern, is still a challenge for microcontact printing (μCP) and similar techniques. On the other hand there is a strong demand for interdigitated patterns of more than one protein on subcellular to cellular length scales in the lower micrometer range in biological experiments. Here, a new integrative approach is presented for the fabrication of bioactive microarrays and complex multi-ink patterns by polymer pen lithography (PPL). By taking advantage of the strength of microcontact printing (μCP) combined with the spatial control and capability of precise repetition of PPL in an innovative way, a new inking and writing strategy is introduced for PPL that enables true multiplexing within each repetitive subpattern. Furthermore, a specific ink/substrate platform is demonstrated that can be used to immobilize functional proteins and other bioactive compounds over a biotin-streptavidin approach. This patterning strategy aims specifically at application by cell biologists and biochemists addressing a wide range of relevant pattern sizes, easy pattern generation and adjustment, the use of only biofriendly, nontoxic chemicals, and mild processing conditions during the patterning steps. The retained bioactivity of the fabricated cm(2) area filling multiprotein patterns is demonstrated by showing the interaction of fibroblasts and neurons with multiplexed structures of fibronectin and laminin or laminin and ephrin, respectively.

The cover picture shows that chemical and biological knowledge need to be linked more to ensure that highly effective and target‐specific drugs can be found more quickly. Additionally, the main and side effects must be controlled in the best interests of the individual patient. Despite the intensive use of high‐throughput technologies in drug research, despite new insight in genomic and proteomic research and in structural biology, and despite the progress made in bio‐ and chemoinformatics, there is still a worldwide shortage of new and innovative drugs. The bottleneck in lead‐structure generation lies in the preparation of new biologically relevant substances and therefore to a major extent in chemistry. The way medicinal chemists perceive their subject and its role in the natural sciences as well as in the value chain of drug research is crucial to counteract this shortage, as explained by Wess et al. on page 3341–3350.

future applications. To obtain biofunctional surfaces, amongst others the mode of immobilization, the distribution of the tethered molecules on a micrometer scale and the microtopography of the substrate need to be tailored. [ 2 ] So far, in vitro studies were mainly carried out on planar surfaces. To permit highly miniaturized and thus parallelized assays with low compound consumption, for instance to test the response of cells to effector molecules, microarrays of protein or ligandcoated spots ranging from 100-500 μ m in diameter can be produced by microcontact printing, spotting or patterning with microfl uidic networks. [ 3 ] To investigate the role of surface bound chemical cues on cell behavior, often patterns of biomolecules, particularly proteins, such as growth factors or cell adhesion proteins, have to be created. Biologically active molecules can be immobilized on chemically modifi ed patterns on the substrate. As in the production of microarrays, spatially-defi ned patterns of functional groups have been generated by microcontact printing [ 4 ] and microfl uidic networks, [ 5 ] but they can also be drawn by dip pen nanolithography (DPN) using the tip of a probe controlled by an atomic force microscope, [ 6 ] or created by mask-based lithography with biocompatible resists. [ 7 ] Another option to obtain patterns of functional groups is chemical vapor deposition (CVD) polymerization of [2.2]paracyclophane derivatives. [ 8 ] This

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