Light-diffractive patterning of Porphyridium purpureum.

Light guidance is a convenient and versatile way to control the positions of phototactic microorganisms. However, the illumination strategies require adaption to the respective organism. We report on the generation of structures composed of the gliding and exopolysaccharide-secreting algae Porphyridium purpureum via their photomovement. Light patterns from a two-dimensional computer-generated hologram were projected onto inoculated agar plates. The obtained pixelated algae patterns were evaluated with regard to the illuminated intensity, contrast and pixel size. Upper and lower thresholds for algae accumulation were determined, allowing to enhance future manipulation of phototactic microorganisms.

A Perspective on Bio-Mediated Material Structuring.

Bioinspiration, biomorphy, biomimicry, biomimetics, bionics, and biotemplating are terms used to describe the fabrication of materials or, more generally, systems to solve technological problems by abstracting, emulating, using, or transferring structures from biological paradigms. Herein, a brief overview of how the different terminologies are being typically applied is provided. It is proposed that there is a rich field of research that can be expanded by utilizing various novel approaches for the guidance of living organisms for "bio-mediated" material structuring purposes. As examples of contact-based or contact-free guidance, such as substrate patterning, the application of light, magnetic fields, or chemical gradients, potentially interesting methods of creating hierarchically structured monolithic engineering materials, using live patterned biomass, biofilms, or extracellular substances as scaffolds, are presented. The potential advantages of such materials are discussed, and examples of live self-patterning of materials are given.