In detail: Building with Bacteria

Studying the nanostructure of bacteria and microorganisms offers a way to increase the strength and flexibility of synthetic materials, suggests new research from Europe.

The most useful properties of natural materials, such as strength, degradability, permeability and flexibility, are close to impossible to replicate in synthetics. “In nature, we find many materials with properties that artificial materials are unable to replicate in the exact same fashion,” says Professor Cordt Zollfrank, Chair of Biogenic Polymers at TUM Straubing Campus for Biotechnology and Sustainability, talking to TUM’s news website. Biotemplating - or copying the nanostructure of natural materials into artificial ones - is the only way, so far, to achieve these useful, finer properties without growing the material itself.

Nature has always provided inspiration for technology – from birds inspiring aeroplane wings and aerodynamics, to burdocks caught in dog’s fur inspiring Velcro. The advent of 3D printing and the ability to print materials at a molecular level, has opened new possibilities for biomimicry at the minute level.

Following this, a team at TUM headed by Dr Daniel Van Opdenbosch and under Professor Zollfrank’s chair, has been investigating the properties of red algae. Under the microscope, red algae blooms are characterised by finger-like tendrils. The tendrils grow towards light, secreting sugar molecules behind them in fine polymer threads. The team’s research focuses on manipulating the algae’s exposure to light to make it grow in certain ways, concentrating on the polymer threads. This custom structure can then be used as a template for manufacturing functional materials such as ceramics. The hope is that the blueprint could even be used to construct battery electrodes, screen and display technologies, and medicinal products including replacement bone and tissue.

The TUM lab’s paper highlights that this is a new direction for bionic research. “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” states Van Opdenbosch and his co-authors. Bio-mediated here meaning that the process of building a material is directed in part an external force. This research puts forward five experiments for materials that can be bio-mediated, including red algae, and also proposes additional contact-free guidance systems using magnetic fields or chemical gradients – depending on the material used. “These biological findings for controlling microbes via targeted stimuli will shape the future of material research,” predicts Professor Cordt Zollfrank for TUM news.

Beyond mapping natural structures to improve artificial materials, the next step in biotemplating and bionics is to be able to control microorganisms enough for them to build human-designed complex microstructures. Early investigations into this include MIT Media Lab’s pavilion, which was woven by combination of silkworms and robots. A robotic arm was taught to mimic the weaving patterns of silkworms. Once the initial structure was finished, silkworms completed the work, guided by environmental factors controlled by MIT.

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