A team at Aalto University has used bacteria to produce intricately designed three-dimensional objects made of nitrocellulose. With their technique, the researchers are able to guide the growth of bacterial colonies through the use of strongly water repellent – or superhydrophobic – surfaces.
The objects show tremendous potential for medical use, including supporting tissue regeneration or as scaffolds to replace damaged organs. The results have been published in the journal ACS Nano.
Unlike fibrous objects made through current 3D printing methods, the new technique allows fibres, with a diameter a thousand times thinner than a human hair, to be aligned in any orientation, even across layers, and various gradients of thickness and topography, opening up new possibilities for application in tissue regeneration. These kinds of physical characteristics are crucial for support materials in the growth and regeneration of certain types of tissues found in muscles as well as in the brain.
Billions of tiny 3D printers
“It’s like having billions of tiny 3D printers that fit inside a bottle,” explains Luiz Greca, a doctoral student at Aalto University. ‘We can think of the bacteria as natural microrobots that take the building blocks provided to them and, with the right input, create complex shapes and structures.’
Once in a superhydrophobic mould with water and nutrients — sugar, proteins and air — the aerobic bacteria produce nanocellulose. The superhydrophobic surface essentially traps a thin layer of air, which invites the bacteria to create a fibrous biofilm replicating the surface and shape of the mould. With time, the biofilm grows thicker and the objects become stronger.
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Using the technique, the team has created 3D objects with pre-designed features, measuring from one-tenth the diameter of a single hair all the way up to 15-20 centimetres. The nano-sized fibres do not cause adverse reactions when placed in contact to human tissues. The method could also be used to grow realistic models of organs for training surgeons or improving the accuracy of in-vitro testing.
Source: Aalto University
• This article originally appeared on technology.org
