Tuneable materials encourage bone growth

Inspired by bone growth and development, the materials mimic fontanelles present in the skulls of new born children. This connective tissue allows the baby to pass through the birth canal, but then hardens into bone to provide more protection to the growing child.

To recreate this duality, the researchers from the universities of Linköping in Sweden and Okayama in Japan began with a gel material called alginate. An electroactive polymer material was grown on one side of the gel that changes its volume when a low voltage is applied, causing the microrobot to bend in a specified direction.

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On the other side of the gel, the researchers attached biomolecules that allow the soft gel material to harden. These biomolecules are extracted from the cell membrane of a kind of cell that is central to bone development. When the material is immersed in a cell culture medium that resembles the body’s internal environment, the biomolecules make the gel mineralise and harden like bone. According to the researchers, the discovery could be used to treat complex fractures, with microbots made from the material injected into specific locations in the body to form or encourage new bone growth.