Original source: Materials Today
There’s still much for us to learn from nature. Many researchers are looking to the natural world as a source of materials to turn into new products. Materials scientists at Virginia Commonwealth University review the use and potential of natural materials for making novel functional biodevices in the journal Materials Today Bio.
“Nature is an exceptional source of inspiration,” says Vamsi Yadavalli of the author team. He explains that biomaterials are being explored to meet an increasing demand for devices that interface and integrate with biological systems. “Targets for development include sensors that provide real-time monitoring of properties such as temperature, glucose levels, electrical activity, and movement,” Yadavalli explains.
He emphasises that materials derived from plants and animals often offer benefits of environmental sustainability. They can usually be readily recycled and are derived from renewable and relatively inexpensive sources. The biocompatibility of many natural products is another key issue, allowing sensors, for example, to be attached to the skin without causing any allergic or other damaging reactions.
“Our review covers notable and creative examples of use of these materials in devices, and offers perspectives on their sourcing, processing, degradation, and biocompatibility,” Yadavalli adds. As a prominent example, he sites work that is converting natural polymers such as proteins and polysaccharides into electrically conductive materials incorporated into biocompatible sensors.
Yadavalli and his co-authors are themselves using proteins derived from silk for bioelectronic applications. In addition to acting as functional components, such as bio-derived circuits, the natural materials can also form versatile structural support materials. A crucial physical advantage of natural materials can be their flexibility, which is vital for designing wearable devices to attach to our skin or to the surface of tissues being monitored.
In addition to exploiting the electronic properties of biomaterials themselves, many composite biosensors have been constructed by imprinting metal-based circuits within a biological substrate composed of protein or carbohydrate. The proteins and carbohydrates can be extracted from a diverse range or organisms, including plants, seaweeds and marine animals such as crabs, octopuses and shrimps.
Small molecules found in nature are also being recruited into functional components. Natural pigment molecules including melanins, carotenoids and indigo have been used to form semiconducting materials that can become the basis of organic (carbon-based) diodes, capacitors and transistors. Some can be used to facilitate the movement of electrons that lies at the heart of solar cells.
DNA is also being explored as an electrical conductor that can be organised into diverse architectures, and also act as a versatile structural material. Materials with useful optical properties, such as transparent films of the carbohydrate-based chitin found in insect exoskeletons, are being explored for incorporation into opto-electronic devices.
Turning attention back to nature is partly motivated by some of the problems caused by synthetic materials. “The world is at a point where the amount of electronic and plastic waste generated each year is unsustainable,” Yadavalli points out. “Devices made of natural materials can address these issues through sustainable sourcing, greener processing and biodegradability.”
Yadavalli, V. K. et al.: “Nature-derived materials for the fabrication of functional biodevices,” Materials Today Bio (2020)