The messy world of biology and traditional clean-room inorganic electronics may seem an unlikely alliance, but combining the two could provide an invaluable interface for obtaining and interpreting sophisticated biological and chemical molecular information. With this in mind, Choi and the researchers in his bioelectronics lab at Sogang University in Korea, have been investigating a range of biohybrid devices.

An example of their research is the bioprocessor that uses DNA to combine a gold particle and a biological metalloprotein. Choi explained how an inorganic component such as the gold nanoparticle could fulfil basic processing functions such as the “reinforcement”, “regulation” and “amplification” of information, while the redox characteristics of the protein provided memory states.

He went on to describe the potential of further work to develop similar devices that could penetrate and control cells. “So what next?” he added, inviting the Nano Korea attendees to consider systems such as a cerebral cortex, basal ganglia or cerebellum on a chip. In fact, his group has already demonstrated the ability to control the differentiation of cells using patterned graphene oxide, as well as magnetic fields that can direct the growth of neurites.

A grand project that harnesses the state of the art in biohybrid devices is the artificial ray reported by a team of researchers at Harvard and Stanford Universities in the US and Sogang University (including Choi) in Korea in Science earlier this month. “Through this interdisciplinary collaboration led by Kevin Kit Parker at Harvard it was possible to find solutions to a range of issues: tissue-engineering techniques and bioinspired design (Parker group, Harvard), hydrodynamics and analytical solution (Mahadevan group, Harvard), fish fluid dynamics and bioinspired design (Lauder group, Harvard), optogenetics (Deisseroth Group, Stanford) and biomaterials (our group, Sogang University, Seoul, Korea),” explained Choi.

The collaboration of researchers created an inorganic gold skeleton on an elastomer substrate, and added a further elastomer layer and a musculoskeleton, allowing the “device” to move like a ray. The team then enrolled optogenetics through the incorporation of muscle cells – myocytes – that had been genetically engineered to express light-sensitive ion channels, so that the artificial ray could also respond to light.

Biosensors

More immediate practical applications of bioprocessors might exploit the flexibility and biocompatibility of such devices for monitoring bodily functions. This need is also met by the nanowire sensors described by John Rogers from the University of Illinois in his Nano Korea 2016 key note talk.

Although silicon is inert in the bulk, as with many other semiconductors at the nanoscale, it dissolves in fluid so that such biosensors become resorbable. This combined with their flexibility is a huge advantage, as illustrated in the example Rogers gave of a pressure sensor inserted to monitor the brain following severe traumatic injury. A monitor that subsequently dissolves after use would obviate the need for further risky surgery to extract it.

Other biohybrids

Another advantage of working with biological systems is the ability to exploit solutions found in nature for device challenges. Despite advances in solar cells, the photosynthesis in plants still beats the efficiency of artificial photovoltaic systems. Combining biological systems with inorganic materials could provide a valuable means of exploiting photosynthesis in artificial devices.

Speaking to nanotechweb.org after his talk, Choi expressed interest in the energy-harvesting potential of biohybrid devices. He suggested how the bioprocessing systems developed in his lab might potentially be adapted for photovoltaics by using a photodegradable molecule that releases a current during degradation. For more of the latest research on biohybrid devices, visit the collection coming soon to Nanotechnology’s focus collections.