UV light used to alter semiconductor properties

Researchers in the US have developed a bioelectronic interface that manipulates the behaviour of cells on semiconductor materials by using UV light to alter the conductivity of the material.

(Credit: Phil Whitehouse via flickr)

“There’s a great deal of interest in being able to control cell behaviour in relation to semiconductors – that’s the underlying idea behind bioelectronics,” said Albena Ivanisevic, a professor of materials science and engineering at North Carolina State University (NC State) and corresponding author of the study. “Our work here effectively adds another tool to the toolbox for the development of new bioelectronic devices.”

The new approach is said to make use of persistent photoconductivity. Materials that exhibit persistent photoconductivity become more conductive when light is shone on them. When the light is removed, it takes the material a long time to return to its original conductivity.

According to NC State, when conductivity is elevated, the charge at the surface of the material increases and that increased surface charge can be used to direct cells to adhere to the surface.

“This is only one way to control the adhesion of cells to the surface of a material,” Ivanisevic said. “But it can be used in conjunction with others, such as engineering the roughness of the material’s surface or chemically modifying the material.”

For this study, the researchers demonstrated that all three characteristics can be used together, working with a gallium nitride substrate and PC12 cells used widely in bioelectronics testing.

The researchers tested two groups of gallium nitride substrates that were identical, except that one group was exposed to UV light – triggering its persistent photoconductivity properties – while the second group was not.

“There was a clear, quantitative difference between the two groups – more cells adhered to the materials that had been exposed to light,” Ivanisevic said. “This is a proof-of-concept paper. We now need to explore how to engineer the topography and thickness of the semiconductor material in order to influence the persistent photoconductivity and roughness of the material. Ultimately, we want to provide better control of cell adhesion and behaviour.”

The paper, “Persistent Photoconductivity, Nanoscale Topography and Chemical Functionalization Can Collectively Influence the Behavior of PC12 Cells on Wide Band Gap Semiconductor Surfaces,” is published in the journal Small.