Being the newest member of the carbon materials family, graphene possesses many unique physical properties resulting is a wide range of applications. Recently, it was discovered that graphene oxide can effectively adsorb DNA and at the same time, it can completely quench adsorbed fluorophores. These properties make it possible to prepare DNA-based optical sensors using graphene oxide. While practical analytical applications are being demonstrated, the fundamental understanding of binding between graphene oxide and DNA in solution received relatively less attention. In this work, we report that the adsorption of 12, 18, 24, and 36-mer single-stranded DNA on graphene oxide is affected by several factors.For example, shorter DNAs are adsorbed faster and bind more tightly to the surface of graphene. The This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see http://dx.doi.org/10.1021/la10379262 adsorption is favored by a lower pH and a higher ionic strength. The presence of organic solvents such as ethanol can either increase or decrease adsorption depending on the ionic strength of the solution. By adding the complementary DNA, close to 100% desorption of the absorbed DNA on graphene can be achieved. On the other hand, if temperature is increased, only a small percentage of DNA is desorbed.Further, the adsorbed DNA can also be exchanged by free DNA in solution. These findings are important for further understanding the interactions between DNA and graphene and for the optimization of DNA and graphene based devices and sensors.

This review summarizes the latest developments in the shape transformation of thin, sheet-like soft materials.

Interfacing cells with nanomaterials such as graphene, nanowires, and carbon nanotubes is useful for the integration of cellular physiology with electrical read outs. Here we show the interfacing of graphene sheets on the surface of yeast cells, leading to electromechanical coupling between the sheets and the cells. The cells are viable after the interfacing. The response caused by physiologically stressing the cells by exposure to alcohols, which causes a change in cell volume, can be observed in the electrical signal through graphene. The change in the cell volume leads to straining of the sheets, forming wrinkles which reduce the electrical conductivity. As the dynamic response of the cell can be observed, it is possible to differentiate between ethanol, 2-propanol, and water. We believe this will lead to further development of cell-based electrical devices and sensors.

Graphene sheets (chemically reduced), a high modulus and high thermal and electrically conductive material are coupled with yeast cells to form an encapsulating inorganic functional layer. The coupling of the high modulus sheets with the cells increases their stability to osmotic stresses. The sheets also allow the direct visualization of the cells in an electron microscope.