Seunghun Hong

Graphene-substrate-promoted human neural stem cell adhesion and its differentiation into neurons is reported. Microarray studies were performed to explore plausible explanation for this effect. Further, an electrical stimulation on differentiated cells via graphene electrodes is demonstrated. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the au

The development of an eight-pen nanoplotter capable of doing parallel dip-pen nanolithography (DPN) is reported. Because line width and patterning speed in DPN are independent of contact force, only one of the tips in the parallel writing mode (the "imaging" tip) has a feedback system to monitor tip position and to write the pattern; all other tips reproduce what occurs at the imaging tip in a passive fashion. Proof-of-concept experiments that demonstrate eight-pen parallel writing, ink and rins

The development of reagents with high affinity and specificity to small molecules is crucial for the high-throughput detection of chemical compounds, such as toxicants or pollutants. Aptamers are short and single-stranded (ss) oligonucleotides able to recognize target molecules with high affinity. Here, we report the selection of ssDNA aptamers that bind to Bisphenol A (BPA), an environmental hormone. Using SELEX process, we isolated high affinity aptamers to BPA from a 10(15) random library of

A directed-assembly method on the basis of graphene oxide (GO) pieces is developed, which allowed us to mass-produce a uniform array of graphene-based ambipolar memory devices using only conventional microfabrication facilities. Significantly, we successfully demonstrated that this device can be operated as both conventional conductivity-switching memory and new type-switching memory by adjusting the charge density on the nanoparticles.

We developed a simple but efficient method to mass-produce highly flexible and high-performance photodetectors based on aligned cadmium sulfide (CdS) nanowire (NW) networks. In this method, the CdS NWs were selectively aligned along the molecular patterns on flexible substrates via a direct assembly method, and the aligned CdS NW patterns were utilized as the channels of flexible photodetectors. The photodetectors based on the aligned CdS NWs exhibited ∼10 times higher photosensitivity and ∼100

We have developed a method to monitor the activities of human taste receptor protein in lipid membrane using carbon nanotube transistors, enabling a "bioelectronic super-taster (BST)", a taste sensor with human-tongue-like selectivity. In this work, human bitter taste receptor protein expressed in E. coli was immobilized on a single-walled carbon nanotube field effect transistor (swCNT-FET) with the lipid membrane. Then, the protein binding activity was monitored using the underlying swCNT-FET,

A portable sensor platform for the detection of small molecular species is crucial for the on-site monitoring of environmental pollutants, food toxicants, and disease-related metabolites. However, it is still extremely difficult to find highly selective and sensitive sensor platforms for general small molecular detection. Herein, we report aptamer sandwich-based carbon nanotube sensor strategy for small molecular detection, where aptamers were utilized to capture target molecules as well as to e

Controlled osteogenic differentiation of human mesenchymal stem cells (hMSCs) is initiated with the use of only single-walled carbon nanotube structures without any bio/chemical treatment. Oxygen plasma treatment of the carbon nanotubes is found to enhance the vitality of the hMSCs and promote osteogenic commitment. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made availabl

A new tool for studying self-assembled monolayer (SAM) nucleation and growth processes on faceted inorganic substrates under ambient conditions is reported herein. The methodology involves coating an atomic force microscope tip with molecules of interest and raster scanning across a substrate of interest with the modified tip. Large scale images of the deposition process provide kinetic information about the nucleation and growth of SAMs. The water meniscus, which is the transport medium in thes

Graphene–CdS nanowire (NW) hybrid structures with high-speed photoconductivity were developed. The hybrid structure was comprised of CdS NWs which were selectively grown in specific regions on a single-layer graphene sheet. The photoconductive channels based on graphene–CdS NW hybrid structures exhibited much larger photocurrents than graphene-based channels and much faster recovery speed than CdS NW network-based ones. Our graphene–CdS NW structures can be useful because they were much faster t