Imaging techniques for diagnosing muscle atrophy and sarcopenia remain insufficient, although various advanced diagnostic methods have been established. We explored the feasibility of 18F-fluorocholine (18F-FCH) positron emission tomography/computed tomography (PET/CT) for evaluating skeletal muscle atrophy, as an imaging technique that tracks choline level changes in muscles. Cell uptake in L6 cells by 18F-FCH was performed in a complete medium containing serum (untreated group, UN) and a serum-free medium (starved group, ST). Small-animal-dedicated PET/CT imaging with 18F-FCH was examined in in-vivo models with rats that were starved for 2 days to cause muscle atrophy. After the hind limbs were dissected, starvation-induced in-vivo models were anatomically confirmed by reverse-transcription polymerase chain reaction to evaluate the expression levels of the atrophy markers muscle RING-finger protein-1 (MuRF-1) and atrogin-1. 18F-FCH uptake was lower in the starvation-induced cells than in the untreated group, and in-vivo PET uptake also revealed a similar tendency (the average standardized uptake value (SUVmean) = 0.26 ± 0.06 versus 0.37 ± 0.07, respectively). Furthermore, the expression levels of MuRF-1 and atrogin-1 mRNA were significantly increased in the starvation-induced muscle atrophy of rats compared to the untreated group. 18F-FCH PET/CT may be a promising tool for diagnosing skeletal muscle atrophy.

We present receptor-modified carbon nanotube sensors for the highly selective and sensitive detection of acetylcholine (ACh), one kind of neurotransmitter. Here, we successfully expressed the M1 muscarinic acetylcholine receptor (M1 mAChR), a family of G protein-coupled receptors (GPCRs), in E. coli and coated single-walled carbon nanotube (swCNT)-field effect transistors (FETs) with lipid membrane including the receptor, enabling highly selective and sensitive ACh detection. Using this sensor, we could detect ACh at 100 pM concentration. Moreover, we showed that this sensor could selectively detect ACh among other neurotransmitters. This is the first demonstration of the real-time detection of ACh using specific binding between ACh and M1 mAChR, and it may lead to breakthroughs for various applications such as disease diagnosis and drug screening.

The development of a rapid and sensitive detection method for well-known, yet abused, antibiotics has been an important issue for food safety and environmental protection. This paper presents a simple and sensitive method for the specific or family-selective detection of antibiotics using carbon nanotube (CNT)-based sensors. Herein, CNT-based sensor transducers were functionalized with the single-chain variable-fragment (scFv) of antibodies that can selectively bind to a specific antibiotic or the certain family of antibiotics. Our CNT-based sensors functionalized with A2 scFv or F9 scFv exhibited the specific detection of enrofloxacin or the family-selective detection of fluoroquinolone-based antibiotics, respectively, in a real-time manner. This simple but efficient strategy can be utilized for various applications in the fields of food safety and environmental protection.

We report a successful development of a floating electrode-based DNA sensor with controllable responses. Here, metallic floating electrodes were fabricated to form Schottky barriers between carbon nanotubes and the floating electrodes. We showed that the sensor response could be enhanced by increasing the number of floating electrodes. We also analyzed the response of the sensors based on the Langmuir isotherm theory.

There have been extensive efforts to improve the properties of conventional metals such as electrical conductivity and rigidity. Here, we report a massive fabrication strategy for metal–carbon nanotube (CNT) laminate-based electrodes. In this method, CNTs were assembled by directed assembly strategy and a thin metal layer was formed by electrodeposition process, and those processes were repeated several times to fabricate multilayered structures. We demonstrated that metal–CNT laminates showed 42% enhancement in the conductivity compared to electrodeposited metals. Furthermore, its Young’s modulus was found to be 88% higher than pure bulk metals. Interestingly, the fabricated structures show I–V characteristics of metal wires while exhibiting typical noise characteristics of CNTs. Since our method uses only conventional microfabrication facilities, it can be readily used by the present microfabrication industry.

We developed a nanoneedle transistor-based sensor (NTS) for the selective detection of calcium ions inside a living cell. In this work, a single-walled carbon nanotube-based field effect transistor (swCNT-FET) was first fabricated at the end of a glass nanopipette and functionalized with Fluo-4-AM probe dye. The selective binding of calcium Ions onto the dye molecules altered the charge state of the dye molecules, resulting in the change of the source-drain current of the swCNT-FET as well as the fluorescence intensity from the dye. We demonstrated the electrical and fluorescence detection of the concentration change of intracellular calcium ions inside a HeLa cell using the NTS.

The aligned assembly of carbon nanotubes (CNTs) on substrate presents a significant bottleneck in the fabrication of high-performance thin film devices. Here, we report a direct printing method to prepare laterally aligned thick CNT patterns over large surface regions. In this method, CNT forests were grown selectively on specific regions of one substrate, and the forest patterns were transferred on another SiO(2) substrate in a laterally aligned formation while keeping their original shapes. The degree of alignment was characterized via electrical measurement and polarized Raman spectroscopy. Furthermore, we demonstrated high-performance field-effect transistors and gas sensors using our method.

We report a direct deposition strategy for sub-50-nm-scale uniform Au patterns on virtually any general insulating substrate via dip-pen nanolithography (DPN). In that process, HAuCl(4) molecules were deposited onto bare insulating substrates via a molecular diffusion process, in the absence of electrochemical reactions. Subsequently, the generated HAuCl(4) molecular patterns were decomposed to leave Au-only patterns using a thermal annealing process. Uniform Au patterns with a mean diameter of 47.9 +/- 3.1 nm were achieved after the annealing process. The strategy allowed us to generate Au patterns on virtually any general insulating substrate (e.g., SiO(2), Al(2)O(3), polyimide, etc) without the need for surface functionalization or additional electrode structures. This versatile and reliable patterning method is expected to be useful in the future development of various novel industrial applications (e.g., mask or nanocircuit repair, nanosensors, etc.).