Advances in the synthesis and scalable manufacturing of single-walled carbon nanotubes (SWCNTs) remain critical to realizing many important commercial applications. Here we review recent breakthroughs in the synthesis of SWCNTs and highlight key ongoing research areas and challenges. A few key applications that capitalize on the properties of SWCNTs are also reviewed with respect to the recent synthesis breakthroughs and ways in which synthesis science can enable advances in these applications. While the primary focus of this review is on the science framework of SWCNT growth, we draw connections to mechanisms underlying the synthesis of other 1D and 2D materials such as boron nitride nanotubes and graphene.

Semiconducting single-wall carbon nanotubes are very promising materials in printed electronics due to their excellent mechanical and electrical property, outstanding printability, and great potential for flexible electronics. Nonetheless, developing scalable and low-cost approaches for manufacturing fully printed high-performance single-wall carbon nanotube thin-film transistors remains a major challenge. Here we report that screen printing, which is a simple, scalable, and cost-effective technique, can be used to produce both rigid and flexible thin-film transistors using separated single-wall carbon nanotubes. Our fully printed top-gated nanotube thin-film transistors on rigid and flexible substrates exhibit decent performance, with mobility up to 7.67 cm2 V(-1) s(-1), on/off ratio of 10(4)∼10(5), minimal hysteresis, and low operation voltage (<10 V). In addition, outstanding mechanical flexibility of printed nanotube thin-film transistors (bent with radius of curvature down to 3 mm) and driving capability for organic light-emitting diode have been demonstrated. Given the high performance of the fully screen-printed single-wall carbon nanotube thin-film transistors, we believe screen printing stands as a low-cost, scalable, and reliable approach to manufacture high-performance nanotube thin-film transistors for application in display electronics. Moreover, this technique may be used to fabricate thin-film transistors based on other materials for large-area flexible macroelectronics, and low-cost display electronics.

The ubiquitously expressed c-Abl protein tyrosine kinase localizes to both the nucleus and cytoplasm. The nuclear form of c-Abl is activated in the cellular response to genotoxic stress. Here we show that cytoplasmic c-Abl is activated by oxidative stress. The results also demonstrate that mitochondrial cytochrome c is released in the cellular response to H 2 O 2 and that this effect is mediated by a c-Abl-dependent mechanism. In concert with these results, we show that H 2 O 2 -induced apoptosis is attenuated in c-Abl-deficient cells. These findings demonstrate that cytoplasmic c-Abl is involved in the apoptotic response of cells to oxidative stress.Normal cellular metabolism is associated with the production of reactive oxygen species (ROS) 1 and, as a consequence, damage to DNA and proteins (1, 2). The generation of ROS is also known to induce apoptosis; however, the molecular mechanisms responsible for ROS-induced apoptosis are unclear. Studies have indicated that ROS induce activation of topoisomerase II-mediated cleavage of chromosomal DNA and thereby apoptosis (3). Other work has suggested that ROSinduced apoptosis is p53-dependent (4, 5) and that p53-induced apoptosis is mediated by . In addition, the p66 shc adaptor protein (5) and the p85 subunit of phosphatidylinositol 3-kinase (PI3K) (4) have been implicated in the apoptotic response to oxidative stress.The nuclear form of the c-Abl tyrosine kinase is activated in the cellular response to genotoxic stress (9). Nuclear c-Abl has been implicated in the apoptotic response to DNA damage by mechanisms in part dependent on p53 and its homolog, p73 (10 -14). c-Abl also functions as an upstream effector of the proapoptotic SAPK/JNK and p38 mitogen activated protein kinase (MAPK) pathways in the genotoxic stress response (9,15,16). Other studies have demonstrated that c-Abl phosphorylates p85 and thereby inhibits PI3K activity in the apoptotic response to DNA damage (17). Additional evidence supporting a role for c-Abl in apoptosis has been provided by the findings that cells deficient in c-Abl or expressing a dominant-negative c-Abl mutant exhibit an attenuated apoptotic response to genotoxic agents (18,19).Recent work has shown that c-Abl phosphorylates protein kinase C (PKC) ␦ in cells treated with H 2 O 2 (20). The present results demonstrate that the cytoplasmic, and not the nuclear, form of c-Abl is activated in the cellular response to H 2 O 2 . We also show that H 2 O 2 induces mitochondrial cytochrome c release and apoptosis by a c-Abl-dependent mechanism. MATERIALS AND METHODSCell Culture-COS7 cells and MEFs derived from wild-type and c-Abl Ϫ/Ϫ mice (21) were cultured in Dulbecco's modified Eagle's medium containing 10% heat-inactivated fetal calf serum, 2 mM L-glutamine, 100 units/ml penicillin, and 100 g/ml streptomycin. DLD1 cells were grown as described (7). Cells were treated with H 2 O 2 (Sigma), 30 mM N-acetyl-L-cysteine (NAC; Sigma), or 10 M cis-platinum (Sigma).Analysis of Kinase Activity-Cell lysates were prepared in lysis buffer (10 mM Tr...

Nanoribbon- and nanowire-based field-effect transistor (FET) biosensors have stimulated a lot of interest. However, most FET biosensors were achieved by using bulky Ag/AgCl electrodes or metal wire gates, which have prevented the biosensors from becoming truly wearable. Here, we demonstrate highly sensitive and conformal InO nanoribbon FET biosensors with a fully integrated on-chip gold side gate, which have been laminated onto various surfaces, such as artificial arms and watches, and have enabled glucose detection in various body fluids, such as sweat and saliva. The shadow-mask-fabricated devices show good electrical performance with gate voltage applied using a gold side gate electrode and through an aqueous electrolyte. The resulting transistors show mobilities of ∼22 cm V s in 0.1× phosphate-buffered saline, a high on-off ratio (10), and good mechanical robustness. With the electrodes functionalized with glucose oxidase, chitosan, and single-walled carbon nanotubes, the glucose sensors show a very wide detection range spanning at least 5 orders of magnitude and a detection limit down to 10 nM. Therefore, our high-performance InO nanoribbon sensing platform has great potential to work as indispensable components for wearable healthcare electronics.

Preparation of chirality-defined single-wall carbon nanotubes (SWCNTs) is the top challenge in the nanotube field. In recent years, great progress has been made toward preparing single-chirality SWCNTs through both direct controlled synthesis and postsynthesis separation approaches. Accordingly, the uses of single-chirality-dominated SWCNTs for various applications have emerged as a new front in nanotube research. In this Review, we review recent progress made in the chirality-controlled synthesis of SWCNTs, including metal-catalyst-free SWCNT cloning by vapor-phase epitaxy elongation of purified single-chirality nanotube seeds, chirality-specific growth of SWCNTs on bimetallic solid alloy catalysts, chirality-controlled synthesis of SWCNTs using bottom-up synthetic strategy from carbonaceous molecular end-cap precursors, etc. Recent major progresses in postsynthesis separation of single-chirality SWCNT species, as well as methods for chirality characterization of SWCNTs, are also highlighted. Moreover, we discuss some examples where single-chirality SWCNTs have shown clear advantages over SWCNTs with broad chirality distributions. We hope this review could inspire more research on the chirality-controlled preparation of SWCNTs and equally important inspire the use of single-chirality SWCNT samples for more fundamental studies and practical applications.

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Semiconducting single-wall carbon nanotubes are ideal semiconductors for printed electronics due to their advantageous electrical and mechanical properties, intrinsic printability in solution, and desirable stability in air. However, fully printed, large-area, high-performance, and flexible carbon nanotube active-matrix backplanes are still difficult to realize for future displays and sensing applications. Here, we report fully screen-printed active-matrix electrochromic displays employing carbon nanotube thin-film transistors. Our fully printed backplane shows high electrical performance with mobility of 3.92 ± 1.08 cm V s, on-off current ratio I/I ∼ 10, and good uniformity. The printed backplane was then monolithically integrated with an array of printed electrochromic pixels, resulting in an entirely screen-printed active-matrix electrochromic display (AMECD) with good switching characteristics, facile manufacturing, and long-term stability. Overall, our fully screen-printed AMECD is promising for the mass production of large-area and low-cost flexible displays for applications such as disposable tags, medical electronics, and smart home appliances.

Summary Flexible sensors are essential for advancing implantable and wearable bioelectronics toward monitoring chemical signals within and on the body. Developing biosensors for monitoring multiple neurotransmitters in real time represents a key in vivo application that will increase understanding of information encoded in brain neurochemical fluxes. Here, arrays of devices having multiple In 2 O 3 nanoribbon field-effect transistors (FETs) were fabricated on 1.4-μm-thick polyethylene terephthalate (PET) substrates using shadow mask patterning techniques. Thin PET-FET devices withstood crumpling and bending such that stable transistor performance with high mobility was maintained over >100 bending cycles. Real-time detection of the small-molecule neurotransmitters serotonin and dopamine was achieved by immobilizing recently identified high-affinity nucleic-acid aptamers on individual In 2 O 3 nanoribbon devices. Limits of detection were 10 fM for serotonin and dopamine with detection ranges spanning eight orders of magnitude. Simultaneous sensing of temperature, pH, serotonin, and dopamine enabled integration of physiological and neurochemical data from individual bioelectronic devices.