bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Oxygen-atom Functionalization of Hydrocarbons at Carbon Electrodes
Authors: Manthiram Karthish
Published: May 2020

Oxygen-atom functionalization of chemical intermediates is critical for the production of diverse textiles, plastics, and pharmaceuticals, including epoxides and ketones. The wet chemical and thermochemical routes used today suffer from large carbon dioxide footprints, stoichiometric waste products, and hazardous reagents. We have developed a route whereby water can be used as the oxygen atom source in functionalization reactions of hydrocarbons. At the cathode, hydrogen is selectively generated. Overall, this reaction provides a means by which the oxidizing equivalents can go towards generating a valuable product rather than generating oxygen which is simply vented in a conventional water electrolyzer. We have developed mechanistic understanding of how water is oxidized, providing means by which the selectivity for oxygen-atom functionalization can be rationally improved.
Microporous Carbon Electrodes Derived from Polyacrylonitrile/Poly(Styrene-co-Acrylonitrile) Blends
Authors: Garcia Juan Alexandro , Perananthan Sahila , Balkus Kenneth J. , Ferraris John P.
Published: May 2020

Current energy demands and technological advancements will require a wide array of energy storage devices such as supercapcitors that can deliver large quantities of energy quickly. Electrochemical double layer capacitors (EDLC) are capable of cycling thousands of times with minimal drop in total capacitance, and when used with an ionic liquid electrolyte they can deliver higher energy densities due to high operating voltages. Surface area, and pore size distribution play a critical role in the performance of EDLC devices due to their relationship to capacitance. Therefore, electrospun carbon nanofibers are a promising EDLC electrode material due to their high surface area, conductivity, and cyclability. Their surface area can be tailored with the inclusion of in-situ porogens in the polymer precursor and activation during carbonization. Polymer derived carbon fibers have been produced from polyacrylonitrile (PAN) using immiscible blends with sacrificial polymers like polystyrene (PS). The resulting carbons have high surface areas (>2,000 m2g-1), but a wide distribution of pore sizes. Altering the miscibility of the sacrificial polymer with the copolymer poly(styrene-co-acrylonitrile) (SAN) affords a unique fiber morphology with a high microporosity.

Figure 1
Machine Learning for Molecular Perceptron: A Perception-Based Sensing System
Authors: Yang Yoona , Yaari Zvi A , Settle Alex , Heller Daniel A. , Zheng Ming , Jagota Anand
Published: May 2020

Single wall carbon nanotube (SWCNT) based biosensors provide opportunities for building an ultra-sensitive biosensing system due to their unique optical properties and strong sensitivity to changes in the local environment. Consequently, much effort has been made to develop SWCNT-based sensors. However, the usual method is based on one-to-one recognition which is a difficult way to detect various molecules since it requires the same number of highly specific receptors as the number of molecules one wishes to detect. To detect a combination of various analytes simultaneously, an effective and automatic data processing system is essential. In this study, we propose a new perception-based sensing system using weakly-specific sensor arrays that can be analyzed by an artificial perception model, which we call the Molecular Perceptron. We show how machine learning algorithms along with choice of feature representation is designed to predict presence and concentration of biomarkers or direct prediction of disease states. For example, we demonstrate that the Molecular Perceptron can detect Human epididymis protein 4 (HE4) in the presence or absence of other analytes; HE4 is one of two FDA-approved serum biomarkers for ovarian cancer which provides noticeable sensitivity and specificity for ovarian cancer diagnosis. DNA/SWCNT hybrids were utilized to optically detect the analytes by observing changes in the fluorescence spectra of each SWCNT. Using the experimental data, machine learning models were trained using three different algorithms: Support Vector Machine, Random Forest, and Artificial Neural Network. The models were then validated using new experimental data for different analyte concentrations. Overall, the machine learning models successfully predict the presence of HE4 at the concentrations of 10 nM or higher by giving F1-scores of ~0.85. This is strongly suggestive of the idea that the perception mode of sensing can make accurate judgements in a noisy sensing environment.
(Invited) Polymer Functionalized Nanocarbons for Biomedical Applications
Authors: Budhathoki-Uprety Januka , Chen Yu , Drago Julia , Godthi Nidhi
Published: May 2020

Nanocarbons such as photoluminescent single-walled carbon nanotubes are promising materials in biomedical field as molecular imaging agents, optical probes and biosensors. However, these carbon-only nanomaterials lack active surface functional moieties to interact effectively with select biomolecules of interest, which limits their potential applications. Tailored surface functionalization is essential for anticipated functions and bio-compatibility. Polymer adsorption on nanocarbons through multivalent interactions provides a versatile platform to develop functional materials with tunable surface chemistry. Herein, we investigate on biomimetic polymer scaffolds for carbon nanotubes to modulate their physiochemical properties and bio-molecular interactions.
Monitoring Plant Health with Near Infrared Fluorescent H2O2 Nanosensors
Authors: Wu Honghong , Nißler Robert , Morris Victoria , Herrmann Niklas , Hu Peiguang , Kruss Sebastian , Giraldo Juan Pablo
Published: May 2020

Nanotechnology-based sensors are promising tools for optimizing plant performance and use of resources in agriculture by equipping plants with capabilities to report when they are under stress and require intervention. Herein, we interfaced near infrared (nIR) fluorescent nanosensors with plant leaves that report hydrogen peroxide (H2O2), a key signaling molecule associated with the onset of plant environmental and pathogen stresses. For this purpose, we used single-walled carbon nanotubes (SWCNT) as non-photobleaching fluorescent building blocks for H2O2 nanoscale sensors with a nIR fluorescent emission (> 800 nm) in a ultra-low background region that is ideal for high-sensitivity remote sensing and imaging. SWCNTs were functionalized with a DNA aptamer that binds to hemin, resulting in nIR fluorescence nanosensor response that is quenched by H2O2 in a dose dependent way within the plant physiological range (10-100 H2O2 µM). The in vivo sensor sensitivity for H2O2 (10 µM) allows it to reversibly report signs of stress in plants exposed to UV-B, high light, and a microbial pathogen related peptide (flg 22), but not mechanical leaf wounding. The sensor response was imaged in leaves by a standoff nIR camera, which reported remotely changes in sensor nIR emission up on stress. Such nanotechnology-based sensors report plant signaling molecules associated with early signs of stress and will impact our understanding of plant stress communication, provide novel tools for precision agriculture, and reduce undesirable losses of agrochemicals in the environment.
The Impact of Covalent Functionalization on Single-Walled Carbon Nanotube Biosensor Fluorescence and Function
Authors: Chio Linda , Pinals Rebecca L , Goh Natalie , Murali Aishwarya , Landry Markita P
Published: May 2020

Single-walled carbon nanotubes (SWCNTs) are advantageous signal transduction elements for biological imaging and sensing due to their notable fluorescence in the near-infrared (NIR) region with minimal light absorbance by water or scattering by tissue (1). Recently, exciting developments in SWCNT surface chemistry have shown the retention and improvement of fluorescence intensity in SWCNTs after covalent surface functionalization (2). These chemistries provide chemical handles for specific attachment of molecules of interest to the SWCNT surface while keeping the intrinsic SWCNT NIR fluorescence intact for bioimaging and sensing applications. However, despite their unperturbed fluorescence, it is unclear whether functionalized SWCNTs maintain their ability for molecular sensing, which necessitates a modulation in SWCNT fluorescence provided by the molecular recognition of a noncovalently surface-adsorbed polymer. We compare the photophysical properties of functionalized SWCNTs to their pristine counterparts, and show SWCNT optical properties remain available for sensing applications, however with noted attenuation of fluorescence modulation between certain surface coating and analyte pairs. Molecular recognition provided by phospholipid SWCNT surface coatings maintain their ability to detect molecular analytes such as fibrinogen and insulin. Conversely, DNA oligonucleotide surface coatings under-perform for molecular recognition of dopamine compared to sensors constructed from pristine SWCNTs. We also discuss the use of covalent handles to tune the intrinsic properties of the SWCNT surface for use as biological tools. Lastly, we explore the application of covalently functionalized SWCNTs as dual-functional nanoparticles with both targeting and sensing capabilities. Our work establishes the potential advantages and drawbacks of covalent SWCNT functionalization, despite preservation of SWCNT fluorescence, and implications for applications in molecular sensing.

(1) Bonis-O’Donnell, J. T. D.; Page, R. H.; Beyene, A. G.; Tindall, E. G.; McFarlane, I. R.; Landry, M. P. Dual Near-Infrared Two-Photon Microscopy for Deep-Tissue Dopamine Nanosensor Imaging. Adv. Funct. Mater.
2017, 27 (39), 1–10.

(2) Setaro, A.; Adeli, M.; Glaeske, M.; Przyrembel, D.; Bisswanger, T.; Gordeev, G.; Maschietto, F.; Faghani, A.; Paulus, B.; Weinelt, M.; et al. Preserving π-Conjugation in Covalently Functionalized Carbon Nanotubes for Optoelectronic Applications. Nat. Commun.
2017, 8, 1–7.
What Can We Learn from Carbon Nanotube Diffusion Trajectories Recorded in the Live Brain?
Authors: Lee Antony , Danné Noémie , Paviolo Chiara , Soria Federico , Ferreira Joana S , Bezard Erwan , Groc Laurent , Cognet Laurent
Published: May 2020

Luminescent single wall carbon nanotubes are now well established, as unique nanoreporters to probe the brain extracellular space[1-3]. On the imaging side, this comes from their rich near-infrared optical properties, which also eventually be improved by sp3-chemical functionalization. In addition, their uncommon 1D morphology is an important asset for tissue penetration, yet understanding their diffusion behavior in the complex brain extracellular network is challenging and necessitates dedicated analysis tools. To this aim, we propose novel approaches (i) based on the local analysis of trajectory contours to locally measure the nanoscale dimensions of the brain network [4] and (ii) based on the transient evaluation of carbon nanotube mean square displacement to delineate the ECS molecular diffusion landscape [5]. The application of these analytical tools to extract relevant biological parameters in physiological and pathological brain models will be presented [6].

References

[1] Godin et al Nat. Nanotechnol. 12 (2017) 238-243.

[2] Gao, et al, Nanomaterials 7, 11, (2017) 393.

[3] Danné et al ACS Photonics, 5, 2, (2018) 359-364

[4] Paviolo et al Methods (2019) in press

[5] in preparation

[6] Soria et al in revision
(Invited) Development of a Single Walled Carbon Nanotube Sensor for Long Term Implantation and Detection in a Large Animal Model
Authors: Iverson Nicole M , Hofferber Eric M , Meier Jakob , Herrera Nicolas , Calkins Chris , Kachman Stephen D
Published: May 2020

Fluorescent sensors are frequently not used for in vivo research due to photobleaching and difficulty in signal detection. Single walled carbon nanotubes (SWNT) circumvent these issues with near infrared fluorescent emission and long term stability; yet detection of carbon nanotube sensors has never before been performed in large animal models. The ability to place and read SWNT sensors in vivo for a large animal requires specialized instrumentation and research facilities. By teaming up with large animal veterinarians and meat scientists, our lab was able to surgically place, monitor, and recover SWNT sensors from 14 sheep. We examined various SWNT platforms, implantation locations, and detection methods to determine a strategy for frequent, consistent detection of SWNT sensors that serve as an indicator of animal stress and overall health.
(Invited) Evolution of Synthetic Molecular Recognition on Single Walled Carbon Nanotubes
Authors: Landry Markita P
Published: May 2020

Molecular recognition is fundamental to the design of therapeutics, diagnostics, and sensors. Many of these sensor technologies rely on natural or synthetic molecular recognition elements such as antibodies and aptamers, which have evolved to be highly selective for their molecular targets. However, there are numerous applications for which existing approaches to molecular recognition have been unable to generate optical probes, particularly for neuromodulators and neuropeptides. Herein, we describe a polymer evolution-based platform, in which 10^12 unique polynucleotide polymers are adsorbed to single-walled carbon nanotubes (SWNT). The SWNT-pinned polynucleotide polymers can be screened for their ability to bind a target analyte and provide a selective near-infrared fluorescence signal. Iterative selection of analyte-binding polymers that form a SWNT-surface-adsorbed phase for target recognition are identified through ionic desorption of sub-optimal polymers, and exponential amplification of synthetic polymers that recognize the target analyte. Next-generation sequencing identifies SWNT-polynucleotide conjugates with sequences selective and sensitive for the desired analyte. We demonstrate the utility of this platform for the evolution of SWNT-polymer nanosensors for neuromodulators [1] and neuropeptides, and discuss its potential for identification of chirality-specific SWNT separation. Our results suggest our platform is fundamentally generic in enabling the evolution of nanosensors from synthetic polymer-nanoparticle conjugates for any desired analyte.

1. Jeong, S., Yang, D., Beyene, A.G., O’Donnell, J.T.D., Gest, A. M., Navarro, N., Sun, X., Landry, M.P. High Throughput Evolution of Near Infrared Serotonin Nanosensors. Science Advances (2019). DOI: 10.1101/673152
Organic Color Center Photoluminescence Modulation for Biomedical Applications
Authors: Kim Mijin , Langenbacher Rachel E , Chen Chen , Frederiksen Rune , Wu Xiaojian , Wang Peng , Luo Hongbin , Wang YuHuang , Heller Daniel A.
Published: May 2020

The modulation of single-walled carbon nanotube (SWCNT) photoluminescence has been under investigation for the unique potential to develop biosensors capable of detecting many classes of analytes. Covalent sp3 defects have introduced emissive color centers on SWCNTs, significantly enhancing photoluminescence quantum yield and chemical selectivity/sensitivity to certain analytes. The application of these organic color centers (OCCs) for biomedical applications requires new methods to both conduct covalent chemistry and to concomitantly control the surface chemistry and the resulting biological interactions/biocompatibility via their supramolecular interactions with polymers and other excipients. We will report specific utilities of OCCs for the detection of chemical phenomena where SWCNT photoluminescence is normally relatively insensitive, such as pH changes in the physiologic range of 4.5 - 8. We have developed OCCs to measure endolysosomal pH in live cells and in vivo, as well as other emerging applications. The results support the feasibility of using OCCs as biosensors for disease detection and biomedical research.
Microplasma Synthesis of Luminescent N-Doped Graphene Quantum Dots for pH Sensing
Authors: Kurniawan Darwin , Chiang Wei-Hung
Published: May 2020

Graphene quantum dots (GQDs), the newest type of carbon nanoparticles (CNPs) with size <20 nm, have attracted many research attentions due to the highly tunable photoluminescence (PL) properties, biocompatibility, chemical and photo stability, and low toxicity. Doping GQDs with heteroatoms, such as nitrogen, can increase the PL quantum yield and has strong electron withdrawing ability. Therefore, nitrogen-doped GQDs as fluorescent pH monitor excels in sensitivity, selectivity, rapidity, and applicability comparing with the conventional electrochemical method, especially for bio-related and medical applications. Good biocompatibility and low toxicity also make N-GQDs more preferable to semiconductor quantum dots, organic fluorescent dyes, and noble-metal nanoparticles. As a matter of fact, pH value plays a very important and crucial role in all life forms. A small variations in pH not only endangers the lives of plants and animal but also human beings as it will mainly pollute our drinking water, which may cause some health issues, like physiological dysfunction or diseases. Furthermore, cancer and tumor cells can also be diagnosed through cellular imaging due to the abnormal pH inside human body.

Most of the approaches for synthesizing N-GQDs are complex, time-consuming, in need of harsh reaction condition, and costly. Hereby, microplasma emerges as one of the most promising approaches for nanomaterials processing due to its facile, stable, efficient, and relatively low cost. The high electron density provided are very energetic (~10eV), which allows non-thermal dissociation of molecular gases to form high concentrations of reactive radical species, e.g. OH˙, O˙, O2
-˙, and NO˙. These reactive radical species along with electrons are brought into the precursor solutions and will interact with the solution chemical species to form GQDs in a cascaded chemical reactions.

Here we report a microplasma synthesis of N-GQDs for pH sensing. N-GQDs with high quantum yield up to 30% have been synthesized via microplasma approach from chitosan. This synthetic method leads to highly crystalline particles with easily tunable properties in high reproducibility from a simple biomass as the sole precursor. Based on protonation and deprotonation of N-GQDs surface functional groups, a PL based pH probe with broad linear range of 1.78-13.56 and high accuracy can be constructed. Moreover, two linear lines relationship between UV absorption and different pH value are also obtained, covering from pH 1.25-10.17 and pH 10.17-13.24. The dual optical sensing characteristics allow for almost covering the entire pH range and better accuracy.

Figure 1
Nanoelectronic Biomolecular Sensors Based on Graphene Field-Effect Transistors for Protein Biomarker Detection
Authors: Bazan Claudia Marcela , Bencherif Amira , Wilhelm Brian T. , Bouilly Delphine
Published: May 2020

Field-effect transistor devices based on functionalized graphene (G-FETs) are a promising technology for biomolecular sensing applications due to the several advantages they present, including the label-free detection of biomolecules with direct electrical read-out, real-time detection and multiplexing capability. The development of highly selective and sensitive sensors for protein biomarkers is especially desirable to open novel technological avenues for the early detection and monitoring of biomarkers associated with cancer diseases. In this presentation, I’ll describe our recent progress on the design and development of a label-free immunosensor based on antibody-modified graphene field-effect transistors for protein biomarker detection. Specifically, monoclonal antibodies were selected to target a protein biomarker specific to MLL translocated acute myeloid leukemia and we tested approaches for their immobilization on graphene. We found that the antibodies can spontaneously adhere to the graphene surface but this adhesion is partially reversible under solution flow. In order to stabilize the immobilization of antibodies, we developed a protocol based on electrochemically-driven chemistry to form stable covalent anchor groups at the graphene surface which can then capture antibodies. We optimized the rate of formation of anchor groups at the surface in order to maximize the density of anchor groups while maintaining high electrical currents in the graphene. We were then able to record a specific electrical signature showing irreversible immobilization of antibodies on the graphene surface, thus allowing further optimization of target detection. Employing a combination of microfluidics and real-time electrical measurements, we then investigated the response of the sensors to non-specific interactions with graphene as well as their response to specific antibody-antigen interactions in phosphate buffer solution. Finally, the sensors response to different concentrations of target protein was characterized to assess their performance parameters.
Fluorescent Carbon Nanostructures: Biological Studies
Authors: DaRos Tatiana
Published: May 2020

The interest in application of carbon nanostructures for theranostics is growing, considering the importance this approach is assuming, as well as personalized medicine and nanomedicine.

The family of carbon nanostructures presents some components which are intrinsically fluorescent while in other case the functionalization with well-known tags, among which fluorescein, can supply to the lack of this properties. In this contribution we will explore some biological studies of materials belonging to the two classes of nanostructures.
Single-Wall Carbon Nanotube Uptake Based on Energy-Dependence and Metastatic Potential of Epithelial Cells Motivates Carrier Delivery of Drugs for Targeting Cancer
Authors: Jin Sumin , Dahl Kris Noel , Islam Mohammad F.
Published: May 2020

Cancer cells have altered metabolic activity that can be appropriated for delivery of drugs. Rapidly proliferating cancer cells internalize a high amount of protein-dispersed single-wall carbon nanotubes (SWCNTs) with increased endocytosis from deprivation of metabolic fuels, overexpression and increased recycling of membrane receptors, and mechanosensitivity. Differential uptake of protein-dispersed SWCNTs in various cell types have been reported previously, demonstrating that SWCNT uptake highly depends on uptake pathway and cell metabolism. However, there is still gap in understanding how metastatic potential and cell metabolism can differentiate SWCNT uptake and delivery of drugs in a type of cells. In this work, we present uptake and efficacy of SWCNTs/drug/protein complexes in three different epithelial cell lines, NRK-52E, HeLa, and Hs 578T, that present different metabolic levels from their metastatic potentials. We first create SWCNTs/drug/protein complexes with doxorubicin, a common model cancer drug, and bovine serum albumin (BSA), a model protein that has been extensively studied with SWCNT, using a previously developed unique drug loading system using stepwise assembly on SWCNT networks. The result presented that the cells takes up SWCNTs differently in accordance to their metabolic activity, where Hs 578T cells, with the highest metastatic potential and metabolism, take up ~ 10× more nanotubes compared to an epithelial monolayer of NRK-52E cells. Extent of reduction in cell viability from the delivered drugs were in line with the amount of SWCNT uptake. Our work provides further understanding of differential uptake of protein-dispersed SWCNTs with respect to metabolism and energy requirement of the cells. This suggests that protein-dispersed SWCNTs could preferentially target and deliver drugs to cancer cells in a local area with a combination of normal epithelial cells and cancerous cells.
Length-Dependent Uptake, Inflammation, and Intracellular Processing of Single-Wall Carbon Nanotubes in Macrophages
Authors: Jin Sumin , Wijesekara Piyumi , Boyer Patrick D. , Dahl Kris Noel , Islam Mohammad F.
Published: May 2020

Understanding the impact of single-wall carbon nanotube (SWCNT) lengths on cytotoxicity, uptake and intracellular processing is essential in realizing SWCNT-based drug delivery systems. In addition, cell type-specific response to SWCNT cannot be neglected since SWCNT uptake and processing vary across different cell types. Immune cell-specific processing of SWCNTs in different lengths is of particular interest because immune cells are capable of two distinct size-dependent cellular entry pathways; endocytosis and phagocytosis, and they engage in various physiological conditions such as wound healing, inflammation, and cancer. In this work, we present the impact of SWCNT lengths on uptake, inflammation, and intracellular processing of SWCNTs in macrophages. SWCNTs with average lengths of 50 nm (ultra-short), 145 nm (short), and 500 nm (long) were noncovalently dispersed with bovine serum albumin (BSA), which promotes cellular uptake without affecting cell viability. Interestingly, the amount of uptake was significantly higher for ultra-short SWCNTs compared to longer nanotubes. Moreover, short-SWCNTs became highly bundled in macrophages, which were mostly retained for at least 24 h. In contrast, most long- and ultra-short- SWCNTs remained individualized inside macrophages and were eventually exocytosed over time. Further, we observed pro-inflammatory behavior of macrophage upon exposure to ultra-short-SWCNTs. Overall, the length-dependent inflammation and intracellular processing in macrophages allow for tailoring SWCNT properties for biomedical therapy and imaging. High internalization and subsequent exocytosis of ultra-short-SWCNTs and the triggered pro-inflammatory behavior are more preferred for cancer therapy and drug delivery, while high retention of short-SWCNTs in macrophages could be more desirable for biomedical imaging and macrophage tracking in vivo.
(Invited) In Situ Study on Cleation and Growth of Single-Walled Carbon Nanotubes on Catalysts
Authors: Yang Feng , Li Yan
Published: May 2020

Understanding the growth mechanism is prerequisite to design the methodology for controlled growth of single-walled carbon nanotubes (SWNTs). By using an environmental aberration-corrected transmission electron microscope in combination with in situ synchrotron X-ray absorption spectroscopy, we directly present the structural and composition evolution of cobalt and cobalt-tungsten intermetallic catalysts during the nucleation and growth of SWCNTs under carbon feeding. The co-existence of cobalt and cobalt carbide was generally observed among the pure cobalt catalysts which are active in nucleating tubes. The nucleation and growth behaviors of tubes on solid state cobalt nanoparticles and molten ones have been compared. It was found that the tubes grown from solid state catalysts always present smaller diameter than the catalysts. No structure-correlation between catalyst and nanotube was found. Distinct different from cobalt, no carbides or carbon diffusion induced structural change was observed from the in situ characterization. The atomic structure of Co7W6 was stable when CNTs nucleating. These observations reveal that cobalt-tungsten intermetallic catalysts act as the stable structure template for the chirality controlled growth of SWNTs.
Simultaneous and Individual Determination of Six Redox-Active Biomolecules Using a Modified Graphite Paste Electrode with Immobilized Ferric Cyanide-Chitosan Polymer Ion Pair on the Multi-Walled Carbon Nanotubes
Authors: Li Shaopei , Noroozifar Meissam , Kerman Kagan
Published: May 2020

Redox-active biomolecules such as Ascorbic acid (AA), Dopamine (DA), Uric acid (UA), Tryptophan (Trp), Xanthine (XA), and Caffeine (CA) are all critical for biological homeostatic maintenance. The depletion or over consumption in any of the biomolecules can lead to detrimental effects. For example, previous reports have suggested the depletion of dopamine in the brain is highly correlated to the progression of Parkinson’s disease 1. Caffeine, though not a bio-molecules, it is frequently consumed, and overdose can lead to neurological damage, or even death 2,3. In extension, these bio-molecules tend to exists as a mixture. Thus, it becomes important to develop a platform that enables the monitoring of these biomolecule concentrations simultaneously.

In recent years, carbon nanotubes have collected a great amount of attention from the electrochemical sensor development communities 4. Due to their high surface to volume ratio, carbon nanotubes are able to enhance the electrical catalytic activity increasing the overall conductance 5. This characteristic is highly essential as not only it can increase the potential application range, it can also resolve and separate for biomolecules that have overlapping redox-potentials. In addition, nanotubes are highly biocompatible and do not pose a toxic effect on the biological system. In this work, a novel immobilized ferric cyanide-chitosan polymer ion pair on the multi-walled carbon nanotube-based nanocomposite was synthesized and utilized for the construction of a sensor platform capable of simultaneously detecting six redox-active biomolecules.

Using Fourier-transform infrared spectroscopy, and scanning electron microscopy, the nanocomposite was shown to be successfully synthesized. Cyclic voltammetry, and electrochemical impedance spectroscopy both demonstrated the final modified electrode has improved electrochemical activity. Using differential pulse voltammetry, AA, DA, UA, Trp, XA, and CA were all detected simultaneously (Shown in Figure 1). Finally, the sensor performance was analyzed in real samples and demonstrated a comparable performance. These results demonstrated the reported sensor has a strong potential to become the next generation of biosensors.

Reference

1. A. Nobili et al., Nat. Commun., 8, 14727 (2017).

2. J. W. Daly, Cell. Mol. Life Sci., 64, 2153–2169 (2007).

3. B. J. Gurley, S. C. Steelman, and S. L. Thomas, Clin. Ther., 37, 275–301 (2015).

4. J. Wang, Electroanalysis, 17, 7–14 (2005).

5. A. Eatemadi et al., Nanoscale Res. Lett., 9, 1–13 (2014).

Figure 1
Templating Colloidal Sieves for Tuning Nanotube Surface Interactions and Optical Sensor Responses
Authors: Gillen Alice Judith , Siefman Daniel Jerome , Wu Shang-Jung , Bourmaud Claire , Lambert Benjamin Paul , Boghossian Ardemis Anoush
Published: May 2020

Surfactants offer a tunable approach for modulating the exposed surface area of a nanoparticle. They further present a scalable and cost-effective means for suspending single-walled carbon nanotubes (SWCNTs), which have demonstrated practical use as fluorescence sensors. Though surfactant suspensions show record quantum yields for SWCNTs in aqueous solutions, they lack the selectivity that is vital for optical sensing. We present a new method for controlling the selectivity of optical SWCNT sensors through colloidal templating of the exposed surface area. Colloidal nanotube sensors were obtained using various concentrations of sodium cholate, and their performances were compared to DNA-SWCNT optical sensors. Sensor responses were recorded against a library of bioanalytes, including neurotransmitters, amino acids, and sugars. We report an intensity response towards dopamine and serotonin for all sodium cholate-suspended SWCNT concentrations. We further identify a selective, 14.1 nm and 10.3 nm wavelength red-shifting response to serotonin for SWCNTs suspended in 1.5 and 0.5 mM sodium cholate, respectively. Through controlled, adsorption-based tuning of the nanotube surface, this study demonstrates the applicability of sub-critical colloidal suspensions to achieve selectivities exceed- ing those previously reported for DNA-SWCNT sensors.
Biomedical Application Via Implantable Devices By CMOS-Compatible Glucose Fuel Cells Using Carbon Nano Horn
Authors: Islam Md. Zahidul , Arata Shigeki , Hayashi Kenya , Kobayashi Atsuki , Niitsu Kiichi
Published: May 2020

Solid-state complementary metal oxide semiconductor (CMOS)-compatible glucose fuel cells, with carbon nano horn (CNH) films with different amounts of CNH (wt.%) and glucose solution were investigated. CNH content of 3 wt.% with 30 mM glucose solution was found the highest open circuit voltage (OCV) of 420 mV, a power density of 2.83 µW/cm2 and current density of 6.73 µA/cm2. This is the highest value compared with the conventional glucose fuel cell. The OCV and power density increased together with the fuel cell concentration. The developed fuel cell uses materials that are bio-compatible with the human body (CNH-glucose). As a result, OCV of 420 mV with a CNH content of 3 wt.% while improvements in the performance of the CMOS-compatible fuel cell were obtained, and the parameters affecting the performance of the fuel cell were identified. This glucose fuel cell was fabricated using CMOS semiconductor processes on a silicon wafer. This work presents a (5 mm × 5 mm) solid-state CMOS compatible glucose fuel cell that 420 mV of OCV. It is the highest value for a glucose fuel cell when the anode area is (4.2 mm × 4.6 mm). These findings are significant in realizing mobile or implantable devices that can be used for biomedical applications.
Interfacing Copper and Carbon Nanotubes with Titanium for Enhanced Electrical Performance
Authors: McIntyre Dylan J. , Hirschman Ryan , Puchades Ivan , Landi Brian J.
Published: May 2020

Hybrid Cu-carbon nanotube (CNT) conductors provide high electrical conductivities, while benefiting from the low temperature coefficient of resistance for CNTs. However, the poor interaction between Cu and CNTs requires a method of interfacing the components to improve the connectivity of the Cu-CNT conductor while preserving the electrical properties. Herein, Ti and Ni were evaluated as interfacial metals by thermally evaporating 10 nm layers onto a CNT conductor to assess the nanoscale morphology and impact on temperature dependent electrical properties. SEM analysis shows Ni deposits onto the CNT surface as a continuous layer in the form of discrete nanoscale crystallites. In contrast, Ti deposits a uniform layer along the surface of the CNT network. The Ni crystallites coalesce from the initially continuous layer upon exposure to temperatures up to 400 °C, while Ti is shown to remain as a stable uniform coating on the CNTs over such temperatures. Subsequent deposition of a 100 nm Cu layer onto CNT, Ti-CNT, and Ni-CNT conductors was performed to measure electrical stability with increasing annealing temperature. The 100 nm Cu layer forms gaps as it delaminates from the CNTs after exposure to 400 °C in a H2/Ar anneal when no adhesion metal is present, and the resistance per length (R/L) increases by 40%. The gaps formed in the Cu layer by the 400 °C anneal expose underlying CNTs, indicating poor surface interaction. The Cu-Ni-CNT conductor maintains Cu layer integrity from the adhesion metal, but exhibits a 125% increase in R/L for similar annealing conditions. In comparison, Ti sustains favorable interaction for the metal layers on CNTs, and achieves a 12% reduction in R/L after exposure to 400 °C. Temperature dependent electrical measurements performed under vacuum confirm the permanent change in electrical properties at elevated temperature for the hybrid conductors with an adhesion metal, demonstrating the increase in R/L for the Cu-Ni-CNTs and a decrease in R/L for Cu-Ti-CNT conductors. Thus, Ti emerges as an effective adhesion metal for use in metal-CNT conductor operation at elevated temperatures, demonstrating sustained adhesion up to 400 °C, and improvement in electrical properties for Cu-Ti-CNT conductors. Transitioning to scalable systems for integrated CNT conductors, a chemical vapor deposition (CVD) technique will be investigated as a delivery route for improved penetration of Ti into the CNT network.
Stimuli-Responsive Molecule Modification to Locally Functionalized Single-Walled Carbon Nanotubes for Wavelength Switching of Near Infrared Photoluminescence
Authors: Shiraki Tomohiro , Nakagawa Yasuto , Nakashima Naotoshi , Fujigaya Tsuyohiko
Published: May 2020

Single-walled carbon nanotubes (SWNTs) with semiconducting features show near infrared (NIR) photoluminescence (PL). Defect doping to the SWNTs has been found to enhance the PL properties, which is achieved by local chemical modification.[1-9] It allows us to functionalize various molecules on the doped sites and such locally functionalized SWNTs (lf-SWNTs) show PL property changes depending on the modified molecules. For example; electronic property difference in the modified aryl groups induced PL shifts.[3] Moreover, protonation of amine groups[6] and molecular recognition at the doped sites[7,8] can be used for wavelength tuning. Therefore, stimuli responsiveness in the NIR PL properties could be designed in the lf-SWNTs through molecular approaches. In this presentation, we report reversible wavelength modulation based on molecular structure changes occurring at the doped sites by external stimuli. Molecular binding through covalent bond formation and photo-induced structural changes are used for the wavelength switching processes.

Imine chemistry is based on a condensation reaction of aldehyde and amine groups that occurs just by mixing the corresponding compounds. Owing to the reversibility of this reaction system, multistep wavelength switching of the NIR PL was conducted by imine bond formation, exchange or dissociation reactions of the imine bond, and Kabachnik-Fields reactions at the doped sites of the lf-SWNTs.[9] Photo-induced switching of the NIR PL was performed by creating the doped sites functionalized with photochromic molecules that showed color changes (= electronic property changes) by light irradiation. The photo-induced reversible structural changes of the modified molecules on the lf-SWNTs were observed by absorption spectroscopy, which accompanies spectral shifts of the NIR PL of the lf-SWNTs. Details including the relationship between PL shifts and molecular structure changes will be discussed at the meeting.

[1] B. Weisman et al. Science, 330, 1656 (2010). [2] Y. Miyauchi et al. Nat. Photon., 7, 715 (2013). [3] Y. Wang et al. Nat. Chem., 5, 840 (2013). [4] S. Doorn et al. Nat. Photon., 11, 577 (2017). [5] T. Shiraki et al. Sci. Rep., 6, 28393 (2016). [6] Y. Wang et al. J. Phys. Chem. C, 119, 3733 (2015) [7] T. Shiraki et al. Chem. Commun., 52, 12972 (2016). [8] T. Shiraki et al. Chem. Eur. J., 24, 9393 (2018). [9] T. Shiraki et al. Chem. Eur. J., 24, 19162 (2018).

Figure 1
Nanomachining of Carbon Nanotubes to Carbon Nanoribbons
Authors: Das Suprem R.
Published: May 2020

Carbon Nanotubes (CNTs) have revolutionized number of scientific fields such as electronics, composites and biomedical engineering. However, our current ability to manipulate nanotube geometry is limited to only in the in-situ growth reactors. Expanding the knowledge of manipulating materials at nanoscale, such as the CNTs with alternate techniques, will significantly increase their potential for applications such as sensors and as well as bring new physical phenomena. Alternatively, graphene has its numerous success in last nineteen years except being a serious candidate for field effect applications. Nanomachining carbon nanotubes, which may produce altering structural and thus electronic properties, has not been well developed especially in the context of chemical free methods. We are exploiting ultrafast laser matter interactions at Kansas State University to nanomachining CNTs to produce carbon nanoribbons (CNRs) of sub-20 nanometer width and understand their properties. Laser micromachining has numerous applications for current and future technology developments, including those in aerospace and biomedical applications. Such a method to turn CNTs to CNRs will have future electronic and photonic applications.

This work is supported by U.S. National Science Foundation (NSF), funding from Kansas State University and David and Lynda Dawson Carl and Mary Ice Keystone Research funding.
(Invited) Resonant Electroluminescence from Suspended Carbon Nanotube pn-junctions
Authors: Cronin Stephen B.
Published: May 2020

There are various mechanisms of light emission in carbon nanotubes (CNTs), which give rise to a wide range of spectral characteristics that provide important information regarding the underlying physical processes of photon emission. Here, we report resonant electroluminescence in suspended carbon nanotube pn-junctions generated from dual gate CNT field effect transistor (FET) devices. By applying equal and opposite voltages to the gate electrodes (i.e., Vg1 = -Vg2), we create a pn-junction within the CNT. Under these gating conditions, we observe a sharp resonance in the electroluminescence intensity around zero applied gate voltages, where the depletion region in the p-i-n device has the largest spatial extent. Here, the emission occurs under high electrical power densities around 0.1MW/cm2 (or 6µW) and arises from thermal emission at elevated temperatures above 1000K. It is somewhat surprising that this thermal emission intensity is so sensitive to the gating conditions, and we observe a resonant enhancement factor of 1000-fold between Vg1=0V and Vg1=15V, over a range in which the electrical power dissipated in the nanotube is roughly constant. This resonant behavior is understood on the basis of two phenomena that occur when the depletion region is aligned with the trench across which the nanotube is suspended: 1.) heating is increased in the suspended region because the nanotube is not directly heat sunk to the underlying substrate and 2.) light emission is enhanced in the suspended region due to reduced non-radiative recombination caused by the underlying substrate. Based on the calculated conduction and valence band profiles in the device, we find that the size of the depletion region drops by a factor of 5-10X over the range from |Vg|=0V to 15V. We, therefore, conclude that the light emission intensity is significantly dependent on the length of the depletion region in these CNT devices.
(Invited) DNA-Directed High-Precision Assembly of CNT FETs
Authors: Zhao Mengyu , Chen Yahong , Wang Kexin , Streit Jason , Fagan Jeffrey A. , Tang Jianshi , Zheng Ming , Zhu Zhi , Sun Wei
Published: May 2020

Precise fabrication of semiconducting channel materials into densely-aligned uniformly parallel arrays is one prerequisite to the high-performance ultra-scaled technology nodes, in particular for carbon nanotubes (CNTs). Traditional thin-film-based approaches generally yield CNTs in irregularly-spaced bundles or with wide orientation distribution, and lack a mechanism to effectively eliminate mis-aligned CNTs from the ultra-scaled channel area. Therefore, the averaged pitch value and precision of CNT arrays, the key parameters defining lateral CNT spacing, fail to simultaneously meet all of the patterning requirements for the ultra-scaled technology nodes. Bio-fabrication is promising for patterning CNTls at a resolution beyond the existing lithographic limit. However, impacted by surface charges and sub-micron dimensions of typical bio-templates, current bio-templated electronics exhibit both poor transport performance and array uniformity smaller than 1 micron.

We report precise scaling of inter-CNT pitch using a supramolecular assembly method called Spatially Hindered Integration of Nanowire Electronics (SHINE). Specifically, by using nano-trenches to align CNTs and DNA hybridization to stabilize them in place, we constructed parallel CNT arrays with uniform pitch as small as 10.4 nm, at an assembly yield over 95%. The pitch precision improves on that prepared from conventional thin-film approaches by more than two orders of magnitude. Compared to the lithography-patterned Si channels at 10 nm technology node, SHINE simultaneously provides both 70% smaller averaged pitch value and molecular-scale pitch precision in the channel area. By engineering the interfacial compositions, metal ions and surface charges that are destructive to FET performance have been excluded from the channel area without degrading CNT alignment. Under a source-to-drain voltage of -0.5 V, we demonstrate both transconductance more than 0.6 mS/μm with fast on/off switching. And the key FET performance metrics are improved by more than one order of magnitude than previous bio-templated FETs. Furthermore, we demonstrate centimeter-scale alignment of fixed-width CNT arrays. At the interface of high-performance electronics and bio-molecular self-assembly, precise bio-fabrication could provide ultra-scaled devices or circuits compatible with or sensitive to local biological environments.
(Invited) Increasing the Efficiency of Semiconducting Carbon Nanotube Photoabsorber-Based Photovoltaics
Authors: Arnold Michael S.
Published: May 2020

We have previously demonstrated efficient electron transfer from photoexcited small diameter (< 1 nm) semiconducting carbon nanotubes to C60 fullerene electron acceptors in planar, bilayer heterojunction diode devices, with internal quantum efficiency of 90%. However, the out-of-plane exciton diffusion length in planar nanotube thin films is poor (~ 5 nm), limiting the optical density of nanotube films that can be implemented in these devices, which in turn has limited external quantum efficiency to 50% at the nanotube bandgap and to << 50% off-resonance. Polymer solar cells also face a similar limitation (poor exciton diffusion length) and overcome this problem by blending the polymer and acceptor together into a bulk heterojunction. In this talk, our recent research aimed at addressing this shortcoming will be presented.
(Invited) Progress in Using Carbon Nanotube Spectra for Mechanical Strain Sensing
Authors: Meng Wei , Bachilo Sergei M. , Nagarajaiah Satish , Weisman R. Bruce
Published: May 2020

A characteristic property of semiconducting single-wall carbon nanotubes (SWCNTs) is distinct near-infrared photoluminescence following excitation by visible light. Theory and experiment show that these optical emission peaks shift predictably in wavelength as nanotubes are compressed or stretched along their axis. We are exploiting this effect in a powerful new method intended for measuring mechanical strain in critical infrastructure components such as airframes, pressurized vessels, pipelines, support beams, etc. The method involves applying a dilute dispersion of nanotubes in a polymeric host onto the surface of the specimen to form a sub-micron thick film in which SWCNTs act as strain sensors. This layer is overcoated with a transparent protective top coat such as a polyurethane varnish. Subsequent strains in the substrate are transmitted to the nanotubes by load transfer. The substrate strain magnitude and direction are then measured by illuminating the surface at any point of interest with a small visible laser beam and spectrally analyzing the resulting near-IR nanotube emission. Single-point measurements currently provide strain magnitude resolution of ca. 100 microstrain, strain angle resolution of ca. 5 degrees, and spatial resolution of ca. 50 mm. Each reading takes less than one second, allowing compilation of strain maps from scanned data. In contrast to digital image correlation, which is currently the only commercial non-contact strain technology, the new method can measure strains induced when the specimen is not under observation. It thus has the potential for routine use in industrial structural health monitoring as well as in testing and development laboratories. We will also describe recent progress in adapting the technology to camera-based measurements using spectrally resolved fluorescence imaging.