2D/1D VSe2/MWCNT hybrid-based electrochemical sensor for carbendazim quantification of environmental, food, and biological samples.

For the first time the sensitive determination of carbendatim (CRB) is reported utilizing a well-designed sensing architecture based on vanadium diselenide-multiwalled carbon nanotube (VSMC). FTIR, XRD, FESEM, EDS, and EIS were employed to evaluate the sensor's structural integrity, and the results demonstrated the successful integration of nanomaterials, resulting in a robust and sensitive electrochemical sensor. Cyclic voltammetry (CV) and chronoamperometric (CA) investigations showed that the sensor best performed at pH 8.0 (BRB) with an excellent detection limit of 9.80 nM with a wide linear range of 0.1 to 10.0 µM. A more thermodynamically viable oxidation of CRB was observed at the VSMC/GCE, with a shift of 200 mV in peak potential towards the less positive side compared with the unmodified GCE. In addition, the sensor demonstrated facile heterogeneous electron transfer, favorable anti-fouling traits in the presence of a wide range of interferents, good stability, and reproducible analytical performance. Finally, the developed sensor was validated for real-time quantification of CRB from spiked water, food, and bio-samples, which depicted acceptable recoveries (98.6 to 101.5%) with RSD values between 0.35 and 2.23%. Further, to derive the possible sensing mechanism, the valence orbitals projected density of states (PDOS) for C, H, and N atoms of an isolated CRB molecule, VSe2 + CNT and VSe2 + CNT + CRB were calculated using density functional theory (DFT) calculations. The dominant charge transfer from the valence 2p-orbitals of the C and N atoms of CRB to CNT is responsible for the electrochemical sensing of CRB molecules.

Product Selection Toward High-Value Hydrogen and Bamboo-Shaped Carbon Nanotubes from Plastic Waste by Catalytic Microwave Processing.

The escalating levels of plastic waste and energy crises underscore the urgent need for effective waste-to-energy strategies. This study focused on converting polypropylene wastes into high-value products employing various iron-based catalysts and microwave radiative thermal processing. The Al-Fe catalysts exhibited exceptional performance, achieving a hydrogen utilization efficiency of 97.65% and a yield of 44.07 mmol/g PP. The gas yields increased from 19.99 to 94.21 wt % compared to noncatalytic experiments. Furthermore, this catalytic system produced high-value bamboo-shaped carbon nanotubes that were absent in other catalysts. The mechanism analysis on catalytic properties and product yields highlighted the significance of oxygen vacancies in selecting high-value products through two adsorption pathways. Moreover, the investigation examined the variations in product distribution mechanisms between conventional and microwave pyrolysis, in which microwave conditions resulted in 4 times higher hydrogen yields. The technoeconomic assessment and Monte Carlo risk analysis further compared the disparity. The microwave technique had a remarkable internal rate of return (IRR) of 39%, leading to an income of $577/t of plastic with a short payback period of 2.5 years. This research offered sustainable solutions for the plastic crisis, validating the potential applicability of commercializing the research outcomes in real-world scenarios.

Electrical stimulation of Schwann cells on electrospun hyaluronic acid carbon nanotube fibers.

Neurofibromatosis Type 1 (NF1) is a complex genetic disorder characterized by the development of benign neurofibromas, which can cause significant morbidity in affected individuals. While the molecular mechanisms underlying NF1 pathogenesis have been extensively studied, the development of effective therapeutic strategies remains a challenge. This paper presents the development and validation of a novel biomaterial testing model to enhance our understanding of NF1 pathophysiology, disease mechanisms and evaluate potential therapeutic interventions. Our long-term goal is to develop an invitro model of NF1 to evaluate drug targets. We have developed an in vitro system to test the cellular behavior of NF1 patient derived cells on electroconductive aligned nanofibrous biomaterials with electrical stimulatory cues. We hypothesized that cells cultured on electroconductive biomaterial will undergo morphological changes and variations in cell proliferation that could be further enhanced with the combination of exogenous electrical stimulation (ES). In this study, we developed electrospun Hyaluronic Acid-Carbon Nanotube (HA-CNT) nanofiber scaffolds to mimic the axon's topographical and bioelectrical cues that influence neurofibroma growth and development. The cellular behavior was qualitatively and quantitively analyzed through immunofluorescent stains, Alamar blue assays and ELISA assays. Schwann cells from NF1 patients appear to have lost their ability to respond to electrical stimulation in the development and regeneration range, which was seen through changes in morphology, proliferation and NGF release. Without stimulation, the conductive material enhances NF1 SC behavior. Wild-type SC respond to electrical stimulation with increased cell proliferation and NGF release. Using this system, we can better understand the interaction between axons and SC that lead to tumor formation, homeostasis and regeneration.

Novel electrochemiluminescence sensing platform for ultrasensitive detection of malathion residue in tea based on SiO2NSs doped Luminol/AgNPs as a signal amplification strategy.

To address the potential hazards of organophosphorus pesticides (OPs) residues in tea, an electrochemiluminescence (ECL) aptasensor based on functionalized nanomaterials was constructed in this work. Firstly, gold nanoparticles (AuNPs) were attached on the surface of multi-walled carbon nanotubes (MWCNTs) by the constant potential electrodeposition to form a compound, and it was utilized to provide excellent immobilization sites for complementary DNA (cDNA). Subsequently, composite nanomaterials were synthesized by a one-pot method with aminated Luminol/silver nanoparticles@silica nanospheres (NH2-Luminol/Ag@SiO2NSs). Finally, NH2-Luminol/Ag@SiO2NSs was combined with a malathion aptamer (Apt) to obtain signal probes (SPs) for the construction of an aptasensor. The aptasensor had a wide linear range (1×10-3-1×103 ng/mL) and a low limit of detection (LOD) (0.3×10-3 ng/mL). It had the virtues of high sensitivity, wonderful stability and excellent specificity, which could be used for the detection of malathion residue in tea. The work provides a proven way for the construction of a rapid and ultrasensitive aptasensor with low-cost.

Electronic properties of single vacancy defect in boron nitride nanoribbons with edge perturbation.

Two-dimensional material hexagonal boron nitride (h-BN), and its one-dimensional thin strips, boron nitride nanoribbons (BNNRs) are electrically insulating with high thermal stability, making them excellent thermal conductors suitable for high-temperature application. BNNRs are wide bandgap semiconductors with bandgaps ranging from 4 to 6 eV. This study investigates the electronic properties of BNNRs with single vacancy defects in armchair and zigzag configurations. The nearest-neighbour tight-binding model and numerical method were used to simulate the electronic properties of BNNRs with a single vacancy, including band structure and local density of states. The alpha and beta matrices were adjusted to account for missing boron or nitrogen atoms. Furthermore, a small perturbations were introduced to model the effects of impurities and edge imperfections. The simulation result from this work was compared with pristine BNNRs to examine the impact of a single vacancy on their electronic properties. The findings reveal that both armchair and zigzag BNNRs with single vacancy defects exhibit distorted band structures and local density of states due to the delocalization of pz orbitals. The valence bands show a higher concentration of nitrogen, while the conduction bands are richer in boron. These findings provide insights into how vacancy defects and edge perturbations can influence the electronic properties of BNNRs, which can guide the design and optimization of BNNR-based electronic devices in future research.

Characterizing the Sensing Response of Carbon Nanocomposite-Based Wearable Sensors on Elbow Joint Using an End Point Robot and Virtual Reality.

Physical therapy is often essential for complete recovery after injury. However, a significant population of patients fail to adhere to prescribed exercise regimens. Lack of motivation and inconsistent in-person visits to physical therapy are major contributing factors to suboptimal exercise adherence, slowing the recovery process. With the advancement of virtual reality (VR), researchers have developed remote virtual rehabilitation systems with sensors such as inertial measurement units. A functional garment with an integrated wearable sensor can also be used for real-time sensory feedback in VR-based therapeutic exercise and offers affordable remote rehabilitation to patients. Sensors integrated into wearable garments offer the potential for a quantitative range of motion measurements during VR rehabilitation. In this research, we developed and validated a carbon nanocomposite-coated knit fabric-based sensor worn on a compression sleeve that can be integrated with upper-extremity virtual rehabilitation systems. The sensor was created by coating a commercially available weft knitted fabric consisting of polyester, nylon, and elastane fibers. A thin carbon nanotube composite coating applied to the fibers makes the fabric electrically conductive and functions as a piezoresistive sensor. The nanocomposite sensor, which is soft to the touch and breathable, demonstrated high sensitivity to stretching deformations, with an average gauge factor of ~35 in the warp direction of the fabric sensor. Multiple tests are performed with a Kinarm end point robot to validate the sensor for repeatable response with a change in elbow joint angle. A task was also created in a VR environment and replicated by the Kinarm. The wearable sensor can measure the change in elbow angle with more than 90% accuracy while performing these tasks, and the sensor shows a proportional resistance change with varying joint angles while performing different exercises. The potential use of wearable sensors in at-home virtual therapy/exercise was demonstrated using a Meta Quest 2 VR system with a virtual exercise program to show the potential for at-home measurements.

Multi-walled carbon nanotubes functionalized with a new Schiff base containing phenylboronic acid residues: application to the development of a bienzymatic glucose biosensor using a response surface methodology approach.

An innovative supramolecular architecture is reported for bienzymatic glucose biosensing based on the use of a nanohybrid made of multi-walled carbon nanotubes (MWCNTs) non-covalently functionalized with a Schiff base modified with two phenylboronic acid residues (SB-dBA) as platform for the site-specific immobilization of the glycoproteins glucose oxidase (GOx) and horseradish peroxidase (HRP). The analytical signal was obtained from amperometric experiments at - 0.050 V in the presence of 5.0 × 10-4 M hydroquinone as redox mediator. The concentration of GOx and HRP and the interaction time between the enzymes and the nanohybrid MWCNT-SB-dBA deposited at glassy carbon electrodes (GCEs) were optimized through a central composite design (CCD)/response surface methodology (RSM). The optimal concentrations of GOx and HRP were 3.0 mg mL-1 and 1.50 mg mL-1, respectively, while the optimum interaction time was 3.0 min. The bienzymatic biosensor presented a sensitivity of (24 ± 2) × 102 µA dL mg-1 ((44 ± 4) × 102 µA M-1), a linear range between 0.06 mg dL-1 and 21.6 mg dL-1 (3.1 µM-1.2 mM) (R2 = 0.9991), and detection and quantification limits of 0.02 mg dL-1 (1.0 µM) and 0.06 mg dL-1 (3.1 µM), respectively. The reproducibility for five sensors prepared with the same MWCNT-SB-dBA nanohybrid was 6.3%, while the reproducibility for sensors prepared with five different nanohybrids and five electrodes each was 7.9%. The GCE/MWCNT-SB-dBA/GOx-HRP was successfully used for the quantification of glucose in artificial human urine and commercial human serum samples.

Textile-Based Membraneless Microfluidic Double-Inlet Hybrid Microbial-Enzymatic Biofuel Cell.

This study reports the development of a textile-based colaminar flow hybrid microbial-enzymatic biofuel cell. Shewanella MR-1 was used as a biocatalyst on the anode, and bienzymatic system catalysts based on glucose oxidase and horseradish peroxidase were applied on an air-breathing cathode to address the overpotential loss in a body-friendly way. A single-layer Y-shaped channel configuration with a double-inlet was adopted. Microchannels of biofuel cells were patterned by silk screen printing with Ecoflex to maintain the flexibility of textile substrates without harm to the human body. The electrodes were fabricated with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and a mixture of multiwalled carbon nanotubes and single-walled carbon nanotubes by screen printing. The effects of electrode materials, catalyst type, catalyst concentration, and glucose concentration in the catholyte were investigated to optimize the fuel cell performance. The peak power density (44.9 µW cm-2) and maximum current density (388.9 µA cm-2) of the optimized hybrid biofuel cell were better than those of previously reported textile- or paper-substrate microscale single microbial fuel cells. The developed biofuel cell will be a useful platform as a microscale power source that is harmless to the environment and living organisms.

Reinforcing ß-tricalcium phosphate scaffolds for potential applications in bone tissue engineering: impact of functionalized multi-walled carbon nanotubes.

Beta-tricalcium phosphate (ß-TCP) scaffolds manufactured through the foam replication method are widely employed in bone tissue regeneration. The mechanical strength of these scaffolds is a significant challenge, partly due to the rheological properties of the original suspension. Various strategies have been explored to enhance the mechanical properties. In this research, ß-TCP scaffolds containing varying concentrations (0.25-1.00 wt%) of multi-walled carbon nanotubes (MWCNT) were developed. The findings indicate that the addition of MWCNTs led to a concentration-dependent improvement in the viscosity of ß-TCP suspensions. All the prepared slurries exhibited viscoelastic behavior, with the storage modulus surpassing the loss modulus. The three time interval tests revealed that MWCNT-incorporated ß-TCP suspensions exhibited faster structural recovery compared to pure ß-TCP slurries. Introducing MWCNT modified compressive strength, and the optimal improvement was obtained using 0.75 wt% MWCNT. The in vitro degradation of ß-TCP was also reduced by incorporating MWCNT. While the inclusion of carbon nanotubes had a marginal negative impact on the viability and attachment of MC3T3-E1 cells, the number of viable cells remained above 70% of the control group. Additionally, the results demonstrated that the scaffold increased the expression level of osteocalcin, osteoponthin, and alkaline phosphatase genes of adiposed-derived stem cells; however, higher levels of gene expersion were obtained by using MWCNT. The suitability of MWCNT-modified ß-TCP suspensions for the foam replication method can be assessed by evaluating their rheological behavior, aiding in determining the critical additive concentration necessary for a successful coating process.

Ultrasensitive carbon nanotube-bridged MXene conductive network arrays for one-step homogeneous electrochemical immunosensing of tumor markers.

Developing non-passivating and fully integrated electrode arrays for point-of-care testing of carcinoembryonic antigen (CEA) is crucial, as the serum level of CEA is closely associated with colorectal cancer. Herein, we propose a simple, low-cost, and eco-friendly template-assisted filtration method for the scalable preparation of carbon nanotube-bridged Ti3C2Tx MXene (MX@CNT) electrode arrays with a conductive network. Furthermore, we fabricate a homogeneous electrochemical (HEC) sensor for CEA detection by integrating a magnetic-bead-based alkaline phosphatase-linked immunoassay (MB-aElisa), which enables the in-situ generation of the electroactive substance 1-naphthol (1-NP). Benefiting from the unique electrochemical characteristics of a MX@CNT electrode array, such as ultra-low background signal and superior electrocatalytic activity towards the hydrolyzed 1-NP, the MB-aElisa-based HEC sensor specifically measures CEA within a detection range spanning from 0.005 to 1.0 ng mL-1, achieving a detection limit of 1.6 pg mL-1. Subsequently, this biosensing prototype is successfully utilized for the detection of CEA in serum specimens obtained from colorectal cancer patients. More importantly, the integration of MB-aElisa with a MX@CNT electrode array not only marks a significant advancement but also enables the creation of a one-step homogeneous electrochemical immunosensing platform, serving as a paradigm for the highly sensitive and selective measurement of trace tumor markers in complex biological samples.

Duffy Antigen Receptor for Chemokines (DARC) Nanodisc-Based Biosensor for Detection of Staphylococcal Bicomponent Pore-Forming Leukocidins.

Staphylococcus aureus (S. aureus) is an opportunistic infectious pathogen, which causes a high mortality rate during bloodstream infections. The early detection of virulent strains in patients' blood samples is of medical interest for rapid diagnosis. The main virulent factors identified in patient isolates include leukocidins that bind to specific membrane receptors and lyse immune cells and erythrocytes. Duffy antigen receptor for chemokines (DARC) on the surface of specific cells is a main target of leukocidins such as gamma-hemolysin AB (HlgAB) and leukocidin ED (LukED). Among them, HlgAB is a conserved and critical leukocidin that binds to DARC and forms pores on the cell membranes, leading to cell lysis. Current methods are based on ELISA or bacterial culture, which takes hours to days. For detecting HlgAB with faster response and higher sensitivity, we developed a biosensor that combines single-walled carbon nanotube field effect transistors (swCNT-FETs) with immobilized DARC receptors as biosensing elements. DARC was purified from a bacterial expression system and successfully reconstituted into nanodiscs that preserve binding capability for HlgAB. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) showed an increase of the DARC-containing nanodisc size in the presence of HlgAB, indicating the formation of HlgAB prepore or pore complexes. We demonstrate that this sensor can specifically detect the leukocidins HlgA and HlgAB in a quantitative manner within the dynamic range of 1 fM to 100 pM with an LOD of 0.122 fM and an LOQ of 0.441 fM. The sensor was challenged with human serum spiked with HlgAB as simulated clinical samples. After dilution for decreasing nonspecific binding, it selectively detected the toxin with a similar detection range and apparent dissociation constant as in the buffer. This biosensor was demonstrated with remarkable sensitivity to detect HlgAB rapidly and has the potential as a tool for fundamental research and clinical applications, although this sensor cannot differentiate between HlgAB and LukED as both have the same receptor.

Carbon Nanotubes as Controllable Electric-Field-Induced Bipolar Electrodes for Efficient Water Purification.

Advanced oxidation processes (AOPs) are the most efficient water cleaning technologies, but their applications face critical challenges in terms of mass/electron transfer limitations and catalyst loss/deactivation. Bipolar electrochemistry (BPE) is a wireless technique that is promising for energy and environmental applications. However, the synergy between AOPs and BPE has not been explored. In this study, by combining BPE with AOPs, we develop a general approach of using carbon nanotubes (CNTs) as electric-field-induced bipolar electrodes to control electron transfer for efficient water purification. This approach can be used for permanganate and peroxide activation, with superior performances in the degradation of refractory organic pollutants and excellent durability in recycling and scale-up experiments. Theoretical calculations, in situ measurements, and physical experiments showed that an electric field could substantially reduce the energy barrier of electron transfer over CNTs and induce them to produce bipolar electrodes via electrochemical polarization or to form monopolar electrodes through a single particle collision effect with feeding electrodes. This approach can continuously provide activated electrons from one pole of bipolar electrodes and simultaneously achieve "self-cleaning" of catalysts through CNT-mediated direct oxidation from another pole of bipolar electrodes. This study provides a fundamental scientific understanding of BPE, expands its scope in the environmental field, and offers a general methodology for water purification.

Catalytic methane decomposition on CNT-supported Fe-catalysts.

Methane, either as natural gas or as a resource obtained from various bioprocesses (e.g., digestion, landfill) can be converted to carbon and hydrogen according to. CH4(g)→C(s)+2H2(g)ΔH298K=74.8kJ/mol. Previous research has stressed the growing importance of substituting the high-temperature Steam Methane Reforming (SMR) by a moderate temperature Catalytic Methane Decomposition (CMD). The carbon formed is moreover of nanotube nature, in high industrial demand. To avoid the use of an inert support for the active catalyst species, e.g., Al2O3 for Fe, leading to a progressive contamination of the catalyst by support debris and coking of the catalyst, the present research investigates the use of carbon nanotubes (CNTs) as Fe-support. Average CH4 conversions of 75-85% are obtained at 700 °C for a continuous operation of 40 h. The produced CNT from the methane conversion can be continuously removed from the catalyst bed by carry-over due to its bulk density difference (∼120 kg/m3) with the catalyst itself (∼1500 kg/m3). CNT properties are fully specified. No thermal regeneration of the catalyst is required. A tentative process layout and economic analysis demonstrate the scalability of the process and the very competitive production costs of H2 and CNT.

Colorimetric and ECL dual-mode aptasensor for smartphone-based onsite sensitive detection of aflatoxin B1 in combination with ZnO@MWCNTs/g-C3N4 nanosheets and CuO@CuPt nanocomposites.

The development of dual-mode strategies with superior sensitivity and accuracy have garnered increasing attention for researchers in Aflatoxin B1 (AFB1) analysis. Herein, a colorimetric-electrochemiluminescence (ECL) dual-mode biosensor was constructed for onsite and ultrasensitive determination of AFB1. The multi-wall carbon nanotubes (MWCNTs) were integrated with the ZnO metal organic frameworks (MOFs) to accelerate the electron transfer and boost the ECL intensity of g-C3N4 nanoemitters. Through the aptamer-based DNA sandwich assay, the CuO@CuPt nanocomposites were introduced onto the electrode and acted as the dual functional signal nanoprobes. Due to the good spectrum overlap between the CuO@CuPt nanoprobes and g-C3N4 nanosheets, ECL signal could be efficiently quenched. Additionally, the CuO@CuPt nanoprobes show superior catalytic properties towards the TMB and H2O2 colorimetric reactions, and an obvious color alteration from colorless to blue can be observed using the smartphone. Under optimized conditions, a sensitive and accurate dual-mode analysis of the AFB1 was accomplished with the colorimetric detection limit of 3.26 fg/mL and ECL detection limit of 0.971 fg/mL (S/N = 3). This study combines innovative nanomaterial properties of ZnO@MWCNTs, g-C3N4 and CuO@CuPt for ultrasensitive dual-mode detection, which offers new opportunities for the innovative engineering of the dual-mode sensors and demonstrates significant potential in food safety analysis.

Fe3O4-Coated CNTs-Gum Arabic Nano-Hybrid Composites Exhibit Enhanced Anti-Leukemia Potency Against AML Cells via ROS-Mediated Signaling.

Background: Prior studies on magnetite (Fe3O4) NPs and carbon nanotubes (CNTs) cytotoxic effects against acute myeloid leukemia (AML) are inconclusive rather than definitive. Purpose: Investigation of the effects of Gum Arabic (GA)-stabilized/destabilized Fe3O4 NPs and CNTs, alone or in combination, on AML cell proliferation. Methods: Hybrid NPs were synthesized, characterized, and assessed for their cytotoxicity against Kasumi-1, HL-60, and THP-1 in comparison to normal primary bone marrow CD34+ cells. The molecular pathways of nanostructures' cytotoxicity were also investigated. Results: The Fe3O4 NPs were effectively synthesized and attached to the surface of the CNTs, resulting in the formation of a novel hybrid through their interaction with the GA colloidal solution in an aqueous media. Although the evaluated nanostructured nanoparticles had significant growth suppression ability against the leukemia cell lines, with IC50 values ranging from 42.437 to 189.842 µg/mL, they exhibited comparatively modest toxicity towards normal hematopoietic cells (IC50: 113.529‒162.656 µg/mL). The incorporation of Fe3O4 NPs with CNTs in a hybrid nanocomposite significantly improved their effectiveness against leukemia cells, with the extent of improvement varying depending on the specific cell type. The nanostructured particles were stabilized by GA, which enhances their ability to inhibit cell proliferation in a manner that depends on the specific cell type. Also, nanoparticles exhibit cytotoxicity due to their capacity to stimulate the production of intracellular ROS, halt the cell cycle at the G1 phase, and induce apoptosis. This is supported by the activation of p53, BAX, cytochrome C, and caspase-3, which are triggered by ROS. The nanostructures lead to an increase in the expression of genes encoding proteins related to oxidative stress (SIRT1, FOXO3, NFE2L2, and MAP3K5) and cyclin-dependent kinase inhibitors (CDKN1A and CDKN1B) in response to ROS. Conclusion: We provide an effective Fe3O4 NPs/CNTs nano-hybrid composite that induces apoptosis and has strong anti-leukemic capabilities. This hybrid nanocomposite is promising for in vivo testing and validation.

Sequence-Dependent Surface Coverage of ssDNA Coatings on Single-Wall Carbon Nanotubes.

A combination of experimental measurements and molecular dynamics (MD) simulations was used to investigate how the surfaces of single-wall carbon nanotubes (SWCNTs) are covered by adsorbed ssDNA oligos with different base compositions and lengths. By analyzing the UV absorption spectra of ssDNA-coated SWCNTs before and after coating displacement by a transparent surfactant, the mass ratios of adsorbed ssDNA to SWCNTs were determined for poly-T, poly-C, GT-containing, and AT-containing ssDNA oligos. Based on the measured mass ratios, it is estimated that an average of 20, 22, 26, or 32 carbon atoms are covered by one adsorbed thymine, cytosine, adenine, or guanine nucleotide, respectively. In addition, the UV spectra revealed electronic interactions of varying strengths between the nucleobase aromatic rings and the nanotube π-systems. Short poly-T DNA oligos show stronger π-π stacking interactions with SWCNT surfaces than do short poly-C DNA oligos, whereas both long poly-C and poly-T DNA oligos show strong interactions. These experiments were complemented by MD computations on simulated systems that were constrained to match the measured ssDNA/SWCNT mass ratios. The surface coverages computed from the MD results varied with oligo composition in a pattern that correlates higher measured yields of nanotube fluorescence with greater surface coverage.

Pt Loading of Phosphorus-Doped Carbon Nanotube Aerogels in Fuel Cell-Type Gas Sensors for Ultrasensitive H2 Detection.

A phosphorus-doped carbon nanotube (CNT) aerogel as the support material was loaded with Pt nanoparticles in fuel cell-type gas sensors for ultrasensitive H2 detection. The high surface area of the CNT scaffold is favorable to providing abundant active sites, and the high electrical conductivity facilitates the transport of carriers generated by electrochemical reactions. In addition, the CNT aerogel was doped with phosphorus (P) to further enhance the conductivity and electrochemical catalytic activity. As a result, the fuel cell-type gas sensor using the Pt/CNT aerogel doped with the optimal P content as the sensing material shows considerable performance for H2 detection at room temperature. The sensor exhibits an ultrahigh response of -921.9 µA to 15,000 ppm of H2. The sensitivity is -0.063 µA/ppm, which is 21 times higher than that of the conventional Pt/CF counterpart. The sensor also exhibits excellent repeatability and humidity resistance, as well as fast response/recovery; the response/recovery times are 31 and 4 s to 3000 ppm of H2, respectively. The modulation of the structure and catalytic properties of the support material is responsible for the improvement of the sensor performance, thus providing a feasible solution for optimizing the performance of fuel cell-type gas sensors.

Cytometry in the Short-Wave Infrared.

Cytometry plays a crucial role in characterizing cell properties, but its restricted optical window (400-850 nm) limits the number of stained fluorophores that can be detected simultaneously and hampers the study and utilization of short-wave infrared (SWIR; 900-1700 nm) fluorophores in cells. Here we introduce two SWIR-based methods to address these limitations: SWIR flow cytometry and SWIR image cytometry. We develop a quantification protocol for deducing cellular fluorophore mass. Both systems achieve a limit of detection of ∼0.1 fg cell-1 within a 30 min experimental time frame, using individualized, high-purity (6,5) single-wall carbon nanotubes as a model fluorophore and macrophage-like RAW264.7 as a model cell line. This high-sensitivity feature reveals that low-dose (6,5) serves as an antioxidant, and cell morphology and oxidative stress dose-dependently correlate with (6,5) uptake. Our SWIR cytometry holds immediate applicability for existing SWIR fluorophores and offers a solution to the issue of spectral overlapping in conventional cytometry.

Batch Fabrication of Flexible Strain Sensors with High Linearity and Low Hysteresis for Health Monitoring and Motion Detection.

In recent years, flexible strain sensors have gradually come into our lives due to their superiority in the field of biomonitoring. However, these sensors still suffer from poor durability, high hysteresis, and difficulty in calibration, resulting in great hindrance of practical application. Herein, starting with interfacial interaction regulation and structure-induced cracking, flexible strain sensors with high performance are successfully fabricated. In this strategy, dopamine treatment is used to enhance the bonding between flexible substrates and carbon nanotubes (CNT). The combination within the conductive networks is then controlled by substituting the CNT type. Braid-like fibers are employed to achieve controllable expansion of the conductive layer cracks. Finally, we obtain strain sensors that possess high linearity (R2 = 0.997) with low hysteresis (5%), high sensitivity (GF = 60) and wide sensing range (0-50%), short response time (62 ms), outstanding stability, and repeatability (>10,000 cycles). Flexible strain sensors with all performances good are rarely reported. Static and dynamic respiration and pulse signal monitoring by the fiber sensor are demonstrated. Moreover, a knee joint monitoring system is constructed for the monitoring of various walking stances, which is of great value to the diagnosis and rehabilitation of many diseases.

AuNPs-BP-MWCNTs-COOH-based electrochemical immunosensor for the determination of deoxynivalenol in wheat flour.

Deoxynivalenol (DON) has drawn considerable attention for its obvious pathogenicity and wide use in agro-products, which cause a potential threat to human health. In this work, an electrochemical immunosensor is developed for the highly sensitive and selective detection of DON in wheat flour using AuNPs-BP-MWCNTs-COOH and antibodies. The AuNPs-BP-MWCNTs-COOH nanocomposite was prepared via an in situ reduction reaction and ultrasonic-assisted liquid-phase exfoliation. The nanocomposite exhibits a larger surface area, decent stability, excellent electron transfer capability, good protein binding capability and prominent specificity. The plentiful carboxyl group on the nanocomposite can bind to the amino group of the antibody, and AuNPs have an affinity for the sulfhydryl group of the antibody, which makes it feasible for the nanocomposite to load the antibody. The peak currents are plotted against the logarithm of DON concentration from 0.002 to 80 ng mL-1 with a limit of detection (LOD) of 0.5 pg mL-1. This approach establishes an effective label-free immunosensor platform for the detection of DON with high sensitivity and selectivity in various food and agricultural products.