Single-walled Carbon Nanohorns Research Articles

Turn-off Fluorescent Determination of Adenosine Deaminase Using Oxidized Single-Walled Carbon Nanohorns

We present a simple and low-cost approach for adenosine deaminase (ADA) determination by assembling a purpose-designed carboxyfluorescein (FAM)-labeled aptamer with oxidized single-walled carbon nanohorns (oxSWCNHs). A carboxyfluorescein (FAM) labeled aptamer that had a strong affinity for adenosine was synthesized. The mixing of FAM-labeled aptamer with oxSWCNHs formed by a self-assembly of two components via their electrostatic interactions. As a result, the fluorescence of the FAM-labeled aptamer was quenched by the efficient electron transfer for the determination of adenosine deaminase. In the presence of adenosine, the FAM-labeled aptamer in the self-assembly was released from the oxSWCNHs surface, thereby inducing the fluorescence recovery. Upon reaction with ADA, the fluorescence of the complex was quenched as a consequence of the removal of adenosine converted into inosine which has no affinity for this aptamer. Thus, a simple and rapid strategy for assaying ADA is reported with a detection limit of 0.10 U/mL and linear range from 0.25 to 3.125 U/mL. The method was employed ADA in human and mouse serum.

Carbon nitride coupled with carbon nanohorns for improved photocatalytic hydrogen production and dyes degradation

In the present study we attempted to develop photoactive nanocomposites via the facile coupling of carbon nitride (CN) with single walled carbon nanohorns (CNHs). Photocatalytic activity was evaluated for the degradation of Rhodamine B (RhB) and the production of H2. The CNHs content noticeably affected the photoactivity of the nanocomposites and the best performing material exhibited a 3-fold increase in photocatalytic H2 production compared to pristine CN using 1 wt% Pt as co-catalyst. A systematic study was undertaken to explain the mechanistic aspects of the photo-reaction process. The active species responsible for the photodegradation of RhB were identified using reference reactions. Such species were further studied using in-situ spin-trap EPR experiments. Photoluminescence and time-resolved fluorescence decay kinetics suggested faster transfer of photogenerated electron/hole pairs resulting in reduced charge recombination phenomena in the nanocomposites. The combined photocatalytic application and characterization of the prepared materials revealed that the promotion of the redox reactions in based on improvements on the charge separation efficiency.

Novel Enzyme-Assisted Recycle Amplification Strategy for Tetracycline Detection Based on Oxidized Single-Walled Carbon Nanohorns.

In this study, oxidized single-walled carbon nanohorns (oxSWCNHs) were prepared using nitric acid oxidation and subsequently combined with 3'6-carboxyfluorescein through charge transfer to prepare fluorescent probes. These oxSWCNHs were used to quench fluorogen signals at short distances and dissociate ssDNA using cryonase enzymes. We established a method for rapidly detecting tetracycline (TC) in complex samples based on the amplification of cryonase enzyme signals. After optimizing the experimental conditions, our method showed a detection limit of 5.05 ng/mL, with good specificity. This method was used to determine the TC content in complex samples, yielding a recovery rate of 90.0-103.3%. This result validated the efficacy of our method in detecting TC content within complex samples.

A novel fluorescent aptasensor for the detection of theophylline based on cryonase-driven signal amplification strategy.

In the study, we have developed an expedient and efficient method for the detection of theophylline based on the amplification of the signal intensity of fluorescence based on oxidized single-walled carbon nanohorns (oxSWCNHs)/cryonase. When theophylline was not present in the system, oxSWCNHs can adequately adsorb nucleic acid probes labeled by carboxyfluorescein (FAM). In the presence of theophylline, the nucleic acid probe forms the tertiary probe-theophylline complex, which detaches from the surface of the oxSWCNHs. Then, upon reaction with cryonase, the complex can release the FAM and theophylline into the next cycle. The fluorescence signal of the system exhibits a 1:N magnification, enabling quantitative detection of theophylline. The linear range was 30-150 ng/mL, and the limit of detection (LOD) was 6.04 ng/mL. At the same time, it can also be used to detect theophylline in mouse serum.

Enhanced photocatalytic activity of amphiphilic single-walled carbon nanohorn–In0.2Cd0.8S composites for water splitting

Amphiphilic SWCNH–In0.2Cd0.8S photocatalysts with various contents of amphiphilic SWCNHs have been prepared and characterized. The photocurrent density and H2 production rate of the 0.38 wt% amphiphilic SWCNH–In0.2Cd0.8S photoelectrode (0.38 mA cm−2 and 3.73 μmol h−1 cm−2, respectively) were 1.6 and 2.88 times higher, respectively, than those of the bare In0.2Cd0.8S photoelectrode. The improved photocatalytic hydrogen evolution efficiency of the 0.38 wt% amphiphilic SWCNH–In0.2Cd0.8S photoelectrode is attributed to a synergetic effect of the intrinsic properties of its components, including excellent charge transfer and separation at the interface between the amphiphilic SWCNHs and the In0.2Cd0.8S photocatalyst.

Flame retardant effect of lignin/carbon nanohorns/potassium carbonate composite flame retardant on fir pretreated under different methods

Fir wood is widely used in construction, however its thermal degradability and flammability pose significant challenges to its safe use. In this work, we used a new carbonaceous nanomaterial called single-walled carbon nanohorns (SWCNHs), in combination with lignin and potassium carbonate to prepare a composite flame retardant and investigated the effect of different pretreatments on the flame retardant effect of fir wood. After delignification pretreatment and vacuum impregnation of fir wood with the flame retardant, the pk1-HRR and the pk2-HRR decreased by 37.59 % and 25.07 %, THP decreased by 55.71 %, TSP decreased by 59.81 %, COP significantly decreased by 74.02 %, char residual weight increased by 14.11 % compared with new wood (NW), and LOI reached 28.8 %. And the composite flame retardant forms a char layer during burning, which acts as a protective layer. This provides new insights into the application of SWCNHs in wood flame retardancy.

A Label-Free Aptasensor for Turn-On Fluorescent Detection of Aflatoxin B1 Based on an Aggregation-Induced-Emission-Active Probe and Single-Walled Carbon Nanohorns.

The determination of the aflatoxin B1 (AFB1) content has received widespread attention in the context of food safety, which is a global public health issue. Accordingly, a label-free and turn-on fluorescent AFB1 determination method is developed herein with an ss-DNA aptamer as the recognition element, 4, 4-(1E,1E)-2, 2-(anthracene-9, 10-diyl) bis(ethene-2, 1-diyl) bis(N, N, N-trimethylbenzenaminium iodide) (DSAI) as the aggregation-induced emission (AIE) fluorescent probe, and single-walled carbon nanohorns (SWCNHs) as the selective part with a fluorescence quenching effect. In the presence of AFB1, the AFB1-specific aptamer undergoes a structural transformation and switches from being a random helix to a folded structure. DSAI's fluorescence is protected as a result of the resistance of the transformed aptamer adsorbed on the SWCNHs' surface. Because DSAI's fluorescence is not quenchable, the fluorescence intensity is calculated as a function of the AFB1 concentration. By simply mixing DSAI, aptamer, AFB1 samples, and SWCNHs, the method can be carried out in 2 h, with a limit of detection (LOD) of 1.83 ng/mL. It has a high selectivity in the presence of other mycotoxins, and its performance is confirmed in soybean sauce with a known concentration of AFB1. The LOD was 1.92 ng/mL in the soy sauce samples and the recovery ranged from 95 to 106%, implying that the presented aptasensor has great potential for food analysis.

Colossal C130 Fullertubes: Soluble [5,5] C130-D5h(1) Pristine Molecules with 70 Nanotube Carbons and Two 30-Atom Hemifullerene End-caps.

We report the seminal experimental isolation and DFT characterization of pristine [5,5] C130-D5h(1) fullertubes. This achievement represents the largest soluble carbon molecule obtained in its pristine form. The [5,5] C130 species is the highest aspect ratio fullertube purified to date and now surpasses the recent gigantic [5,5] C120-D5d(1). In contrast to C90, C100, and C120 fullertubes, the longer C130-D5h has more nanotubular carbons (70) than end-cap fullerenyl atoms (60). Starting from 39,393 possible C130 isolated pentagon rule (IPR) structures and after analyzing polarizability, retention time, and UV-vis spectra, these three layers of data remarkably predict a single candidate isomer and fullertube, [5,5] C130-D5h(1). This structural assignment is augmented by atomic resolution STEM data showing distinctive and tubular "pill-like" structures with diameters and aspect ratios consistent with [5,5] C130-D5h(1) fullertubes. The high selectivity of the aminopropanol reaction with spheroidal fullerenes permits facile separation and removal of fullertubes from soot extracts. Experimental analyses (HPLC retention time, UV-vis, and STEM) were synergistically used (with polarizability and DFT property calculations) to down select and confirm the C130 fullertube structure. Achieving the isolation of a new [5,5] C130-D5h fullertube opens the door to application development and fundamental studies of electron confinement, fluorescence, and metallic character for a fullertube series of molecules with systematic tubular elongation. This [5,5] fullertube family also invites comparative studies with single-walled carbon nanotubes (SWCNTs), nanohorns (SWCNHs), and fullerenes.

Retraction Note: Single-wall carbon nanohorns inhibited activation of microglia induced by lipopolysaccharide through blocking of Sirt3

Retraction Note: Single-wall carbon nanohorns inhibited activation of microglia induced by lipopolysaccharide through blocking of Sirt3

Fluorescence Sensor for Zearalenone Detection Based on Oxidized Single-walled Carbon Nanohorns/N-doped Carbon Quantum Dots-aptamer.

Zearalenone (ZEN), a resorcinolactone toxin, which has been a potential threat to agricultural production and human health. In this study, a sample and rapid fluorescence sensor was established for the detection of ZEN, which is based on the fluorescence properties of N-doped carbon dots-aptamer (NCDs-apt) and the quenching ability of oxidized single-walled carbon nanohorns (oxSWCNHs). NCDs synthesized by one-step hydrothermal method were connected with ZEN-aptamer (ZEN-apt), and oxSWCNHs were added to quench the fluorescence of NCDs-apt. Therefore, an oxSWCNHs/NCDs-apt aptasensor based on fluorescence "on-off" for the determination of ZEN in food was formed. Under optimum conditions, the limit of detection (LOD) of this method was 18 ng/mL and the linear range was 20 ~ 100 ng/mL. The possible interfering substances were investigated, and the results showed excellent selectivity. The recoveries were in the range of 99.5%~114.3%, and the relative standard deviations (RSDs) were not more than 6.5%, which demonstrated that this aptasensor was successfully applied for the detection of ZEN in food samples with satisfactory result.

Nanohybrid Composites Based on TiO2 and Single-Walled Carbon Nanohorns as Promising Catalysts for Photodegradation of Amoxicillin.

In this work, applications of nanohybrid composites based on titanium dioxide (TiO2) with anatase crystallin phase and single-walled carbon nanohorns (SWCNHs) as promising catalysts for the photodegradation of amoxicillin (AMOX) are reported. In this order, TiO2/SWCNH composites were prepared by the solid-state interaction of the two chemical compounds. The increase in the SWCNH concentration in the TiO2/SWCNH composite mass, from 1 wt.% to 5 wt.% and 10 wt.% induces (i) a change in the relative intensity ratio of the Raman lines located at 145 and 1595 cm-1, which are attributed to the Eg(1) vibrational mode of TiO2 and the graphitic structure of SWCNHs; and (ii) a gradual increase in the IR band absorbance at 1735 cm-1 because of the formation of new carboxylic groups on the SWCNHs' surface. The best photocatalytic properties were obtained for the TiO2/SWCNH composite with a SWCNH concentration of 5 wt.%, when approx. 92.4% of AMOX removal was achieved after 90 min of UV irradiation. The TiO2/SWCNH composite is a more efficient catalyst in AMOX photodegradation than TiO2 as a consequence of the SWCNHs' presence, which acts as a capture agent for the photogenerated electrons of TiO2 hindering the electron-hole recombination. The high stability of the TiO2/SWCNH composite with a SWCNH concentration of 5 wt.% is proved by the reusing of the catalyst in six photodegradation cycles of the 98.5 μM AMOX solution, when the efficiency decreases from 92.4% up to 78%.

Ni(II)-Complex Anchored onto Magnetically Separable Oxidized Single-Walled Carbon Nanohorn: A DFT-Supported Mechanistic Approach for Hydrogen-Borrowing Quinoxaline Synthesis

Ni(II)-Complex Anchored onto Magnetically Separable Oxidized Single-Walled Carbon Nanohorn: A DFT-Supported Mechanistic Approach for Hydrogen-Borrowing Quinoxaline Synthesis

Electrical bridging effects of dual-carbon microsphere frameworks in Si-based composite anodes for high-performance Li-ion batteries

Herein, the successful fabrication of a high-performance Si-based composite Li-ion battery (LIB) anode, comprising a dual-carbon framework of reduced graphene oxide (r-GO) and oxidized single-walled carbon nanohorns (o-NHs), was demonstrated using a simple and scalable spray-drying process followed by heat treatment (h-s-GO/Si/NH). The r-GO nanosheets in the h-s-GO/Si/NH anode acted as a robust spherical framework that facilitated the mechanical and electrical connection between the carbon-coated Si (c-Si) nanoparticles, homogeneous dispersion of c-Si and o-NH nanoparticles, and suppression of the volume expansion and pulverization that occur during lithiation/delithiation. Additionally, the o-NH nanoparticles incorporated in the h-s-GO/Si/NH composite served as electrical bridges between the r-GO nanosheets, resulting in enhanced electrical conductivity and effortless Li-ion shuttling. The h-s-GO/Si/NH composite anode exhibited high electrochemical performance with a very high initial gravimetric charge capacity (2961 mAh g−1 at 0.1 A g−1), stable initial Coulombic efficiency (80.6% at 0.2 A g−1), and high cycling stability (983 mAh g−1 at 0.2 A g−1 after 50 cycles). This study highlights the importance of the effective design of electrically conductive three-dimensional frameworks in Si-based composite anodes, which may contribute to the development of high-performance LIB anode materials.

Electrochemical Determination of Acetaminophen Using a Hydrophilic Single-Walled Carbon Nanohorn Modified Glassy Carbon Electrode

A simple and novel electrochemical sensor based on a hydrophilic single-walled carbon nanohorn (SWCNH) modified glassy carbon electrode (GCE) was designed for the determination of acetaminophen (APAP). The hydrophilic SWCNH/GCE was characterized using Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS). This proposed sensor exhibits remarkable performance for the electrocatalytic detection of APAP. The hydrophilic SWCNH/GCE shows a good differential pulse voltammetry (DPV) response at APAP concentration from 100 to 1000 μM with sensitivity and a detection limit of 2.63 μAμM−1cm−2 and 1 μM. Regarding the reaction mechanism, the hydrophilic SWCNH/GCE could easily electro-catalyze APAP oxidation to form N-acetyl-p-benzoquinone-imine (NAPQI). Then NAPQI is rapidly degraded to p-benzoquinone in solutions of 0.1 M Na2SO4 and 0.05 M H2SO4 at pH 1.

(Invited) Precise Evaluation of Functional Group Distribution and Reaction Yield for Chemically Treated Carbon Nanohorns by Highly Sensitive SEM-EDS

Single-walled carbon nanohorns (CNHs) have great potential in diverse applications such as catalyst support, energy conversion, and drug carriers. Although chemical functionalization of CNHs is critical for these applications, they inherently form robust spherical “dahlia-like” aggregates, which may inhibit chemical reactivity. Herein, highly sensitive energy-dispersive X-ray spectrometry (EDS) analysis in scanning electron microscopy (SEM) is employed to elucidate the functional group distribution and the reaction yield of CNH dahlia aggregates. First, the technique clearly visualizes the elemental distribution associated with the functional groups on dahlia structures with a sufficient spatial resolution of <10 nm.1 The result exposes that the outer surface of an individual aggregate is functionalized while the inner core remains almost unreacted. Second, the SEM-EDS precisely assesses the reaction yield for functionalized CNHs.2 The sensitive elemental analysis enables the evaluation of functionalization efficiency for sequentially grown polyamidoamine dendrimers on CNH surface, which consistently explains the change of chemical structure according to the reaction process. The details about the functionalization mechanism on CNH surface will be discussed in the conference.[1] H. Nakajima, T. Morimoto, K. Kobashi, M. Zhang, I. K. Sideri, N. Tagmatarchis, and T. Okazaki, Outer-Surface Covalent Functionalization of Carbon Nanohorn Spherical Aggregates Assessed by Highly Spatial-Resolved Energy-Dispersive X-ray Spectrometry in Scanning Electron Microscopy, J. Phys. Chem. C 2020, 124, 25142-25147.[2] H. Nakajima, K. Kobashi, C. Stangel, T. Morimoto, M. Zhang, N. Tagmatarchis, and T. Okazaki, Step-by-step Characterization of a Series of Polyamidoamine Dendrimers on Carbon Nanohorn Surface, submitted.

Single-Wall Carbon Nanohorn Langmuir-Schaefer Films.

A suspension of single-walled carbon nanohorn (SWCNH) aggregates with a size of approx. 50 nm was used to create a floating film at the water-air interface. The film was then transferred onto large-area quartz substrates using the Langmuir-Schaefer technique at varied surface pressures. The packaging and arrangement of SWCNHs in the film can be controlled during the process. The resulting films' optical and electrical properties were investigated, and the highest electrical conductivity and figure of merit parameter values were observed for the film transferred at surface pressure near the collapse point. These films had a surface density of less than 5 μg cm-2, making them ideal for use in ultra-light sensors, supercapacitors, and photovoltaic cell electrodes. The preparation and properties of the Langmuir-Schaefer films of carbon nanohorns are reported for the first time.

Single-Walled Carbon Nanohorn-Based Fluorescence Energy Resonance Transfer Aptasensor Platform for the Detection of Aflatoxin B1.

Aflatoxin B1 (AFB1) is one of the most contaminated fungal toxins worldwide and is prone to cause serious economic losses, food insecurity, and health hazards to humans. The rapid, on-site, and economical method for AFB1 detection is need of the day. In this study, an AFB1 aptamer (AFB1-Apt) sensing platform was established for the detection of AFB1. Fluorescent moiety (FAM)-modified aptamers were used for fluorescence response and quenching, based on the adsorption quenching function of single-walled carbon nanohorns (SWCNHs). Basically, in our constructed sensing platform, the AFB1 specifically binds to AFB1-Apt, making a stable complex. This complex with fluorophore resists to be adsorbed by SWCNHs, thus prevent SWCNHs from quenching of fluorscence, resulting in a fluorescence response. This designed sensing strategy was highly selective with a good linear response in the range of 10-100 ng/mL and a low detection limit of 4.1 ng/mL. The practicality of this sensing strategy was verified by using successful spiking experiments on real samples of soybean oil and comparison with the enzyme-linked immunosorbent assay (ELISA) method.

In Situ Surface Decoration of Single-Wall Carbon Nanohorn with Pt/MnO2 and its application for Supercapacitors

In Situ Surface Decoration of Single-Wall Carbon Nanohorn with Pt/MnO2 and its application for Supercapacitors

Single-walled carbon nanohorns promote apple growth by regulating carbohydrate allocation and metabolism

Single-walled carbon nanohorns (SWCNHs) regulate plant growth and stress response. However, interaction mechanism between SWCNHs and plants remains largely unknown. This study aimed to evaluate if SWCNHs-mediated plant growth can be correlated with carbohydrate allocation and metabolism. Our results showed that foliar spraying of 100 mg/L SWCNHs significantly promoted the growth of apple seedlings, as indicated by increased dry weight, fresh weight, total root length, root surface area, root volume, leaf photosynthesis rate and chlorophyll contents. The TEM results revealed that SWCNHs particles were absorbed by apple leaf cells. SWCNHs application enhanced A6PR activity and MdA6PR expression, accompanied by increased amount of photosynthetic assimilate‒sorbitol in apple leaves. Activities of SDH, SUSY, FRK and HK, all of which are key enzymes related to carbohydrate catabolism, were higher in roots of SWCNHs-treated apple seedlings than that in control apple roots. Transcript levels of MdA6PR, MdSPS1, MdSDH2, MdSUSY3, MdFRK2, MdHK1, MdSOT1/2 and MdTMT1/3 were upregulated, whereas transcript levels of MdSPS6, MdUGP1/3 and MdPGM1/2 were downregualted in SWCNHs-treated plants. These findings indicate that foliar spraying SWCNHs increases the synthesis of photosynthate in apple leaves, and improves unloading and utilization capacity of carbohydrate in apple roots. These results establish the theoretical foundation for the application of SWCNHs in horticultural production and plant biotechnology.

High-Performance Aqueous Zinc-Ion Batteries Based on Multidimensional V2 O3 Nanosheets@Single-Walled Carbon Nanohorns@Reduced Graphene Oxide Composite and Optimized Electrolyte.

The drawbacks of poor electronic conductivity and structural instability during the cycling process limit the electrochemical property of vanadium-based cathode materials for aqueous zinc-ion batteries. In addition, continuous growth and accumulation of zinc dendrites can puncture the separator and cause an internal short circuit in the battery. In this work, a unique multidimensional nanocomposite is designed by a facile freeze-drying method with subsequent calcination, consisting of V2 O3 nanosheets and single-walled carbon nanohorns (SWCNHs) crosslinked together and wrapped by reduced graphene oxide (rGO). The multidimensional structure can largely enhance the structural stability and electronic conductivity of the electrode material. Besides, additive Na2 SO4 in the ZnSO4 aqueous electrolyte not only prevents the dissolution of cathode materials but also suppresses the Zn dendrite growth. After considering the influence of additive concentration on ionic conductivity and electrostatic force for electrolyte, V2 O3 @SWCNHs@rGO electrode delivers a high initial discharge capacity of 422 mAh g-1 at 0.2 A g-1 and a high discharge capacity of 283 mAh g-1 after 1000 cycles at 5 A g-1 in 2m ZnSO4 + 2m Na2 SO4 electrolyte. Experimental techniques reveal that the electrochemical reaction mechanism can be expressed as the reversible phase transformation between V2 O5 and V2 O3 with Zn3 (VO4 )2 .