Building synergistic multiple active sites in branch-leaf nanostructured carbon nanofiber derived from MOF/COF hybrid for flexible wearable Zn-air battery

Covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) have attracted growing attention in electrochemical energy storage and conversion systems (e.g., Zn-air batteries, ZABs) owing to their structural tunability, ordered porosity and high specific surface area. In this work, for the first time, the three-dimensional (3D) highly open catalyst (CNFs/CoZn-MOF@COF) possessing hierarchical porous structure and high-density active sites of uniform cobalt (Co) nanoparticles and metal-Nx (M-Nx, M = Co and Zn) is demonstrated, which is fabricated using electrospinning technique in combination with MOF/COF hybridization strategy and direct pyrolysis. Benefiting from the well-designed branch-leaf nanostructures, plentiful and uniform active sites on the MOF/COF-derived carbon frameworks, as well as the synergistic effect of multiple active sites, CNFs/CoZn-MOF@COF catalyst achieves superior electrocatalytic activity and stability towards both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with a small potential gap (ΔE = 0.75 V). In situ Raman spectroscopy and X-ray photoelectron spectroscopy results indicate that the CoOOH intermediates are the main active species during OER/ORR. Significantly, both aqueous and all-solid-state rechargeable ZABs assembled with CNFs/CoZn-MOF@COF as the air cathode show high open-circuit potential, outstanding peak power density, large capacity and long cycle life. More impressively, the obtained all-solid-state ZAB also displays superb mechanical flexibility and device stability under different, showcasing great application deformations potential in portable and wearable electronics. This work provides a new insight into the design and exploitation of bifunctional catalysts from MOF/COF hybrid materials for energy storage and conversion devices.

An aptamerelectrochemical sensor based on functional carbon nanofibers for tetracycline determination

Fe-Co@CNF was synthesized by electrospinning technology, and AuNPs was loaded onto Fe-Co@CNF by in-situ reduction to obtain Fe-Co@CNF@AuNPs composite material, which was used as the working electrode based on Au-S bond cooperation. The tetracycline electrochemical sensing interface Fe-Co@CNF@AuNPs@Apt was constructed by connecting mercaptoylated tetracycline (TC) aptamers on Fe-Co@CNF@AuNPs surface. The morphology and composition of Fe-Co@CNF@AuNPs composites were characterized by SEM, TEM, EDS, XRD and XPS, and the electrochemical properties of tetracycline were evaluated by CV and DPV. The results showed that the addition of Fe and Co did not destroy the structure of the original carbon nanofibers, and their synergistic effect enhanced the electrocatalytic performance, effective electrode area and electron transfer ability of carbon nanofibers. AuNPs are evenly distributed over the fibers, which effectively improves the electrical conductivity of the material. Under the optimal conditions, the theoretical detection limit of tetracycline was 0.213 nM, and the linear detection range was 5.12-10 mM, which could successfully detect tetracycline in milk.

Electrocatalytic reduction of furfural to furfuryl alcohol using carbon nanofibers supported zinc cobalt bimetallic oxide with surface-derived zinc vacancies in alkaline medium

Electrocatalytic hydrogenation (ECH) reduction provides an environment-friendly alternative to conventional method for the upgrade of furfural to furfuryl alcohol. At present, exploring superior catalysts with high activity and selectivity, figuring out the reduction mechanism in aqueous alkaline environment are urgent. In this work, zinc cobalt bimetallic oxide (ZnMn2O4) with surface-derived Zn2+ vacancies supported by carbon nanofibers (d-ZnMn2O4-C) was fabricated. The d-ZnMn2O4-C exhibited excellent performance in electrocatalytic reduction of furfural, high furfuryl alcohol yield (49461.1 ± 228 µmol g-1) and Faradaic efficiency (95.5 ± 0.5 %) was obtained. In-depth research suggested that carbon nanofiber may strongly promoted the production of adsorbed hydrogen (Hads), and Zn2+ vacancies may significantly lowered the energy barrier of furfural reduction to furfuryl alcohol, the synergistic effect between carbon nanofiber and d-ZnMn2O4 probably facilitated the reaction between Hads and furfuryl alcohol radical, thereby promoting the formation of furfuryl alcohol. Furthermore, the reaction mechanism was clarified by inhibitor coating and isotope experiments, the results of which revealed that the conversion of furfural to furfuryl alcohol on d-ZnMn2O4-C followed both ECH and direct electroreduction mechanism.

Nano-scaled polyacrylonitrile for industrialization of nanofibers with photoluminescence and microbicide performance

Nanofibers are investigated to be superiorly applicable in different purposes such as drug delivery systems, air filters, wound dressing, water filters, and tissue engineering. Herein, polyacrylonitrile (PAN) is thermally treated for autocatalytic cyclization, to give optically active PAN-nanopolymer, which is subsequently applicable for preparation of nanofibers through solution blow spinning. Whereas, solution blow spinning is identified as a process for production of nanofibers characterized with high porosity and large surface area from a minimum amounts of polymer solution. The as-prepared nanofibers were shown with excellent photoluminescence and microbicide performance. According to rheological properties, to obtain spinnable PAN-nanopolymer, PAN (12.5-15% wt/vol, honey like solution, 678-834 mPa s), thermal treatment for 2-4 h must be performed, whereas, time prolongation resulted in PAN-nanopolymer gelling or rubbering. Size distribution of PAN-nanopolymer (12.5% wt/vol) is estimated (68.8 ± 22.2 nm), to reflect its compatibility for the production of carbon nanofibers with size distribution of 300-400 nm. Spectral mapping data for the photoluminescent emission showed that, PAN-nanopolymer were exhibited with two intense peaks at 498 nm and 545 nm, to affirm their superiority for production of fluorescent nanofibers. The microbial reduction % was estimated for carbon nanofibers prepared from PAN-nanopolymer (12.5% wt/vol) to be 61.5%, 71.4% and 81.9%, against S. aureus, E. coli and C. albicans, respectively. So, the prepared florescent carbon nanofibers can be potentially applicable in anti-infective therapy.

An electrochemical sensor based on carbon nanofiber and molecular imprinting strategy for dasatinib recognition

Herein, we proposed a new approach to design a MIP-based electrochemical sensor with carbon nanofiber (CNF), which could improve its conductivities as well as electrode sensitivity and successful detection of dasatinib (DAS). CNFs are capable of forming high porosity with significant interconnected porous networks. The poly(2-hydroxyethyl-methacrylate-N-methacryloyl-L-tyrosine) (PHEMA-MATyr) copolymer was synthesized in the presence of both CNF and DAS by photopolymerization. After optimization of the parameters, the modified MIP-based electrochemical sensor demonstrated the ability to determine the DAS in the linear working range of 1.0 × 10-14-1.0 × 10-13 M for the standard solution and commercial serum samples with a LOD of 1.76 × 10-15 and 2.46 × 10-15, respectively. Good linearity for DAS was observed with correlation coefficients (r) of 0.996 and 0.997 for the standard solution and commercial serum samples, respectively. The recoveries of the DAS ranged from 99.45 % to 99.53 % for the tablet dosage form and commercial serum samples, with average relative standard deviations below 1.96 % in both cases. The proposed modified sensor demonstrated significant sensitivity and selectivity for the rapid determination of DAS in commercial serum samples and tablet form.

Preparation, characterization, electrical conductivity, and life cycle assessment of carbon nanofibers-reinforced Ecuadorian natural zeolite-based geopolymer composites

Geopolymers are inorganic crosslinked polymers with much less carbon footprint than ordinary Portland cement. Geopolymers and geopolymer-based materials have superior mechanical and durability properties with extreme thermal and chemical resistance. Carbon nano- or microfibers-reinforced geopolymers show potential properties such as electric conductivity, enhanced mechanical and thermal stability, and multi-functionality. This study evaluated the effect of incorporating carbon nanofibers in natural zeolite-based geopolymers and their impact on the mechanical, thermal, and electric conductivity of yielded geopolymer composites. Additionally, a life cycle assessment for 1 m3 geopolymer and its carbon fiber reinforced geopolymers' production has been conducted to evaluate the environmental impact of the processes.

Carbon nanofibers/liquid metal composites for high temperature laser ultrasound

As the demand for clean energy becomes greater worldwide, there will also be an increasing demand for next generation nuclear power plants that incorporate advanced sensors and monitoring equipment. A major challenge posed by nuclear power plants is that, during normal operation, the reactor compartment is subjected to high operating temperatures and radiation flux. Diagnostic sensors monitoring such structures are also subject to temperatures reaching hundreds of degrees Celsius, which puts them at risk for heat degradation. In this work, the ability of carbon nanofibers to work in conjunction with a liquid metal as a photoacoustic transmitter was demonstrated at high temperatures. Fields metal, a Bi-In-Sn eutectic, and gallium are compared as acoustic mediums. Fields metal was shown experimentally to have superior performance over gallium and other reference cases. Under stimulation from a low fluence 6 ns pulse laser at 6 mJ/cm2 with 532 nm green light, the Fields metal transducer transmitted a 200 kHz longitudinal wave with amplitude >5.5 times that generated by a gallium transducer at 300 °C. Each high temperature test was conducted from a hot to cold progression, beginning as high as 300 °C, and then cooling down to 100 °C. Each test shows increasing signal amplitude of the liquid metal transducers as temperature decreases. Carbon nanofibers show a strong improvement over previously used candle-soot nanoparticles in both their ability to produce strong acoustic signals and absorb higher laser fluences up to 12 mJ/cm2.

Disposable biosensor based on ionic liquid, carbon nanofiber and poly(glutamic acid) for tyramine determination

In this study, an electrochemical biosensor based on carbon nanofibers (CNF), ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (IL), poly(glutamic acid) (PGA) and tyrosinase (Tyr) modified screen printed carbon electrode (SPE) was constructed for tyramine determination. Optimum experimental parameters such as CNF and IL amount, polymerization conditions of glutamic acid, enzyme loading, pH of test solution and operating potential were explored. The construction steps of the Tyr/PGA/CNF-IL/SPE were pursued by scanning electron microscopy and cyclic voltammetry. The Tyr/PGA/CNF-IL/SPE biosensor exhibited linear response to tyramine in the range of 2.0 × 10-7 - 4.8 × 10-5 M with a low detection limit of 9.1 × 10-8 M and sensitivity of 302.6 μA mM-1. The other advantages of Tyr/PGA/CNF-IL/SPE include its high reproducibility, good stability and anti-interference ability. The presented biosensor was also applied for tyramine determination in malt drink and pickle juice samples and mean analytical recoveries of spiked tyramine were calculated as 100.6% and 100.4% respectively.

Oxygen vacancy modulation in interfacial engineering Fe3O4 over carbon nanofiber boosting ambient electrocatalytic N2 reduction

The oxygen vacancy modulation of interface-engineered Fe3O4 nanograins over carbon nanofiber (Fe@CNF) was achieved to improve electrocatalytic nitrogen reduction reaction (NRR) activity and stability via facile electrospinning and tuning thermal procedure. The optimal catalyst calcined at 800 ℃ (Fe@CNF-800) was endowed with abundant nanograin boundaries and optimized oxygen vacancy (Vo) concentration of iron oxides, thereby affording 37.1 μg h-1 mgcat.-1 (-0.2 V vs. reversible hydrogen electrode (RHE)) NH3 yield and rational Faraday efficiency (10.2%), with 13.6 times atomic activity enhancement compared to of that commercial Fe3O4. The interfacial effect of assembled nanograins in particles correlated with the formation of Vo and more intrinsic active sites, which is conducive to the trapping and activation of nitrogen (N2). The in-situ X-ray photoelectron spectroscopy (XPS) measurement revealed the real consumption of adsorbed oxygen when introducing N2 by the trapping effect of Vo. Density-Functional-Theory (DFT) calculation validates the promotive hydrogenation effect and elimination of hydrogen intermediate (H*) interacted with N2 transferring toward oxygen of the support. The optimal catalyst shows a lasting NRR activity at least 90 h, outperforming most reported Fe-based NRR catalysts.

Lanthanum vanadate-based carbon nanocomposite as an electrochemical probe for amperometric detection of theophylline in real food samples

Theophylline (THP) is an emerging drug for chronic obstructive pulmonary disease whose side effects can be greatly affected by caffeine-containing real foods. Because an overdose of this substance can cause respiratory and neurological damage, producing a fast and accurate analytical procedure is critical. Based on a cutting-edge hybrid nanocomposite, this study was used to construct an electrochemical sensor for the accurate detection of THP. Spectroscopy and morphological investigation supported the easy synthesis of tetragonal-LaVO₄ (t-LV) nanopellets and LV@CNF hybrid nanocomposite. To detect THP, a highly dispersed LV@CNF nanocomposite was modified on a glassy carbon electrode as a sensing substrate. By amperometric technique, the sensor shows a wide linear range of 0.01-1070 μM, low limit of detection (2.63 nM), and sensitivity (0.228 μA μM^-1 cm^-2). Finally, the current technique was successfully used to identify THP in real food samples (chocolate, coffee and black tea).

Lanthanum nickelate spheres embedded acid functionalized carbon nanofiber composite: An efficient electrocatalyst for electrochemical detection of food additive vanillin

Contemporary food marketing is ruined by flavor enhancers rather than emphasizing the nutritional value of food. Vanillin is an overexploited flavor enhancer added to food items, thereby necessitating its detection. In this study, an electrochemical sensor was designed using a modified electrode made up of La₂NiO₄ functionalized carbon nanofiber (f-CNF) to effectively detect vanillin in food samples. To confirm the successful formation of La₂NiO₄/f-CNF, structural and morphological studies were performed using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Further electrochemical analysis was performed using cyclic voltammetry and differential pulse voltammetry techniques, which resulted in high sensitivity (0.2899 µA·μM^-1·cm^-2) and low limit of detection (LOD) (6 nM). This modified electrode material was tested in food samples, which showed an excellent response with recovery percentage and is a promising electrocatalyst for vanillin detection.

The orientation and inhomogeneous distribution of carbon nanofibers and distinctive internal structure in polymer composites induced by 3D-printing enabling electromagnetic shielding regulation

Carbon nanofiber (CNF)/polycaprolactone (PCL) composites were three-dimention (3D) printed into electromagnetic interference (EMI) shielding parts. 3D-printing process led to an inhomogeneous CNFs distribution in printed composites. The special high-resistance "internal surfaces" introduced between printed threads reduced the conductivity of printed parts and resulted in characteristic secondary percolation phenomena. Meanwhile, the accelerated melt flow in nozzle oriented CNFs in composites along the printing direction, increasing the percolation threshold compared to the random arrangement. As two stage of percolation networks formed, the 3D-printed CNF/PCL parts exhibited excellent EMI shielding performance, with EMI shielding effectiveness value up to 58.7 dB. By controlling the packing density of the printed part, a large number of apertures and heterogeneous interfaces were easily introduced into the interior of parts. It promoted multiple reflection and absorption of electromagnetic waves inside the parts, and enabled adjustment of weight and shielding effectiveness. Therefore, the 3D printing enabled the flexible formation of complex porous structures. From basic materials to designed components, the 3D printing technology can facilitate the transformation of shielding materials into high performance components that are finely designed both internally and externally, making it a promising technology in the field of manufacturing lightweight, high performance EMI shielding materials.

Heterostructure-induced enhanced oxygen catalysis behavior based on metal cobalt coupled with compound anchored on N-doped carbon nanofiber for microbial fuel cell

High-efficiency oxygen reduction reaction (ORR) electrocatalyst in microbial fuel cells (MFCs) is important to boost the power production efficiency and reduce overall cost. Herein, we demonstrate a novel nitrogen (N)-doped carbon nanofiber (N-CNF) supported metal and metal compound heterostructure derived from metal-organic frameworks (MOFs), which endows superior electrocatalytic activity by optimizing the coupling modulation effect. The resulting cobalt/cobalt phosphide and cobalt/cobalt sulfide nanoparticles embedded in N-doped carbon nanofiber (Co/CoP/Co₂P@N-CNF, Co/CoS₂@N-CNF) present superior ORR activity and methanol tolerance. Moreover, the assembled MFCs modified with Co/CoP/Co₂P@N-CNF and Co/CoS₂@N-CNF composite also achieve higher power density (375.16 and 400.06 mW m^-2) as well as coulombic efficiency (11.2 %, 12.4 %), superior than that of Pt/C electrode (333.70 mW m^-2, 10.4 %). Impressively, the Co/CoS₂@N-CNF electrode exhibits long-term stability and durability in dual-chamber MFCs. A high-performance heterostructure cathode with an effective strategy for bridging nanocatalysis and practical MFCs is reported and presented.

Screen printed electrodes on interfacial Pt-CuO/carbon nanofiber functional ink for real-time qualification of cell released hydrogen peroxide

Screen printed electrode (SPE) on carbon-based inks exhibits promising applications in biosensing, environment protection and food safety. We report here a unique carbon-based material comprising Pt-CuO nanocrystal interfacially anchored on functionalized carbon nanofiber (Pt-CuO@FCNF) and its functional ink to build SPE for ultrasensitive detection of cell released H₂O₂. Pt-CuO@FCNF is fabricated using a one-pot and mass production method through direct pyrolysis of Pt and CuO precursors together with FCNF. FCNF with 1-D structure and high electrical conductivity can interfically anchor Pt-CuO nanocrystal, which synergically promotes rich active site and catalytic activity towards H₂O₂. Pt-CuO@FCNF exhibits a wide linear response of 0.4 μM-11 mM, a low detection limit of 17 nM, a fast response time of 1.0 s, and good selectivity. Eventually, Pt-CuO@FCNF SPE realizes real-time and ultrasensitive qualification of H₂O₂ released from both normal and cancer cells.

Efficient removal of Cs ion by electrochemical adsorption and desorption reaction using NiFe Prussian blue deposited carbon nanofiber electrode

Prussian blue (PB) analog (NiFe, CoFe, FeFe, and commercial(cPB)) decorated carbon nanofiber (CNF) electrodes were synthesized by the drop casting method in this study to investigate the interaction between PB and CNF for the electrochemical adsorption (EA) and electrochemical desorption (ED) of Cs ion (Cs⁺). The adhesion of PB on the electrode and the EA and ED of Cs⁺ were substantially higher when the CNF electrode was used, compared with the fluorine-doped tin oxide supporting electrode. The use of CNF led to the smooth occurrence of EA and ED of Cs⁺, where the reported efficiency was: NiFe > FeFe > cPB. The EA and ED of Cs⁺ on NiFe decorated CNF (C-NiFe) were strongly affected by the loading amount of NiFe. Although the strongest EA capacity was identified when 1 mg of NiFe was used, it decreased as the loading amount of NiFe increased. Thus, the EA of Cs⁺ occurs under the reduction of NiFe with some Fe(III) reduced to Fe(II) of NiFe, thus inducing more adsorption of Cs⁺. Overall, we confirmed that the C-NiFe electrode with appropriate thickness of NiFe layer is potentially an excellent adsorbent for Cs removal.

Ultrasensitive electrochemical sensor for the detection of carbamazepine based on gadolinium vanadate nanostructure decorated functionalized carbon nanofiber nanocomposite

The gadolinium vanadate nanostructure decorated functionalized carbon nanofiber (GdVO₄/f-CNF) nanocomposite was prepared by the hydrothermal method, which is fabricated on a glassy carbon electrode (GCE) for the determination of carbamazepine (CBZ). The structural morphology of the hydrothermally synthesized GdVO₄/f-CNF material was investigated by several spectroscopy methods such as FESEM, HRTEM, EDS-mapping, XRD, XPS, and Raman. Moreover, the electrical conductivity of our synthesized material was inspected by the electrochemical impedance spectroscopy (EIS) analysis, and the electrochemical performance towards CBZ was inspected by the cyclic voltammetry (CV) and amperometry (AMP) analysis under optimized conditions. The AMP determination of CBZ exhibits the lowest level LOD of 0.0018 μM and a good linear range of 0.01-157 μM. Additionally, our proposed sensor was used to determine the CBZ in the pharmaceutical and, human urine samples which have exposed the acceptable recoveries.

Electrochemical detection of nicotine at a carbon Nanofiber-Poly(amidoamine) dendrimer modified glassy carbon electrode

Development of electrochemical sensors for important drugs such nicotine (an addictive drug) is important for the society. This study reports the electrochemical detection of nicotine at a carbon nanofiber/poly (amidoamine) dendrimer modified glassy carbon electrode. The carbon nanofiber (CNF) modified GCE was prepared by drop-coating followed by the electrodeposition of generation 4 poly (amidoamine) succinamic acid dendrimer (PAMAM) to form the sensor - CNF-PAMAM GCE. Characterization of prepared materials and modified electrodes was carried out using Fourier transmission infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The CNF-PAMAM composite was confirmed by microscopy. A marked reduction in charge transfer resistance and increase in current of the CNF-PAMAM GCE in comparison to the bare electrode showed a synergic improvement electrochemical response because of the CNF-PAMAM nanocomposite. The CNF-PAMAM demonstrated an enhanced performance in the oxidation of nicotine in comparison to the bare GCE by shifting the anodic potential E_pa of nicotine from 0.9 V to 0.8 V. The electrochemical sensor achieved a detection limit (LOD) of 0.02637 μM in the concentration range of 0.4815-15.41 μM of nicotine in 0.1 M PBS at pH 7.5. The sensor ability to determine nicotine in real samples was assessed in cigarettes obtaining recovery percentages of 88.00 and 97.42%. The sensor demonstrated selectivity toward nicotine in the presence of interferences. Finally, the method was validated by ultraviolet-visible spectroscopy analysis.

Dual structure engineering of SiOx-acrylic yarn derived carbon nanofiber based foldable Si anodes for low-cost lithium-ion batteries

Silicon (Si) is attracted much attention due to its outstanding theoretical capacity (4200 mAh/g) as the anode of lithium-ion batteries (LIBs). However, the large volume change and low electron/ion conductivity during the charge and discharge process limit the electrochemical performance of Si-based anodes. Here we demonstrate a foldable acrylic yarn-based composite carbon nanofiber embedded by Si@SiO_x particles (Si@SiO_x-CACNFs) as the anode material. Since the amorphous SiO_x and carbon (C) coating on the outside of the Si particles can provide a double buffer for volume expansion while reducing the contact between the Si core and the electrolyte to form a thin and stable solid electrolyte interface (SEI) film. Simultaneous in-situ electrochemical impedance spectroscopy (in-situ EIS) and galvanostatic intermittent titration technique (GITT) tests show that SiO_x and C have higher ion/electron transport rates, and in addition, using acrylic fiber yarn and Zn(Ac)₂ as raw materials reduces the manufacturing cost and enhanced mechanical properties. Therefore, the half-cell can achieve a high initial Coulombic efficiency (ICE) of 82.3% and a reversible capacity of 1358.2 mAh/g after 180 cycles. It can return to its original shape and remain intact after four consecutive folds, and the soft-pack full battery can also light up LED lights under different bending conditions.

Nanoscale geometry determines mechanical biocompatibility of vertically aligned nanofibers

Vertically aligned carbon nanofibers (VACNFs) are promising material candidates for neural biosensors due to their ability to detect neurotransmitters in physiological concentrations. However, the expected high rigidity of CNFs could induce mechanical mismatch with the brain tissue, eliciting formation of a glial scar around the electrode and thus loss of functionality. We have evaluated mechanical biocompatibility of VACNFs by growing nickel-catalyzed carbon nanofibers of different lengths and inter-fiber distances. Long nanofibers with large inter-fiber distance prevented maturation of focal adhesions, thus constraining cells from obtaining a highly spread morphology that is observed when astrocytes are being contacted with stiff materials commonly used in neural implants. A silicon nanopillar array with 500 nm inter-pillar distance was used to reveal that this inhibition of focal adhesion maturation occurs due to the surface nanoscale geometry, more precisely the inter-fiber distance. Live cell atomic force microscopy was used to confirm astrocytes being significantly softer on the long Ni-CNFs compared to other surfaces, including a soft gelatin hydrogel. We also observed hippocampal neurons to mature and form synaptic contacts when being cultured on both long and short carbon nanofibers, without having to use any adhesive proteins or a glial monoculture, indicating high cytocompatibility of the material also with neuronal population. In contrast, neurons cultured on a planar tetrahedral amorphous carbon sample showed immature neurites and indications of early-stage apoptosis. Our results demonstrate that mechanical biocompatibility of biomaterials is greatly affected by their nanoscale surface geometry, which provides means for controlling how the materials and their mechanical properties are perceived by the cells. STATEMENT OF SIGNIFICANCE: Our research article shows, how nanoscale surface geometry determines mechanical biocompatibility of apparently stiff materials. Specifically, astrocytes were prevented from obtaining highly spread morphology when their adhesion site maturation was inhibited, showing similar morphology on nominally stiff vertically aligned carbon fiber (VACNF) substrates as when being cultured on ultrasoft surfaces. Furthermore, hippocampal neurons matured well and formed synapses on these carbon nanofibers, indicating high biocompatibility of the materials. Interestingly, the same VACNF materials that were used in this study have earlier also been proven to be capable for electrophysiological recordings and sensing neurotransmitters at physiological concentrations with ultra-high sensitivity and selectivity, thus providing a platform for future neural probes or smart culturing surfaces with superior sensing performance and biocompatibility.

Enhanced Pb(II) removal from water using conductive carbonaceous nanomaterials as bacterial scaffolds: An experimental and modelling approach

This study investigated the abilities of electrochemically active bacteria (EAB) as bio-catalysts for Pb(II) bioreduction in an attached growth reactor. Electrically conductive carbon nanofibers (CNF) were used as bacterial scaffolds to facilitate electron transfer between EAB and Pb(II). Our results demonstrated that the CNF attached growth reactor can remove > 80% and > 90% of Pb(II) from solution at 0.5 mg/L and 5.0 mg/L concentrations, respectively, and maintained Pb(II) levels < 0.10 mg/L over repeated Pb(II) dosages dosed at all concentrations. Experimental measurements by SEM-EDX and ICP-OES provided evidence that Pb(II) was reduced to Pb⁰, suggesting that Pb(II) was adsorbed onto CNFs, and subsequently bioreduced. Numerical modelling was used to estimate Pb(II) concentrations along the CNFs via capturing Pb(II)'s diffusive transport, and the removal mechanisms governed by EAB and CNF adsorption. The model simulation results demonstrated that Pb(II) bioreduction was dominant in the reactor and the significance of Monod kinetics, biofilm thickness and Pb(II) dosage concentration on its removal. This study is the first to prove EAB's ability to treat Pb(II) from contaminated waters in an attached growth configuration. The findings here demonstrate that CNFs can boost biological treatment efficacies in wastewater and/or water treatment to meet stringent water guidelines.

Hydrophobic and porous carbon nanofiber membrane for high performance solar-driven interfacial evaporation with excellent salt resistance

Interfacial evaporation has recently received great interest from both academia and industry to harvest fresh water from seawater, due to its low cost, sustainability and high efficiency. However, state-of-the-art solar absorbers usually face several issues such as weak corrosion resistance, salt accumulation and hence poor long-term evaporation stability. Herein, a hydrophobic and porous carbon nanofiber (HPCNF) is prepared by combination of the porogen sublimation and fluorination. The HPCNF possessing a macro/meso porous structure exhibits large contact angles (as high as 145°), strong light absorption and outstanding photo-thermal conversion performance. When the HPCNF is used as the solar absorber, the evaporation rate and efficiency can reach up to 1.43 kg m^-2h^-1 and 87.5% under one sunlight irradiation, respectively. More importantly, the outstanding water proof endows the absorber with superior corrosion resistance and salt rejection performance, and hence the interfacial evaporation can maintain a long-term stability and proceed in a variety of complex conditions. The HPCNFs based interfacial evaporation provides a new avenue to the high efficiency solar steam generation.

Cytotoxicity of three graphene-related materials in rainbow trout primary hepatocytes is not associated to cellular internalization

As a consequence of increasing production and use of graphene-related materials (GRM), their release into the aquatic environment is likely to be expected. Development of appropriate model systems to assess their potential toxicity toward aquatic organisms is undoubtedly needed. Of particular relevance are primary cultures of fish hepatocytes, since they maintain similar functionalities as those of the original tissue. Isolated hepatocytes from rainbow trout (Oncorhynchus mykiss) were exposed to ranges of concentrations of different forms of GRM, two graphene oxides (GO) of sheet-like structure and one tubular-shaped carbon nanofiber (CNF) in the presence or absence of fetal bovine serum (FBS) for 24 and 72 h. Metabolic activity, cell membrane integrity, lysosomal function, reactive oxygen species (ROS) formation and interaction with cytochrome P450 1 A enzyme were assessed by using AlamarBlue, 5-carboxyfluorescein diacetate-acetoxymethyl ester, neutral red uptake, dichlorofluorescein and 7-ethoxyresorufin-O-deethylase (EROD) assays, respectively. In the presence of FBS, GO affected metabolic activity and cell membrane integrity more than CNF, whilst absence of serum further reduced cell viability in GRM-exposed cells. GRM did not alter lysosomal function nor did it induce ROS formation or EROD activity. Intracellular uptake was observed only in the case of CNF when incubated without FBS. Primary hepatocytes from rainbow trout appear to be a suitable model to screen for cytotoxicity and to reveal any interaction with GRM. Results emphasize the role of serum proteins in the toxicological responses following exposure to GRM with important implications for the environmental risk assessment of these nanomaterials.

Heterogeneous cobalt polysulfide leaf-like array/carbon nanofiber composites derived from zeolite imidazole framework for advanced asymmetric supercapacitors

Developing new electrode materials is one of the keys to improving the energy density of supercapacitors. In this article, a novel cobalt polysulfide/carbon nanofibers (C,N-Co_xS_y/CNF) film derived from zeolitic imidazolate framework is first prepared by a facile strategy. The composite material with two-dimensional leaf-shaped nanoarray neatly grown on the surface of carbon nanofibers is composed of CoS, CoS₂, Co₉S₈, N-doped carbon nanosheets, and carbon nanofibers. It is found that the composite can not only increase the contact area with the electrolyte but also provide abundant redox-active sites and a Faraday capacitance for the entire electrode. The C,N-Co_xS_y/CNF composite exhibits excellent electrochemical properties, including a high capacity of up to 1080F g ^-1 at 1 A g ^-1 and a good rate capability (80.4 % from 1 A g ^-1 to 10 A g ^-1). A C,N-Co_xS_y/CNF//AC asymmetric supercapacitor device is assembled using C,N-Co_xS_y/CNF as the positive electrode and activated carbon as the negative electrode, showing high energy density (37.29 Wh kg ^-1@813.6 W kg ^-1) and good cycle stability (90.5% of initial specific capacitance at 10 g^-1 after 5000 cycles). This C,N-Co_xS_y/CNF composite material may also be used as a potential electrode for future lithium-ion batteries, zinc-ion batteries, lithium-sulfur batteries, etc.

rGO based immunosensor amplified using MWCNT and CNF nanocomposite as analytical tool for CA125 detection

The electrochemical performance of dual layer immunosensor has been studied by employing reduced Graphene oxide (rGO) and its nanocomposites with Carbon Nanofibers (CNFs) and Carbon Nanotubes (CNTs) as supporting matrix for the detection of CA125. The immunosensor determination was based on the formation of antibody - antigen immunocomplex, a decrement in the current response was observed in accordance with the concentration of antigen. Better performance exhibited by rGO/CNF in terms of linearity (99%) and sensitivity 0.65 μA (μg mL^-1)^-1 can be attributed to its conductivity and surface area. The nanocomposite are employed in the detection of CA125 with linear working range of 10-32 × 10^-4 μg mL^-1, the limit of detection is found to be 0.28 pg mL^-1 rGO nanocomposite with CNT (rGO/CNT) is studied as transducer material. rGO/CNT exhibited better linearity when compared to rGO due to its good conductivity. Thus, graphene nanocomposite transducer materials have vital application in detection of oncomarkers.

Iron nanoparticles decorated hierarchical carbon fiber forest for the magnetic solid-phase extraction of multi-pesticide residues from water samples

This study describes a versatile, robust and fast sample pre-concentration novel method based on chemical vapour deposition grown iron nanoparticles dispersed hierarchical carbon fiber forest (Fe-ACF/CNF) for the determination of multi-pesticide residue in water samples. This method was developed by the implementation of Fe-ACF/CNF to magnetic solid-phase extraction method (MSPE) for the adsorption of twenty-nine pesticides of various classes using gas chromatography equipped with an electron capture detector. Fe-ACF/CNF was grown via tip growth mechanism and Fe-nanoparticles are moved to the tip of CNF. The presence of Fe-nanoparticles is responsible for the magnetic property of proposed adsorbents. The Fe-ACF/CNF is competent enough to extract twenty-nine pesticides of different physico-chemical characteristics from water samples. All the predominant parameters including the amount of sorbent desorption time, temperature, sonication effect, regeneration, and reusability of Fe-ACF/CNF were thoroughly investigated. Acceptable linearity was obtained in the range of 20-500 μg/L with a correlation coefficient value ≥ 0.990 for all pesticides. The accuracy of the developed method was evaluated and the obtained recovery of the spiked samples was within 70-120% (standard deviation ≤ 15%) and reusability up to the 4th cycle. The limit of detection and quantification values was in the range of 1.44-5.15 and 4.76-17.0 μg/L, respectively. The obtained results are also cross verified with real water samples from the Gomti river (Lucknow, India) and shown the excellent extraction efficiency of Fe-ACF/CNF.

Construction of ZIF@electrospun cellulose nanofiber derived N doped metallic cobalt embedded carbon nanofiber composite as binder-free supercapacitance electrode

In this study, binder-free hybrid supercapacitance electrode based on N, Co co-doped porous carbon polyhedral encapsulated carbon nanofibers composites (N-Co/CNF) was prepared through pyrolyzing cobalt based zeolitic imidazolate frameworks (ZIF-67(Co)) incorporated electrospun cellulose nanofibers. With rational combination of the conductivity provided by cellulose derived CNF, promising porosity provided by CNF and ZIF-67(Co) derived porous carbon and uniformly dispersed metallic cobalt nanoparticles, the N-Co/CNF displayed excellent electrochemical properties. Specifically, the N-Co/CNF pyrolyzed at 800 °C possessed superior electrochemical performance in 1 M H₂SO₄ electrolyte, including a specific capacitance of ~433 F/g and 84% of the capacitance retention after 3000 consecutive charge-discharge cycles. This significantly exceeded the performance of cellulose derived CNF based pure carbonaceous electrode. Therefore, the present study provides a new view on the construction of high performance hybrid supercapacitance electrode which introduces renewable biomass resources like cellulose as both carbonaceous material precursors and conductive binders.

Determination of chloramphenicol and tetracycline residues in milk samples by means of nanofiber coated magnetic particles prior to high-performance liquid chromatography-diode array detection

A magnetic solid phase extraction (MSPE) coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD) methodology was developed for the determination of chloramphenicol (CP) and tetracycline (TET) antibiotic residues in milk samples. As a solid phase sorbent, C-nanofiber coated magnetic nanoparticles were synthesized and extensively characterized using Field Emission Scanning Electron Microscopy (FE-SEM), Raman Spectroscopy and X-ray Powder Diffraction (XRD) analysis. Experimental variables of MSPE method for both antibiotic analytes were investigated and optimized systematically. After MSPE, the linear range for both the analytes (r² > 0.9954) were obtained in a range 10.0-600.0 ng mL^-1. The limit of detections (LODs) for CP and TET were 3.02 and 3.52 ng mL^-1, respectively while RSDs % were below than 4.0%. Finally, the developed method based on MPSE-HPLC-DAD was applied to real milk samples to quantify the antibiotic residues. Recovery values for each antibiotic compound were found in the range of 94.6-105.4% (n = 3) by using spiked model solution.

Magnetic carbon nanofiber composite adsorbent through green in-situ conversion of bacterial cellulose for highly efficient removal of bisphenol A

A magnetic carbon nanofiber sorbent was facilely synthesized from bio-based bacterial cellulose and FeCl₃via impregnation, freeze-drying, followed by pyrolysis at 700 °C, without additional activation or nanofiber fabrication. The obtained material possessed intrinsic 3D naturally fibrous and porous structure with good magnetization. The adsorption results showed that the adsorption capacity of the prepared adsorbent towards bisphenol A (BPA) was as high as 618 mg/g, outperforming other adsorbents. Moreover, recycling the adsorbent for 10 consecutive cycles retained 96% of initial adsorption efficiency. The magnetic sorbent can maintain good magnetic properties even with recycling. Hence, the use of bacterial cellulose as a renewable carbon nanofiber precursor and FeCl₃ as a source of magnetic particles, and a green pore generating agent in the present protocol, lead to a superior magnetic carbon nanofiber adsorbent with sustainable characteristics.

Electro-conductive carbon nanofibers containing ferrous sulfate for bone tissue engineering

The application of electroactive scaffolds can be promising for bone tissue engineering applications. In the current paper, we aimed to fabricate an electro-conductive scaffold based on carbon nanofibers (CNFs) containing ferrous sulfate. FeSO₄·7H₂O salt with different concentrations 5, 10, and 15 wt%, were blended with polyacrylonitrile (PAN) polymer as the precursor and converted to Fe₂O3/CNFs nanocomposite by electrospinning and heat treatment. The characterization was conducted using SEM, EDX, XRD, FTIR, and Raman methods. The results showed that the incorporation of Fe salt induces no adverse effect on the nanofibers' morphology. EDX analysis confirmed that the Fe ions are uniformly dispersed throughout the CNF mat. FTIR spectroscopy showed the interaction of Fe salt with PAN polymer. Raman spectroscopy showed that the incorporation of FeSO4·7H₂O reduced the ID/IG ratio, indicating more ordered carbon in the synthesized nanocomposite. Electrical resistance measurement depicted that, although the incorporation of ferrous sulfate reduced the electrical conductivity, the conductive is suitable for electrical stimulation. The in vitro studies revealed that the prepared nanocomposites were cytocompatible and only negligible toxicity (less than 10%) induced by CNFs/Fe₂O₃ fabricated from PAN FeSO₄·7H₂O 15%. Although various nanofibrous composite fabricated with Fe NPs have been evaluated for tissue engineering applications, CNFs exhibited promising properties, such as excellent mechanical strength, biocompatibility, and electrical conductivity. These results showed that the fabricated nanocomposites could be applied as the bone tissue engineering scaffold.

Sulfur-Induced Growth of Coordination Polymer Derived-Straight Carbon Nanotubes on Carbon Nanofiber Network for Zn-Air Batteries

Low-cost heteroatom-doped carbon nanomaterials have been widely studied for efficient oxygen reduction reaction and energy storage and conversion in metal-air batteries. A Masson pine twigs-like 3-dimensional network construction of carbon nanofibers (CNFs) with abundant straight long Co, N, and S-doped carbon nanotubes (CNTs) is developed by thermal treatment of Co-based polymer coated onto polyacrylonitrile nanofiber network together with thiourea at 900 °C, denoted as CNFT-Co₉ S₈ -900. It is interesting to note that the introduction of a high concentration of sulfur does not lead to the complete toxicity of catalysts, but promotes the axial growth to selectively form straight CNTs instead of curly bamboo-like CNTs. The highly graphitized in-situ grown Co, N, S-doped CNTs and the 3-dimensional N-doped CNF network provide both active catalytic sites and highly conductive paths, which are beneficial for oxygen reduction reaction (ORR). Thus, the optimal CNFT-Co₉ S₈ -900 performs the excellent ORR catalytic activity with a half-wave potential of 0.84 V and a diffusion-limited current density of 5.49 mA cm^-2 . Furthermore, the CNFT-Co₉ S₈ -900-based Zn-air devices also possess a high power density of 136.9 mW cm^-2 better than commercial Pt/C.

Monitoring the mechanism of anti-cancer agents to inhibit colorectal cancer cell proliferation: Enzymatic biosensing of glucose combined with molecular docking

Glucose, a major energy source in cellular metabolism, has a significant role in cell growth. The increase in glucose uptake is a distinguishing hallmark in cancer cells. A key step in glucose utilization is the transport of glucose to the cancer cells for supplying their additional energy. The glucose transporter (or GLUT) family is a membrane protein which facilitates the uptake of glucose in most cancer cell types. Given the increased glucose level in cancer cells and the regulatory role of GLUTs in glucose uptake, it is required to combine both experimental and theoretical studies to develop new methods to monitor cell proliferation. Herein, for the first time, a new strategy was proposed to evaluate the cell proliferation of HT-29 based on glucose consumption in the presence of resveratrol (RSV) as an anticancer agent. A hybrid nanocomposite of carbon nanofibers and nitrogen-doped graphene quantum dots was used to design an enzymatic sensor for the selective and sensitive determination of glucose in cancer cells. The results obtained from the voltammetric technique were compared with the conventional colorimetric assay. A good correlation was observed between the proliferation rate and glucose utilization by cancer cells. As it was observed, RSV induces a decrease in glucose consumption, indicating lower glucose uptake efficiency for HT-29 cells. Molecular docking studies reveal that RSV can block the interaction of glucose with the GLUT family. This is one of the possible mechanisms for the decrease of glucose level followed by the reduction of cell proliferation in the presence of RSV. Compared with traditional methods, in vitro electrochemical techniques benefit from simple, nontoxic, sensitive and low-cost detection assays and hence serve as a novel tool to pursue the growth inhibition of cancer cell in response to anti-cancer agents.

A facile method for the fabrication of hierarchically structured Ni2CoS4 nanopetals on carbon nanofibers to enhance non-enzymatic glucose oxidation

Unique Ni₂CoS₄-carbon nanofiber (CNF) composite nanostructures were fabricated using a simple electrospinning-assisted hydrothermal route and used for the rapid and accurate electrochemical oxidation of glucose in real samples at the trace level. Electrochemical impedance spectroscopy and cyclic voltammetry of unmodified and modified electrodes revealed low charge-transfer resistance and the excellent electrocatalytic sensing of glucose when using the Ni₂CoS₄-CNF at a low potential due to the combined benefits of the highly conductive Ni₂Co₂S₄ anchored to the large surface area of the CNFs. Amperometric analysis of the fabricated sensor has shown an extremely low limit of detection (0.25 nM) and a large linear range (5-70 nM) for glucose at a working potential of 0.54 V (vs. Hg/HgO). The practicability of the Ni₂CoS₄-CNF for use in glucose determination was tested withl human saliva, blood plasma, and fruit juice samples. The Ni₂CoS₄-CNF/GCE showed acceptable recovery values for human saliva (99.1-100.8%), blood plasma (98.6-101.5%), and fruit juice (95.1-105.7%) samples. The proposed sensor also exhibited outstanding electroanalytical characteristics for glucose oxidation in these samples, including reusability, repeatability, and interference resistance, even in the presence of other biological substances and organic and inorganic metal ions.

On the bacteriostatic activity of hyaluronic acid composite films

Biofilm-related infections and contamination of biomaterials are major problems in the clinic. These contaminations are frequently caused by Staphylococcus aureus and are a pressing issue for implantable devices, catheters, contact lenses, prostheses, and wound dressings. Strategies to decrease contamination and biofilm related infections are vital for the success of implantable biomaterials. In this context, hyaluronic acid (HA), a naturally derived carbohydrate polymer, known to be biocompatible, degradable, and immunomodulatory, has shown some antimicrobial activity effects. Due to its poor structural stability, crosslinking strategies, and the incorporation of reinforcing fibres in HA gels is required to produce tailored gels for varying applications. Whilst carbon-based reinforcing materials, such as carbon nanofibers (CNF), present some intrinsic antimicrobial activity related to their high surface area, herein, a crosslinking strategy to enhance the mechanical properties and regulate the rate of degradation of HA is presented. We utilise bis-(β-isocyanatoethyl) disulphide (BIED) as the crosslinker with the gel reinforced using 0.25 wt% CNF. The effects of CNF and BIED on the structural, mechanical, thermal, and swelling behaviour are examined. These new HA derivatives exhibit excellent mechanical properties and are capable of withstanding physiological stresses in vivo. Antimicrobial activity of the HA derivatives were tested against Staphylococcus aureus and the results reveal antibacterial effect. These carbohydrate based materials have potential application on surfaces within clinical settings where staphylococcal contamination is currently an issue.

Polyacrylonitrile-based carbon nanofibers as a matrix for laser desorption/ionization time-of-flight mass spectrometric analysis of small molecules under both positive and negative ionization modes

Carbon fiber (CNF), prepared by carbonization of electrospun polyacrylonitrile (PAN) fibers, is systematically investigated as a mediator to replace conventional organic matrices for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS). CNF exhibits a high salt tolerance, sensitivity, and resolution for organic matrix-free laser desorption/ionization time-of-flight mass spectrometry (LDI-MS) analysis of various analytes under both positive and negative ionization modes. Especially, saccharides, a neutral molecule having low negative ionization efficiency, are successfully detected with CNF. Taken together, this study clearly demonstrates CNF is a promising material to develop an efficient and universal platform for LDI-MS analysis regardless of preferential ionization modes of analytes. Graphical abstract.

Heterogeneous activation of persulfate by carbon nanofiber supported Fe3O4@carbon composites for efficient ibuprofen degradation

Heterogeneous catalysts for persulfate activation were synthesized using ferrocene and carbon nanofiber as precursor by one-pot hydrothermal method and their performances of catalysts for persulfate activation were evaluated via ibuprofen degradation efficiencies. The structure of the catalyst was identified as carbon encapsulated Fe₃O₄ grafted on carbon nanofibers (Fe₃O₄@C/CNFs) by multiple characterization methods. The CNF supporter could greatly reduce the magnetization of Fe₃O₄ and increase the coercivity, which effectively avoided agglomeration. The specific surface area of the Fe₃O₄@C/CNFs was determined as 65.36 m²/g. The Fe₃O₄@C/CNFs exhibited high catalytic performances for persulfate activation and ibuprofen could be completely removed in the system with an activation energy of 23.51 kJ/mol. The degradation efficiencies increased with the Fe loading, catalyst dosage and persulfate concentration. The catalysts also showed stable activity with minimal metal leaking over five cycles. Hydroxyl and sulfate radicals were verified by spin-trapping and scavenger experiments and principally contributed to ibuprofen degradation. The possible ibuprofen degradation pathways were elucidated based on intermediate analysis. This work would promote the applications of sulfate radical based advanced oxidation processes for the environmental remediation.

Simultaneous energy harvest and nitrogen removal using a supercapacitor microbial fuel cell

The insufficient removal of pollutants and bioelectricity production have become a bottleneck for high-concentration saline wastewater treatment through microbial fuel cell (MFC) technology. Herein, a novel supercapacitor MFC (SC-MFC) was constructed with carbon nanofibers composite electrodes to investigate pollutant removal ability, power generation, and electrochemical properties using real landfill leachate. The possible extracellular electron transfer and nitrogen element conversion pathways in the bioanode were also analyzed. Results showed that the SC-MFC had higher pollutant removal rates (COD: 59.4 ± 1.2%; NH₄⁺-N: 78.2 ± 1.6%; and TN: 77.8 ± 1.2%), smaller internal impedance R_t (∼6 Ω), higher exchange current density i₀ (2.1 × 10^-4 A cm^-2), and a larger catalytic current j₀ (704 μA cm^-2) with 60% leachate than those with 10% and 20% leachate, resulting in a power output of 298 ± 22 mW m^-2. Ammonium could be incorporated by chemoautotrophic bacteria to produce organic compounds that could be further utilized by heterotrophs to generate power when biodegradable organic matters are depleted. Three conversion pathways of nitrogen might be involved, including NH₄⁺ diffusion from anode to cathode chamber, nitrification, and the denitrification process. Additionally, cyclic voltammetry tests showed that both the direct electron transfer (DET) and the mediator electron transfer in bioanode were involved and dominated by DET. The microbial analysis revealed that the bioanode was dominated by salt-tolerant denitrifying bacteria (38.5%), which was deduced to be the key functional microorganism. The electrochemically active bacteria decreased significantly from 61.7% to 4% over three stages of leachate treatment. Overall, the SC-MFC has demonstrated the potential for wastewater treatment along with energy harvesting and provides a new avenue toward sustainable leachate management.

Carbon nanomaterial-derived lung burden analysis using UV-Vis spectrophotometry and proteinase K digestion

BACKGROUND

The quantification of nanomaterials accumulated in various organs is crucial in studying their toxicity and toxicokinetics. However, some types of nanomaterials, including carbon nanomaterials (CNMs), are difficult to quantify in a biological matrix. Therefore, developing improved methodologies for quantification of CNMs in vital organs is instrumental in their continued modification and application.

RESULTS

In this study, carbon black, nanodiamond, multi-walled carbon nanotube, carbon nanofiber, and graphene nanoplatelet were assembled and used as a panel of CNMs. All CNMs showed significant absorbance at 750 nm, while their bio-components showed minimal absorbance at this wavelength. Quantification of CNMs using their absorbance at 750 nm was shown to have more than 94% accuracy in all of the studied materials. Incubating proteinase K (PK) for 2 days with a mixture of lung tissue homogenates and CNMs showed an average recovery rate over 90%. The utility of this method was confirmed in a murine pharyngeal aspiration model using CNMs at 30 μg/mouse.

CONCLUSIONS

We developed an improved lung burden assay for CNMs with an accuracy > 94% and a recovery rate > 90% using PK digestion and UV-Vis spectrophotometry. This method can be applied to any nanomaterial with sufficient absorbance in the near-infrared band and can differentiate nanomaterials from elements in the body, as well as the soluble fraction of the nanomaterial. Furthermore, a combination of PK digestion and other instrumental analysis specific to the nanomaterial can be applied to organ burden analysis.

Conductive carbon nanofibers incorporated into collagen bio-scaffold assists myocardial injury repair

Currently, treatment of myocardial infarction considered as unmet clinical need. Nanomaterials have been used in the regeneration of tissues such as bone, dental and neural tissue in the body and have increased hope for revitalizing of damaged tissues. Conductive carbon base nanomaterials with its superior physicochemical properties have emerged as promising materials for cardiovascular application. In this study, we applied a biosynthetic collagen scaffold containing carbon nanofiber for regenerating of damaged heart tissue. The collagen-carbon nanofiber scaffold was fabricated and fully characterised. The scaffold was grafted on the affected area of myocardial ischemia, immediately after ligation of the left anterior descending artery in the wistar rat's model. After 4 weeks, histological analyses were performed for investigation of formation of immature cardio-myocytes, epicardial cells, and angiogenesis. Compared to untreated hearts, this scaffold significantly protects heart tissue against injury. This improvement is accompanied by a reduction in fibrosis and the increased formation of a blood vessel network and immature cardio-myocytes in the infarction heart. No toxicity detected with apoptotic and TUNEL assays. In conclusion, the mechanical support of the collagen scaffold with carbon nanofiber enhanced the regeneration of myocardial tissue.

An amperometric biosensor based on poly(L-aspartic acid), nanodiamond particles, carbon nanofiber, and ascorbate oxidase-modified glassy carbon electrode for the determination of L-ascorbic acid

An amperometric L-ascorbic acid biosensor utilizing ascorbate oxidase (AOx) immobilized onto poly(L-aspartic acid) (P(L-Asp)) film was fabricated on carbon nanofiber (CNF) and nanodiamond particle (ND)-modified glassy carbon electrode (GCE). Effects of AOx, ND, and CNF amounts were investigated by monitoring the response currents of the biosensor at different amounts of AOx, ND, and CNF. The electropolymerization step of L-aspartic acid on CNF-ND/GCE surface was also optimized. Scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques were used to enlighten the modification steps of the biosensor. The effects of pH and applied potential were studied in detail to achieve the best analytical performance. Under optimized experimental conditions, the AOx/P(L-Asp)/ND-CNF/GCE biosensor showed a linear response to L-ascorbic acid in the range of 2.0 × 10^-7-1.8 × 10^-3 M with a detection limit of 1.0 × 10^-7 M and sensitivity of 105.0 μAmM^-1 cm^-2. The novel biosensing platform showed good reproducibility and selectivity. The strong interaction between AOx and the P(L-Asp)/ND-CNF matrix was revealed by the high repeatability (3.4%) and good operational stability. The AOx/P(L-Asp)/ND-CNF/GCE biosensor was successfully applied to the determination of L-ascorbic acid in vitamin C effervescent tablet and pharmaceutical powder containing ascorbic acid with good results, which makes it a promising approach for quantification of L-ascorbic acid. Graphical abstract.

Two-Step and Green Synthesis of Highly Fluorescent Carbon Quantum Dots and Carbon Nanofibers from Pine Fruit

To green synthesis of highly yield photoluminescence carbon nanofibers/carbon quantum dots by pine fruit the ball milling assisted hydrothermal method was served. Different analysis such as XRD, EDS, elemental mapping and FT-IR analysis were used to study the product structure. The optical properties of the synthesized carbon nanomaterials were investigated by UV-Vis and PL analysis. Also, the effects of hydrothermal time and temperature on the PL intensity were studied. To study the product size and morphology SEM and TEM analysis were served. Also, the nucleation and growth mechanism was studied by TEM images. The results showed the product is composed of very tiny nitrogen-doped carbon dots and carbon nanofibers with high photoluminescence intensity. The photocatalytic activity of the product was investigated by degradation of six dyes namely Acid blue, Eosin Y, Erichrome Black T, Methylene blue, Methyl orange and Methyl. The results showed the product has high photocatalytic activity and it can degrade the dyes with creation reactive oxide species in the aqueous solution. The surface activity of the product was also investigated and it was found it can adsorb Pb²⁺ and Cd²⁺ from the water with 100% efficiency. The results showed we can synthesis of useful carbon nanomaterials with high photoluminescence intensity, highly photocatalytic activity and surface adsorption via a simple and fast method with the pine fruit. Graphical abstract.

Atomic layer deposition of Pd nanoparticles on self-supported carbon-Ni/NiO-Pd nanofiber electrodes for electrochemical hydrogen and oxygen evolution reactions

The most critical challenge in hydrogen fuel production is to develop efficient, eco-friendly, low-cost electrocatalysts for water splitting. In this study, self-supported carbon nanofiber (CNF) electrodes decorated with nickel/nickel oxide (Ni/NiO) and palladium (Pd) nanoparticles (NPs) were prepared by combining electrospinning, peroxidation, and thermal carbonation with atomic layer deposition (ALD), and then employed for hydrogen evolution and oxygen evolution reactions (HER/OER). The best CNF-Ni/NiO-Pd electrode displayed the lowest overpotential (63 mV and 1.6 V at j = 10 mA cm^-2), a remarkably small Tafel slope (72 and 272 mV dec^-1), and consequent exchange current density (1.15 and 22.4 mA cm^-2) during HER and OER, respectively. The high chemical stability and improved electrocatalytic performance of the prepared electrodes can be explained by CNF functionalization via Ni/NiO NP encapsulation, the formation of graphitic layers that cover and protect the Ni/NiO NPs from corrosion, and ALD of Pd NPs at the surface of the self-supported CNF-Ni/NiO electrodes.

A novel polycaprolactone/carbon nanofiber composite as a conductive neural guidance channel: an in vitro and in vivo study

The current study aimed to investigate the potential of carbon nanofibers to promote peripheral nerve regeneration. The carbon nanofiber-imbedded scaffolds were produced from polycaprolactone and carbon nanofibers using thermally induced phase separation method. Electrospinning technique was utilized to fabricate polycaprolactone/collagen nanofibrous sheets. The incorporation of carbon nanofibers into polycaprolactone's matrix significantly reduced its electrical resistance from 4.3 × 109 ± 0.34 × 109 Ω to 8.7 × 104 ± 1.2 × 104 Ω. Further in vitro studies showed that polycaprolactone/carbon nanofiber scaffolds had the porosity of 82.9 ± 3.7% and degradation rate of 1.84 ± 0.37% after 30 days and 3.58 ± 0.39% after 60 days. The fabricated scaffolds were favorable for PC-12 cells attachment and proliferation. Neural guidance channels were produced from the polycaprolactone/carbon nanofiber composites using water jet cutter machine then incorporated with PCL/collagen nanofibrous sheets. The composites were implanted into severed rat sciatic nerve. After 12 weeks, the results of histopathological examinations and functional analysis proved that conductive conduit out-performed the non-conductive type and induced no toxicity or immunogenic reactions, suggesting its potential applicability to treat peripheral nerve damage in the clinic.

High electrochemical performance carbon nanofibers with hierarchical structure derived from metal-organic framework with natural eggshell membranes

Carbon nanofibers with hierarchical structure were synthesized by combining Co-containing zeolitic imidazolate frameworks (ZIF-67) with natural eggshell membranes (ESMs). Benefiting from the hierarchical structure and element modification of Co/N, the obtained nanofibers exhibited excellent oxygen reduction reaction (ORR) performance. The reusing of ESMs trash made this strategy meaningful for environment.

Improved Na+/K+ Storage Properties of ReSe2-Carbon Nanofibers Based on Graphene Modifications

Rhenium diselenide (ReSe₂) has caused considerable concerns in the field of energy storage because the compound and its composites still suffer from low specific capacity and inferior cyclic stability. In this study, ReSe₂ nanoparticles encapsulated in carbon nanofibers were synthesized successfully with simple electrospinning and heat treatment. It was found that graphene modifications could affect considerably the microstructure and electrochemical properties of ReSe₂-carbon nanofibers. Accordingly, the modified compound maintained a capacity of 227 mAh g^-1 after 500 cycles at 200 mA g^-1 for Na⁺ storage, 230 mAh g^-1 after 200 cycles at 200 mA g^-1, 212 mAh g^-1 after 150 cycles at 500 mA g^-1 for K⁺ storage, which corresponded to the capacity retention ratios of 89%, 97%, and 86%, respectively. Even in Na⁺ full cells, its capacity was maintained to 82% after 200 cycles at 1C (117 mA g^-1). The superior stability of ReSe₂-carbon nanofibers benefitted from the extremely weak van der Waals interactions and large interlayer spacing of ReSe₂, in association with the role of graphene-modified carbon nanofibers, in terms of the shortening of electron/ion transport paths and the improvement of structural support. This study may provide a new route for a broadened range of applications of other rhenium-based compounds.

Nanostructured Pd-Based Electrocatalyst and Membrane Electrode Assembly Behavior in a Passive Direct Glycerol Fuel Cell

The aim of this study was to synthesize, characterize, and observe the catalytic activity of Pd₁Au₁ supported by vapor-grown carbon nanofiber (VGCNF) anode catalyst prepared via the chemical reduction method. The formation of the single-phase compounds was confirmed by X-ray diffraction (XRD) and Rietveld refinement analysis, which showed single peaks corresponding to the (111) plane of the cubic crystal structure. Further analysis was carried out by field emission scanning emission microscopy (FESEM), energy dispersive X-ray analysis (EDX), nitrogen adsorption/desorption measurements, and X-ray photoelectron spectroscopy (XPS). The electrochemical performance was examined by cyclic voltammetry tests. The presence of mesoporous VGCNF as support enables the use of a relatively small amount of metal catalyst that still produces an excellent current density (66.33 mA cm^-2). Furthermore, the assessment of the kinetic activity of the nanocatalyst using the Tafel plot suggests that Pd₁Au₁/VGCNF exerts a strong electrocatalytic effect in glycerol oxidation reactions. The engineering challenges are apparent from the fact that the application of the homemade anode catalyst to the passive direct glycerol fuel cell shows the power density of only 3.9 mW cm^-2. To understand the low performance, FESEM observation of the membrane electrode assembly (MEA) was carried out, examining several morphological defects that play a crucial role and affect the performance of the direct glycerol fuel cell.

N, F-Codoped Microporous Carbon Nanofibers as Efficient Metal-Free Electrocatalysts for ORR

Currently, the oxygen reduction reaction (ORR) mainly depends on precious metal platinum (Pt) catalysts. However, Pt-based catalysts have several shortcomings, such as high cost, scarcity, and poor long-term stability. Therefore, development of efficient metal-free electrocatalysts to replace Pt-based electrocatalysts is important. In this study, we successfully prepared nitrogen- and fluorine-codoped microporous carbon nanofibers (N, F-MCFs) via electrospinning polyacrylonitrile/polyvinylidene fluoride/polyvinylpyrrolidone (PAN/PVDF/PVP) tricomponent polymers followed by a hydrothermal process and thermal treatment, which was achieved for the first time in the literature. The results indicated that N, F-MCFs exhibit a high catalytic activity (E_onset: 0.94 V vs. RHE, E_1/2: 0.81 V vs. RHE, and electron transfer number: 4.0) and considerably better stability and methanol tolerance for ORR in alkaline solutions as compared to commercial Pt/carbon (Pt/C, 20 wt%) catalysts. Furthermore, in acidic media, N, F-MCFs showed a four-electron transfer pathway for ORR. This study provides a new strategy for in situ synthesis of N, F-MCFs as highly efficient metal-free electrocatalysts for ORR in fuel cells.

A Novel Flexible Full-Cell Lithium Ion Battery Based on Electrospun Carbon Nanofibers Through a Simple Plastic Package

The paper reports a novel flexible full-cell lithium ion battery (LIB) through a simple plastic package method. Carbon nanofibers (CNFs) are synthesized by electrospinning technology and the subsequent carbonation process. The CNFs with three-dimensional interconnected fibrous nanostructure exhibit a stable reversible capacity of 412 mAh g^-1 after 100 cycles in the half-cell testing. A full cell is assembled by using CNF anode and commercial LiCoO₂ cathode, and it displays good flexibility and lighting LED ability. The aggregate thickness of the constructed full-cell LIB is approximately 500 μm, consisting of a CNFs/Cu film, a separator, a LiCoO₂/Al film, electrolyte, and two polyvinyl chloride (PVC) films. The structure, morphology, and the electrochemical performances of electrospun CNFs and LiCoO₂ electrodes are analyzed in details.

Cobalt ferrite nanoparticles supported on electrospun carbon fiber as a magnetic heterogeneous catalyst for activating peroxymonosulfate

Cobalt ferrite (CF) nanoparticle (NP) represents a promising alternative to Co3O4 NP for peroxymonosulfate (PMS) activation in view of its strong magnetism for easy recovery. As CF NPs in water are prone to agglomerate, a few attempts have been made to immobilize CF NPs on substrates. While carbonaceous supports are more favorable owing to their earth abundancy, the study of carbon-supported CF for PMS activation is limited to graphene-based CF, which, however, requires complicated protocols to prepare. As carbon-supported CF, by straightforward preparation, is still greatly desired, this study aims to employ electrospinning techniques for preparing carbon-supported CF by carbonizing an electrospun CF-embedded polyacrylonitrile (PAN) fiber. After carbonization, the CF-PAN fiber is converted into CF-embedded carbon nanofiber (CF@CNF), which contains well distributed CF NPs, high magnetism and stable carbon support, making CF@CNF a highly promising catalyst for activating PMS. As amaranth decolorization is used as a model reaction, CF@CNF is able to activate PMS for generating sulfate radicals and then decolorize amaranth in water. Amaranth decolorization by CF@CNF-PMS is also substantially facilitated at elevated temperature, and enhanced under the weakly acidic condition. CF@CNF also remains effective to activate PMS even in the presence of salts and surfactants, and re-usable over multiple cycles. Compared to other reported catalysts, CF@CNF also exhibited a much lower Ea value (35.8 kJ/mol) for amaranth decolorization. These features validate that CF@CNF is an advantageous and convenient catalyst for activating PMS.

Carbon nanotube and nanofiber exposure and sputum and blood biomarkers of early effect among U.S. workers

BACKGROUND

Carbon nanotubes and nanofibers (CNT/F) are increasingly used for diverse applications. Although animal studies suggest CNT/F exposure may cause deleterious health effects, human epidemiological studies have typically been small, confined to single workplaces, and limited in exposure assessment.

OBJECTIVES

We conducted an industrywide cross-sectional epidemiological study of 108 workers from 12 U.S. sites to evaluate associations between occupational CNT/F exposure and sputum and blood biomarkers of early effect.

METHODS

We assessed CNT/F exposure via personal breathing zone, filter-based air sampling to measure background-corrected elemental carbon (EC) (a CNT/F marker) mass and microscopy-based CNT/F structure count concentrations. We measured 36 sputum and 37 blood biomarkers. We used factor analyses with varimax rotation to derive factors among sputum and blood biomarkers separately. We used linear, Tobit, and unconditional logistic regression models to adjust for potential confounders and evaluate associations between CNT/F exposure and individual biomarkers and derived factors.

RESULTS

We derived three sputum and nine blood biomarker factors that explained 78% and 67%, respectively, of the variation. After adjusting for potential confounders, inhalable EC and total inhalable CNT/F structures were associated with the most sputum and blood biomarkers, respectively. Biomarkers associated with at least three CNT/F metrics were 72 kDa type IV collagenase/matrix metalloproteinase-2 (MMP-2), interleukin-18, glutathione peroxidase (GPx), myeloperoxidase, and superoxide dismutase (SOD) in sputum and MMP-2, matrix metalloproteinase-9, metalloproteinase inhibitor 1/tissue inhibitor of metalloproteinases 1, 8-hydroxy-2'-deoxyguanosine, GPx, SOD, endothelin-1, fibrinogen, intercellular adhesion molecule 1, vascular cell adhesion protein 1, and von Willebrand factor in blood, although directions of associations were not always as expected.

CONCLUSIONS

Inhalable rather than respirable CNT/F was more consistently associated with fibrosis, inflammation, oxidative stress, and cardiovascular biomarkers.

Novel Anodic Catalyst Support for Direct Methanol Fuel Cell: Characterizations and Single-Cell Performances

This study introduces a novel titanium dioxide carbon nanofiber (TiO2-CNF) support for anodic catalyst in direct methanol fuel cell. The catalytic synthesis process involves several methods, namely the sol-gel, electrospinning, and deposition methods. The synthesized electrocatalyst is compared with other three electrocatalysts with different types of support. All of these electrocatalysts differ based on a number of physical and electrochemical characteristics. Experimental results show that the TiO2-CNF support gave the highest current density at 345.64 mA mgcatalyst-1, which is equivalent to 5.54-fold that of carbon support while the power density is almost double that of the commercial electrocatalyst.