Surface Of Carbon Nanoparticles Research Articles

Exogenous application of carbon nanoparticles alleviates drought stress by regulating water status, chlorophyll fluorescence, osmoprotectants, and antioxidant enzyme activity in Capsicum annumn L.

Drought is one of the most important abiotic stresses that has a huge negative effect on crop yield. Carbon nanoparticles (CNPs) have received greater attention for their impact on the plants under abiotic stress conditions. However, it is urgently required to apply CNPs to the chili pepper (Capsicum annuum L. cv. Kaskada), which has not yet been studied. The goal of this study was to find out how CNPs affect the growth of chili pepper plants, chlorophyll pigments, proline content, and the activity of antioxidant enzymes when the plants are stressed by drought. Therefore, we synthesized and functionalized CNPs of oil fly ash by one-pot ball milling fabrication. X-ray photoelectron spectroscopy (XPS) was used to identify oxidative moieties on the CNPs surface after exposure to nitric and acetic acids. In the present study, functionalized CNPs were sprayed onto the leaves of 20-day-old plants at various concentrations (6 and 12mg L-1) to determine their effects. We demonstrate that drought stress considerably reduces the plant height, fresh weight (FW), and dry weight (DW). Nevertheless, the exogenous application of functionalized CNPs caused an increase in relative water content (RWC), chlorophyll stability index (CSI), and chlorophyll fluorescence (Fv/Fm) under drought stress. Exogenous functionalized CNPs dramatically increased proline content under drought by reducing abscisic acid (ABA) content in the leaves. When subjected to drought stress, functionalized CNPs boosted antioxidant activities such as superoxide dismutase (SOD) and catalase (CAT) activity. Overall, the positive effects of CNPs on chili pepper seedlings open up new possibilities for developing innovative agricultural techniques, especially when plants are grown in drought conditions.

Stabilization of Carbon Nanotubes and Graphene by Tween-80: Mechanistic Insights from Spectroscopic and Simulation Studies.

Polyoxyethylene sorbitan monooleate is commonly used to obtain stable dispersions of nanoparticles (NPs) such as carbon nanotubes (CNTs) and graphene. However, the mechanism underlying dispersion is poorly understood. The present study aimed at investigating the mechanism of stabilization of carbon NPs (CNPs), namely, single-walled CNTs (SWCNTs), multi-walled CNTs (MWCNTs), and graphene, by Tween-80 using attenuated total internal reflection-Fourier transform infrared and nuclear magnetic resonance (NMR) spectroscopy. Molecular dynamics (MD) simulations were performed to identify, at the atomic scale, the significant interactions that underlie the adsorption and the stabilizing effect of Tween-80 on CNPs, in this way corroborating the spectroscopy results. Spectroscopic analysis revealed that the alkyl chain tether to SWCNT, MWCNT, and graphene surface, presumably through π-π interactions between the carbon-carbon double bond in the alkyl chain and the aromatic rings of CNPs. The hydrophilic polyethoxylate chains extend into the aqueous environment and stabilize the suspension by steric hindrance. MD simulations also showed that Tween-80 molecules interact with the CNP surface via the alkyl chain, thus corroborating spectroscopy results. MD simulations additionally revealed that Tween-80 aggregates on the CNP surface shifted from planar to micelle-like with increasing Tween-80 ratios, underscoring concentration-dependent changes in the nature of these interactions.

Squaramide-Immobilized Carbon Nanoparticles for Rapid and High-Efficiency Elimination of Anthropogenic Mercury Ions from Aquatic Systems

Water pollution due to environmental remediation and poor waste administration in certain areas of the globe signifies a serious problem in acquiring safe and clean drinking water. This problem is especially critical in rural areas, where advanced water purification techniques are deficient, and it remains a daunting task for ecosystem and public health protection. This critical task can be addressed herein by developing scalable poly squaramide-phenyl methacrylamide (PSQ)-functionalized carbon nanoparticles (CNPs) (PSQ-CNPs) with densely populated chelating sites with strong Hg2+-binding capacity. The PSQ-CNPs have shown high efficiency in removing Hg2+ from aqueous solution, providing a Hg2+ capacity of 2840 mg g-1, surpassing all the amine and thiol-based adsorbents reported hitherto. More significantly, the adsorbent reveals the largest distribution coefficient value (Kd) of 9.09 × 1010 mL g-1, which allows it to reduce Hg2+ content from 10 ppm to less than 0.011 ppb, well below the United States Environmental Protection Agency (EPA) limits for drinking water standards (2 ppb). The adsorption measurements of the adsorbent followed the Langmuir isotherm model and pseudo-second order. The practical applicability of PSQ-CNPs was verified with the real samples (the lake, river, and industrial wastewater) and has been proven to be excellent. The adsorbent could still retain its Hg2+ removal efficacy even after 12 sorption cycles. It is attributed that the remarkable performance of PSQ-CNPs arises from the high-density chelating sites and pores on the surface of CNPs. The present work shows a new benchmark for Hg2+-removal adsorbents and presents a novel practical approach for decontaminating Hg2+ and other heavy metal ions from wastewater.

(Digital Presentation) Carbon Quantum Dot Assisted Enhancement of S2 Fluorescence of Near-Infrared Dyes through Immobilization-Induced Emission Effect

Aggregation-induced emission of organic dyes is a phenomenon in which organic luminophores show higher photoluminescence (PL) efficiency in the aggregated state than in a free molecule, due to the freezing rotational degrees of freedom of the luminophore which otherwise quench the PL emission. In many cases, however, coupling of molecules leads to quenching of their emission due to the concentration quenching or self-quenching (exciton-exciton annihilation) effect. Therefore, in order to realize an enhanced PL emission as a result of molecule-molecule interaction a fine balance should be achieved between freezing rotational degrees of freedom of the molecule and escaping self-quenching effect. This could be realized via immobilization of the luminophore onto the inert surface.Here, we demonstrate an enhancement of specific S2 emission of the near-infrared (NIR) dyes of tricarbocyanine family due to their immobilization on the surface of carbon nanoparticles that induce freezing a specific planar conformation of the molecule imposed by the carbon plane of the particle it interact with. Carbon quantum dots serve as inert particles that render an opposite influence on the S1 and S2 emission of the tricarbocyanine dyes. We demonstrate a dual emission of the NIR tricarbocyanine dyes with a bright green S2 fluorescence, which is relatively weak for the free dye molecule but whose quantum yield increases by 2-4 times, together with a strong enhancement of the spontaneous rate of S2 fluorescence, whereas the quantum yield of S1 emission in the NIR decreases by 2-7 times, respectively, as a result of immobilization of the dye molecule via the interaction with carbon quantum dots. The above changes are dependent on the terminal and meso-groups of the dye and the solvent used. The dye immobilization due to interaction with carbon quantum dots causes freezing rotational degrees of freedom of the molecule as indicated by suppression of the dye hot band absorption-assisted anti-Stokes S1 emission.The observed “lighting up” of an anti-Kasha emission, i.e., the emission from Sn (n>1) excited levels, of the NIR chromophores which possess intensive S1 absorption and emission in the NIR region, but which are spectrally silent in the visible, can lead to their potential applications in the fields such as energy conversion, bio-imaging and bio-sensing, sensitization of solar cells, etc.

Molecular Aspects of the Interaction with Gram-Negative and Gram-Positive Bacteria of Hydrothermal Carbon Nanoparticles Associated with Bac8c2,5Leu Antimicrobial Peptide.

Antimicrobial peptides (AMPs) are widely studied as therapeutic agents due to their broad-spectrum efficacy against infections. However, their clinical use is hampered by the low in vivo bioavailability and systemic toxicity. Such limitations might be overcome by using appropriate drug delivery systems. Here, the preparation of a drug delivery system (DDS) by physical conjugation of an arginine-rich peptide and hydrothermal carbon nanoparticles (CNPs) has been explored, and its antimicrobial efficacy against Eschericia coli (E. coli) and Staphylococcus aureus investigated in comparison with the unloaded carrier and the free peptide. The mechanism of interaction between CNPs and the bacteria was investigated by scanning electron microscopy and a combined dielectrophoresis–Raman spectroscopy method for real-time analysis. In view of a possible systemic administration, the effect of proteins on the stability of the DDS was investigated by using albumin as a model protein. The peptide was bounded electrostatically to the CNPs surface, establishing an equilibrium modulated by pH and albumin. The DDS exhibited antimicrobial activity toward the two bacterial strains, albeit lower as compared to the free peptide. The decrease in effectiveness toward E. coli was likely due to the rapid formation of a particle-induced extracellular matrix. The present results are relevant for the future development of hydrothermal CNPs as drug delivery agents of AMPs.

Photoactivatable nanoCRISPR/Cas9 System Based on crRNA Reversibly Immobilized on Carbon Nanoparticles.

Here, we proposed a new approach to engineering a photoactivatable CRISPR/Cas9 gene-editing system. The novel nanoCRISPR/Cas9 system is based on the use of auxiliary photocleavable oligodeoxyribonucleotides (PC-DNAs) complementary to crRNA. PC-DNAs contained up to three UV-sensitive linkers made of 1-(2-nitrophenyl)-1,2-ethanediol inside the oligonucleotide chain. Immobilizing PC-DNAs on the surface of carbon nanoparticles through 3′-terminal pyrene residue provided sufficient blocking of crRNA (and corresponding Cas9 activity) before UV irradiation and allows for crRNA release after UV irradiation at 365 nm, which restores Cas9 activity. We optimized the length of blocking photocleavable oligonucleotide, number of linkers, time of irradiation, and the type of carbon nanoparticles. Based on the results, we consider the nanoCRISPR/Cas9 system involving carbon-encapsulated iron nanoparticles the most promising. It provides the greatest difference of functional activity before/after irradiation and can be used in prospective for magnetic field-controlled delivery of CRISPR system into the target cells or tissues and spatiotemporal gene editing induced by UV irradiation.

Difference in deprotonation for oxygen-containing groups on sp2 and sp3 carbons

Does the hybridization of the surface of carbon nanoparticles (CNPs) affect the properties of the surface carboxyl and hydroxyl groups and the features of their deprotonation in water? To answer these questions in this work the structures of graphite-and diamond-like carbon cells with OH and COOH groups optimized by the DFT method were studied. It was found that in the same suspensions the OH and COOH groups deprotonate easier being on carbon with sp2 hybridization rather than sp3. Theoretical estimates have shown that in aqueous suspensions of CNPs, “isolated” carboxyl COOH groups on sp2/sp3 hybridized carbon sites have pKa in the ranges of 3.5–4.5/4.5–5, and the hydroxyl OH groups – in the ranges of 8.5–10/15–18, respectively. The conclusions made on the basis of theoretical calculations about the features of deprotonation of surface groups of CNPs are experimentally confirmed by the changes of the zeta-potentials of oxidized detonation nanodiamonds with the change of the pH of the environment.

Experimental and DFT studies on the effect of carbon nanoparticles on asphaltene precipitation and aggregation phenomena

• CNPs were synthesized for controlling asphaltene precipitation and aggregation. • FESEM and FTIR demonstrate uniform adsorption of asphaltene on surface of CNPs. • DFT modeling proves the strong hydrogen interaction between CNPs and asphaltenes. • CNPs represent biocompatible and affordable asphaltene inhibitor-dispersant. In this study, a new class of carbon nanoparticles (CNPs) is synthesized for inhibition/dispersion of asphaltene precipitation and aggregation in unstable crude oil. The microscopy and asphaltene dispersant experiments are carried out to assess the effects of CNPs on asphaltene precipitation and aggregation. Also, density functional theory is applied to describe the mechanisms of asphaltene adsorption onto the CNPs surfaces. Experimental results demonstrate postponement of asphaltene onset of precipitation from 26 to 37 vol% n-C 7 in the presence of 400 ppm of the CNPs which is ascribed to the extra high specific surface area of the CNPs. DLS analysis shows the average size of asphaltene aggregates adsorbed onto the CNPs reduces from 1730 nm in the blank oil to 255 nm in treated oil with CNPs. The results of DFT modeling demonstrate the strong hydrogen interaction between functional groups of the CNPs and active sites of asphaltene. Also, π–π interactions occur between electron cloud of aromatic rings of asphaltene and CNPs with minimum equilibrium distance of 2.94 Å. The adsorption energy for the most stable complex of asphaltene and CNPs in the gas and solvent phases are −91.22 and −107.64 kJ/mol, respectively, confirming the strong chemisorption of asphaltene over the CNPs. This research reveals that synthesized CNPs with specific features such as high surface area, potential of covering the external shell with a wide variety of functional groups, low toxicity and cost, and environment-friendly can be successfully implemented as an efficient inhibitor and/or dispersant for asphaltene handling strategies.

Carbon nanoparticle coated by silicon dioxide supported platinum nanoparticles towards oxygen reduction reaction

Herein, a SiO2 thin-layer is coated on the surface of carbon nanoparticles. Such a composite is further utilized as the support to load Pt nanoparticles (Pt/SiO2-C). This Pt/SiO2 -C catalyst features an improved interaction between Pt nanoparticles and the stable SiO2 thin-layer. In acid media, an optimal Pt/SiO2-C catalyst displays significantly improved ORR activity (e.g., a half-wave potential of 0.81 V vs. RHE and a limiting diffusion current of 5.55 mA cm−2) and enhanced ability towards CO andmethanol anti-poisoning. Such performance is superior to the commercial Pt/C catalysts, Pt/carbon nanoparticle based catalysts, and Pt catalysts deposited on other supports. As predicted by density functional theory calculations (DFT), such high ORR performance is mainly due to the reduced free energy barrier, derived from the hydrophilic of SiO2 thin-layer.

Novel Histamine Fluorosensor Based on Modified Environmental Friendly Carbon Nanoparticles From Gum Tragacanth

A novel fluorimetric sensor was synthesized by coating molecularly imprinted polymers (MP) layer on carbon nanoparticles (CNPs) that prepared from gum tragacanth (GT) for determination of histamine dihydrochloride (HDC). Initially, CNPs were prepared in one step by hydrothermal synthesis from a GT aqueous solution. Then, MP coated CNPs (MP-CNPs) were formed by anchoring the MP layer on the surface of CNPs via a sol-gel process. This fluorimetric sensor has the characteristics of both constituents (MP and CNPs) at the same time. It has high selectivity, which is a definite advantage of the MP and also has a high fluorescence intensity due to the presence of CNPs. The novel sensor was used to assay the HDC synthetic and biological samples. The fluorescence intensity of the MP-CNPs decreased linearly by increasing HDC concentration in the range of 0.7- $18.5~\mu $ gL−1, with a detection limit of $0.17~\mu $ g $\text{L}^{-1}$ . The precision of the method for 4.6 and $12.2~\mu $ gL−1 histamine dihydrochloride (HDC) was obtained as 6.8% and 4.3% (n = 3), respectively. The selectivity study showed that this sensor has a high selectivity, which is due to the presence of size-selective cavities and selective interactions on fluorosensor. Furthermore, the suggested method was successfully applied to recognize histamine biological samples with a recovery of 96-103%.

Combating Antibiotic‐Resistant Gram‐Negative Bacteria Strains with Tetracycline‐Conjugated Carbon Nanoparticles

Nontoxic carbon nanoparticle samples prepared by both bottom-up and top-down approaches do not inhibit Gram-negative bacterial growth, indicating excellent biocompatibilities. However, cell growth inhibitory efficacies increase considerably when the carbon nanoparticles are conjugated with the antibiotic tetracycline. In tetracycline-resistant bacteria, these efficacies can approach tenfold higher activities when compared to tetracycline alone. No structural abnormality such as membrane disruptions is evident in the tested bacterial strains; this is in contrast with other nanocarbon systems such as graphene oxides, carbon nanotubes, and amine-functionalized carbon nanoparticles which do exhibit membrane disruptions. In comparison, the tetracycline-conjugated carbon nanoparticles induce membrane perturbations (but not membrane disruptions), inhibiting bacterial efflux mechanisms. It is proposed that when tetracycline is conjugated to the surface of carbon nanoparticles, it functions to direct the nanoparticles to membrane-associated tetracycline efflux pumps, thereby blocking and subsequently inhibiting their function. The conjugation between biocompatible carbon nanoparticles and subtherapeutic but well-established antibiotic molecules may provide hybrid antibiotic assembly strategies resulting in effective multidrug efflux inhibition for combating antibiotic resistance.

Nitrogen-induced shift of photoluminescence from green to blue emission for xylose-derived carbon dots

The discovery of carbon dots opens a new avenue to the applications of nanomaterials in biosensing and bioimaging. In this work, we develop simple methods to prepare carbon nanoparticles from xylose and to tune the photoluminescence (PL) characteristics of the xylose-derived carbon nanoparticles via the combination of three different processes: hydrothermal carbonization (HTC), annealing at 850 °C and laser ablation (LA) in a NH4OH solution. The HTC-synthesized carbon dots (CDs) exhibit green emission under the 365 nm UV excitation, the annealing of the HTC-synthesized CDs leads to complete loss of the PL characteristics, and the LA processing of the annealed carbon nanoparticles recovers the PL characteristics with blue shift in comparison to the HTC-synthesized CDs under the same UV excitation. the PL characteristics of the HTC-CDs and the LA-CDs are dependent on the π-π* transition of C-containing surface-functional groups and π-π* and n-π* transitions of N-containing surface-functional groups, respectively, which are responsible for the difference in the PL characteristics between the HTC-synthesized CDs and the LA-processed CDs. The approaches demonstrated in this work provide a viable method to introduce and tune surface-functional groups on the surface of carbon nanoparticles.

Spectral and Kinetic Studies of Photochromic Systems Based on Graphene and Graphene Oxide Nanostructures

A comparative spectral and kinetic study of the reactions of thiol-substituted molecules of diarylethene and spirooxazine with graphene nanoparticles and graphene oxide nanoplates has been performed. Differences in the photochromic transformations of compounds that are in contact with the surface of carbon nanoparticles in relation to the structure of the compounds and the nature of the nanoparticles are revealed, which indicates the chemical and physical interaction of the molecules of photochromic compounds with the surface groups of carbon nanostructures.

Optically tunable fluorescent carbon nanoparticles and their application in fluorometric sensing of copper ions

A series of carbon nanoparticles (CNPs) with emission wavelength ranging from 483 to 525 nm were prepared by hydrothermal treatment of poly-3-thiopheneacetic acid (PTA) and NaOH. The emission wavelength and surface oxidation degree of CNPs were shown to be controllable by simply adjusting NaOH concentration. These CNPs presented obvious fluorescence spectral response toward copper ions (Cu2+) through static quenching caused synergistically by electron transfer and inner filter effect. The O- and S-containing groups on the surface of CNPs were demonstrated to be responsible for their outstanding sensing performance. Based on that, a CNPs-based ratiometric fluorescent probe for Cu2+ with a high fluorescence quenching rate constant of 1.4 × 105 L/mol and a short response time (10 s) was developed. Their practical applications in detecting Cu2+ in pond water and living cells were also demonstrated.

Spectroscopic approach for the interaction of carbon nanoparticles with cytochrome c and BY-2 cells: Protein structure and mitochondrial function

In this study, we employed multiple spectroscopic methods to analyze the effects of carbon nanoparticles (CNPs) on structure of cytochrome c (Cyt c) and mitochondrial function in plant cells. The tertiary structures of aromatic amino acid in Cyt c were not changed after addition of CNPs. Cyt c was found to be absorbed on the surfaces of CNPs in a non-linear manner and only bound Cyt c can be reduced. In addition, the binding of Cyt c was found to increase the diameter of CNPs at lower concentrations. The redox potential of Cyt c was almost not affected after treatment with CNPs. There were no obvious differences in cellular ATP after exposure to CNPs, and the mitochondrial membrane potential (MMP) was significantly decreased once the CNPs concentration exceeded 31.25 μg/mL. The levels of reactive oxygen species (ROS) also were increased in BY-2 cells. Taken together, these findings provide basis for the interactions between CNPs and Cyt c, as well as the effect of CNPs treatment on the mitochondria function in plant cells.

Surface treatment of carbon nanoparticles by nitrogen/oxygen alternating current arc discharge and the application in ABS/EPDM composites

Abstract The combination of an alternating current arc reactor and a fluidized bed has been developed to offer a new route for the surface modification of carbon nanoparticles. In this method, O- and N-doped carbon nanoparticles were successfully obtained after treatment under different plasma atmospheres. The treated and untreated particles were then melt-blended with acrylonitrile-butadiene-styrene/ethylene-propylene-diene monomer composites to reinforce the mechanical and electrical properties. The results showed that, after surface modification, polar functional groups were successfully introduced onto the surface of carbon nanoparticles but the crystalline structure had been changed. Tensile strength and impact strength of ABS/EPDM filled with treated particles have been remarkably improved since the incompatible carbon nanoparticles could be imbedded into the matrix compatibly after modification while electrical resistivity showed complex variation tendency.

Carbon Nanoparticles Based Electrochemical Biosensor Strip for Detection of Japanese Encephalitis Virus

We reported a disposable and sensitive electrochemical biosensor strip based on carbon nanoparticles modified screen-printed carbon electrode (SPCE) for rapid and sensitive detection of Japanese Encephalitis Virus (JEV). Amino group functionalized carbon nanoparticles were prepared from preformed chitosan nanoparticles. Japanese Encephalitis Virus (JEV) antibody was immobilized onto the surfaces of carbon nanoparticles through amide bonds formation between amino groups of carbon nanoparticles and carboxylic groups of JEV antibody. The analytical performance of SPCE electrochemical biosensor strip was characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). SPCE electrochemical biosensor strip exhibited a linear detection range of 1–20 ngmL−1 with a low detection limit of 0.36 ngmL−1 (at S/N = 3) for JEV, detection sensitivity was 0.024 ngmL−1 for JEV, and analysis results were obtainable within 10 minutes. The potential clinical application of this SPCE electrochemical biosensor strip was demonstrated by the detection of JEV in human serum.

Surface Modification of Carbon Nanofibers and Graphene Platelets Mixtures by Plasma Polymerization of Propylene

Carbon nanofibers (CNFs), graphene platelets (GPs), and their mixtures were treated by plasma polymerization of propylene. The carbon nanoparticles (CNPs) were previously sonicated in order to deagglomerate and increase the surface area. Untreated and plasma treated CNPs were analyzed by dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and thermogravimetric analysis (TGA). DLS analysis showed a significant reduction of average particle size, due to the sonication pretreatment. Plasma polymerized propylene was deposited on the CNPs surface; the total amount of polymerized propylene was from 4.68 to 6.58 wt-%. Raman spectroscopy indicates an increase in the sp3 hybridization of the treated samples, which suggest that the polymerized propylene is grafted onto the CNPs.

Thermal Evaporation of Sb2Se3 as Novel Counter Electrode for Dye‐Sensitized Solar Cells

AbstractSb2Se3 was fabricated with a facile atmospheric pressure thermal evaporation procedure as counter electrode (CE) for dye‐sensitized solar cells (DSSCs). The introduction of a carbon nanoparticle (CNP) film as substrate was proved to facilitate Sb2Se3 deposition, resulting in the formation of a Sb2Se3 layer on the surface of carbon nanoparticles (denoted as CNP‐Sb2Se3). Electrochemical characterizations demonstrate the intrinsic catalytic ability of Sb2Se3 and better electrocatalytic activity and stability of Sb2Se3 deposited on CNP film in catalyzing I3‐ reduction. Evaporation temperature was found to affect the electrocatalytic activity of CNP‐Sb2Se3 and a lower temperature of 400oC was proved to be better in our case. As a result, the best performing DSSC with CNP‐Sb2Se3 CE yields a power conversion efficiency of 6.26%, which is comparable to that based on Pt CE (6.47%).

Fluorometric immunoassay for detecting the plant virus Citrus tristeza using carbon nanoparticles acting as quenchers and antibodies labeled with CdTe quantum dots

Cadmium-telluride quantum dots (QDs) were conjugated to an antibody (Ab) against Citrus tristeza virus (CTV), while the coat protein (CP) of the CTV was immobilized on the surface of carbon nanoparticles (CNPs). Following immunobinding of the QD-Ab and the CP-loaded CNPs, the fluorescence of the CdTe QDs was quenched by the CNPs. This effect was exploited to design a detection assay for the CTV which was found more sensitive and specific than the existing enzyme linked immunosorbent assay (ELISA). The limit of detection was measured at about 220 ng⋅ mL‾1 of CTV. The Stern-Volmer plot of the CNPs-QD quencher pair showed a positive deviation from linearity which was ascribed to the presence of both static and dynamic quenching.