Characterizing the sensitivity of bonds to the curvature of carbon nanotubes

Computational simulation on the study of Tacrolimus and its improved dermal retention using Poly(Ԑ-caprolactone) nanocapsules

Tacrolimus (TAC) is a drug from natural origin that can be used for topical application to control autoimmune skin diseases such as atopic dermatitis, psoriasis, and vitiligo. Computational simulation based on quantum mechanics theory by solving Schrödinger Equation for n-body problem may allow the theoretical calculation of drug geometry, charge distribution and dipole moment, electronic levels and molecular orbitals, electronic transitions, and vibrational transitions. Additionally, the development of novel nanotechnology-based delivery systems containing TAC can be an approach for reducing the dose applied topically, increasing dermal retention, and reducing the reported side effects due to the controlled release pattern. Firstly, this paper was devoted to obtaining the molecular, electronic, and vibrational data for TAC by using five semi-empirical (SE) methods and one Density Functional Theory (DFT) method in order to expand the knowledge about the drug properties by computational simulation. Then, this study was carried out to prepare TAC-loaded poly(ԑ-caprolactone) nanocapsules by interfacial polymer deposition following solvent displacement and investigate the in vitro drug permeation using the Franz diffusion cell and the photoacoustic spectroscopy. Computational simulations were compared in the three schemes SE/SE, SE/DFT, and DFT/DFT, where the first method represented the procedure used for geometry optimization and the second one was performed to extract electronic and vibrational properties. Computational data showed correspondence with TAC geometry description and electronic properties, with few differences in HOMO - LUMO gap (Δ) and dipole values. The SE/DFT and DFT/DFT methods presented a better drug description for the UV-Vis, Infrared, and Raman spectra with low deviation from experimental values. Franz cell model demonstrated that TAC was more delivered across the Strat-M® membrane from the solution than the drug-loaded poly(ԑ-caprolactone) nanocapsules. Photoacoustic spectroscopy assay revealed that these nanocapsules remained more retained into the Strat-M® membranes, which is desirable for the topical application.

Effect of Multi-walled Carbon Nanotubes Functionalized with Kinetin on the Development of Avena sativa

In pioneering research, it has been documented that the CNT influences the development of plants through the balance of phytoregulators. Therefore, in this work the objective is to evaluate the effects of the CNT functionalized by non-covalent method with kinetin that have in Avena sativa. CNT was characterized by FTIR and Raman to confirm functionality. The results showed that the application of CNT with phytoregulators modified plant development.

Effect of Multi-walled Carbon Nanotubes Functionalized with Indol-3-butyric Acid on the Development of Avena sativa

In pioneering research, it has been documented that the CNT influences the development of plants through the balance of phytoregulators. Therefore, in this work the objective is to evaluate the effects of CNT functionalized by non-covalent method with indole-3-butyric acid that they have on Avena sativa. The CNT was characterized by FTIR and Raman to confirm functionalization. It was observed that in the germination stage the seeds treated with IBA inhibited germination, however, when functionalizing the CNT with IBA it was observed that the CNT is contributing to counteract this inhibition.

Investigation of optical properties for N- and F-doped triangular shaped carbon molecules

Optical properties of N- and F-doping triangular-shaped carbon molecules have been investigated in theory and experiment. The theoretical results showed that carbon molecules with impurity F and Cl have the same characters with pure carbon. Doping N into pure carbon molecule would change the optical rotation at 589 nm. For doping N replacing hydrogen atom structures (N-doping 1 and N-doping 2 molecules), the absorption spectra of them are similar to pure carbon molecule. However, for molecules with impurity N atom in benzene ring (N-doping 3 and N-doping 4 molecules), the peaks of wavelength of absorption spectra shift to long wavelength compared to that of pure carbon molecule. Moreover, the delocalization of molecular orbital (MO) is different from pure carbon molecule, which is caused by the impurity N changing the electrons distribution of benzene ring. We have calculated 3 without H and 4 without H molecules which are removing hydrogen atom in nitrogen atom from N-doping 3 and 4. 3 without H and 4 without H molecules have similar optical properties with pure carbon molecule. The results testified that the impurity N and F would not change the optical properties of carbon molecule if impurity did not change the delocalization of all benzene rings. Optical properties of nitrogen- and fluorine-doping carbon molecules investigating in theory and experiment.

Carbon Nanomaterials: Synthesis, Functionalization and Sensing Applications

Recent advances in nanomaterial design and synthesis has resulted in robust sensing systems that display superior analytical performance. The use of nanomaterials within sensors has accelerated new routes and opportunities for the detection of analytes or target molecules. Among others, carbon-based sensors have reported biocompatibility, better sensitivity, better selectivity and lower limits of detection to reveal a wide range of organic and inorganic molecules. Carbon nanomaterials are among the most extensively studied materials because of their unique properties spanning from the high specific surface area, high carrier mobility, high electrical conductivity, flexibility, and optical transparency fostering their use in sensing applications. In this paper, a comprehensive review has been made to cover recent developments in the field of carbon-based nanomaterials for sensing applications. The review describes nanomaterials like fullerenes, carbon onions, carbon quantum dots, nanodiamonds, carbon nanotubes, and graphene. Synthesis of these nanostructures has been discussed along with their functionalization methods. The recent application of all these nanomaterials in sensing applications has been highlighted for the principal applicative field and the future prospects and possibilities have been outlined.

Confinement Effects of a Noble Gas Dimer Inside a Fullerene Cage: Can It Be Used as an Acceptor in a DSSC?

A detailed density functional theory investigation of He₂-encapsulated fullerene C₃₆ and C₄₀ has been presented here. When confinement takes place, He-He bond length shortens and a non-covalent type of interaction exists between two He atoms. Energy decomposition analysis shows that though an attractive interaction exists in free He₂, when it is confined inside the fullerenes, repulsive interaction is observed due to the presence of dominant repulsive energy term. Fullerene C₄₀, with greater size, makes the incorporation of He₂ much easier than C₃₆ as confirmed from the study of boundary crossing barrier. In addition, we have studied the possibility of using He₂-incorporated fullerene as acceptor material in dye-sensitized solar cell (DSSC). Based on the highest energy gap, He₂@C₄₀ and bare C₄₀ fullerenes are chosen for this purpose. Dye constructed with He₂@C₄₀ as an acceptor has the highest light-harvesting efficiency and correspondingly will possess the maximum short circuit current as compared to pure C₄₀ acceptor.

Theoretical prediction of the impact sensitivities of energetic C-nitro compounds

In order to design high-energetic and insensitive explosives, the frontier orbital energy gaps, surface electrostatic potentials, nitro group charges, bond dissociation energies (BDEs) of the C-NO₂ trigger bonds, and intermolecular interactions obtained by the M06-2X/6-311++G(2d,p) method were quantitatively correlated with the experimental drop hammer potential energies of 10 typical C-nitro explosives. The changes of several information-theoretic quantities (ITQs) in the density functional reactivity theory were discussed upon the formation of complexes. The BDEs in the explosives with six-membered ring are larger than those with five-membered ring. The frontier orbital energy gaps of the compounds with benzene ring are larger than those with N-heterocycle. The models involving the intermolecular interaction energies and the energy gaps could be used to predict the impact sensitivity of the C-nitro explosives, while those involving ΔS_S, ΔI_F, and ΔS_GBP are invalid. With the more and more ITQs, the further studies are needed to seek for a good correlation between impact sensitivity measurements and ITQs for the energetic C-nitro compounds. The origin of sensitivity was revealed by the reduced density gradient method.

Non-covalent interactions between epinephrine and nitroaromatic compounds: A DFT study

Here, we present a density functional theory (DFT) study of hydrogen bonding and π-π stacking interactions between epinephrine and different aromatic nitro-compounds in gas phase as well as in methanol solvent. Detail investigations of hydrogen bonding and π-π interactions are performed and confirmed on the basis of theoretical IR spectra, natural bond orbital (NBO) analysis, non-covalent interaction (NCI), chemical reactivity descriptors and electronic spectra. Among different functionals used for the calculation, the results obtained from ωB97XD functional are found to be more suitable to describe the hydrogen bonding and π-π stacking phenomenon for our considered systems. Weakening of hydrogen bonding and π-π stacking interaction on solvent incorporation is observed. Electronic transition between different orbitals and transition probabilities of epinephrine and nitro-aromatic complexes are described using time dependent density functional theory (TD-DFT) method.