Magneto-optical binding in the near field

In this paper we show analytically and numerically the formation of a near-field stable optical binding between two identical plasmonic particles, induced by an incident plane wave. The equilibrium binding distance is controlled by the angle between the polarization plane of the incoming field and the dimer axis, for which we have calculated an explicit formula. We have found that the condition to achieve stable binding depends on the particle’s dielectric function and happens near the frequency of the dipole plasmonic resonance. The binding stiffness of this stable attaching interaction is four orders of magnitude larger than the usual far-field optical binding and is formed orthogonal to the propagation direction of the incident beam (transverse binding). The binding distance can be further manipulated considering the magneto-optical effect and an equation relating the desired equilibrium distance with the required external magnetic field is obtained. Finally, the effect induced by the proposed binding method is tested using molecular dynamics simulations. Our study paves the way to achieve complete control of near-field binding forces between plasmonic nanoparticles.

Investigation of Formaldehyde Adsorption on Carbon Nanotubes by Density Functional Theory

Background: Formaldehyde (HCOH) is the most abundant airborne carbonyl indoor volatile organic compound (VOC), which is well-known to cause serious health effects such as respiratory system disease, immune system disorders, and central nervous system damage. Methods: The interaction between HCOH and intrinsic, congeners of Au, Ag, Cu-doped SWCNTs were investigated by density functional theory (DFT) to evaluate the detection of formaldehyde. Results: The results demonstrated that the less adsorption on the surface of intrinsic SWCNT, an HCOH molecule tended to be chemisorbed to the Au, Ag, and Cu atoms of doped SWCNT with larger binding energy of 0.4-0.8 eV and smaller binding distance of 1.9-2.3 Å. Furthermore, charge transfer and density of state studies indicated tha t the electronic properties changed evidently in the most stable HCOH-doped SWCNT systems, mainly at the region of -5.5 to -4.5 eV and Fermi level. Conclusion: More importantly, the adsorption of HCOH affected the electronic conductance of doped SWCNT. It is expected that the results obtained in this study could provide a useful theoretical guidance for the investigation of molecular films interface bonding and design of HCOH sensing devices.

Investigation on the Interaction between Tetrakis (4-carboxylphenyl) Porphyrin and CopC by Spectroscopy and Docking Methods

Background: Recently, the small molecule that inhibits the human copper-trafficking proteins Atox1 and CCS was reported, which suggested that small molecule has an effect on the copper regulation system in the cell. The copper chaperones CopC is regarded as a redox switch and possess barrel structure, thus the interaction between CopC and small molecules could give helpful information to elucidate the copper regulation mechanism. In addition, porphyrins play an important role in the metabolism of living body. In the early-stage tumors, porphyrins were usually used to diagnosis. After the amphiphilic porphyrins were given by intravenous injection, serum albumins and serum proteins were the most usual carrier to transfer them. Then these molecules can accumulate in malignant tumours and contact with cancer cells. Obviously, in drug distribution and efficacy, investigation of the interaction between the porphyrins and protein is an important research area. Obviously, in drug distribution and efficacy, investigation of the interaction between the porphyrins and protein is an important research area. Objective: In this article, our motivation is to establish a relation between Tetrakis (4- carboxylphenyl) porphyrin and CopC. Methods: In this article, we propose a framework for achieving our aforementioned object. Firstly, FTIR spectra and CD were used to detect the structure changes of CopC. Secondly, the fluorescence spectroscopic and UV-Vis spectra were used to measure quenching mechanism, binding distance, binding site and binding distance. Using Tb 3+ as a probe to detect the interaction between CopC and TCPP. Finally, molecular docking methods was used to show the results more vivid. Result: Following the proposed framework, firstly, FTIR and CD results indicated that the CopC conformation was changed by TCPP. The β-sheet content was reduced and the random coil content was increased. Secondly, fluorescence spectra data indicated that the combination ratio of TCPPCopC was 1:1, and the inclusion constant is (5.88 ± 0.12) × 10 5 M -1 . In addition, Tb 3+ was used as a probe to detect the interaction between CopC and TCPP. The result further verified that CopC can interact with TCPP. The thermodynamic parameters of interaction between CopC and TCPP (ΔH, ΔS) indicated that the force between CopC and TCPP was mainly hydrophobic interaction. Finally, the distance between tryptophan in CopC and TCPP was calculated through forster energy transfer and molecular docking. Conclusion: The results revealed that TCPP can form 1:1 complex with CopC, and the binding constant has been calculated to be (5.88 ± 0.12) × 10 5 M -1 . In addition, it was revealed that TCPP quench the fluorescence of CopC by the static quenching mechanism and the binding site n equals one. The formation of CopC-TCPP complex depended on the hydrophobic force and the distance between TCPP and tryptophan residue in CopC was 2.07 nm.

All-optical switching and real-time spectroscopy of soliton molecules in a few-cycle laser oscillator

Bound states of femtosecond solitons are generated and controlled in a commercial sub-10 fs Kerr-lens mode-locked ultrashort oscillator. Using real-time time-stretch interferometry, we resolve the resonance of vibrating soliton molecules and demonstrate all-optical switching between stable bound-states of different binding distance.

Assessment of Binding Interaction between Bovine Lactoferrin and Tetracycline Hydrochloride: Multi-Spectroscopic Analyses and Molecular Modeling

In this paper, the interaction between bovine lactoferrin (bLf) and tetracycline hydrochloride (TCH) was researched by microscale thermophoresis (MST), multi-spectroscopic methods, and molecular docking techniques. Normal fluorescence results showed that TCH effectively quenched the intrinsic fluorescence of bLf via static quenching. Moreover, MST confirmed that the combination force between bLf and TCH was very strong. Thermodynamic parameters and molecular docking further revealed that electrostatic forces, van der Waals, and hydrogen bonding forces played vital roles in the interaction between bLf and TCH. The binding distance and energy transfer efficiency between TCH and bLf were 2.81 nm and 0.053, respectively. Moreover, the results of circular dichroism spectra (CD), ultraviolet visible (UV-vis) absorption spectra, fluorescence Excitation-Emission Matrix (EEM) spectra, and molecular docking verified bLf indeed combined with TCH, and caused the changes of conformation of bLf. The influence of TCH on the functional changes of the protein was studied through the analysis of the change of the bLf surface hydrophobicity and research of the binding forces between bLf and iron ion. These results indicated that change in the structure and function of bLf were due to the interaction between bLf and TCH.

Graphene on Cu(111) at the nonzero temperatures: Molecular dynamic simulation

We present results of molecular dynamic simulation of continuous graphene monolayer on Cu(111). In this paper, we investigate the dependencies of the average binding energy and the average binding distance on the temperature. The interaction between carbon and copper atoms was described by Lennard-Jones potential. It is shown that the binding energy practically remains constant in a wide range of temperatures 0–800 K. However, in the same temperature range, the binding distance of graphene on Cu(111) surface has a linear dependence on temperature. The dependence of the linear thermal expansion coefficient of the binding distance on Lennard-Jones parameters has been calculated. We suggest a simple theoretical model to explain this dependence qualitatively.

Formaldehyde adsorption on carbon nanotubes fragment by density functional theory

The interaction between formaldehyde (HCOH) and pristine single-walled carbon nanotube (SWCNT) fragment was investigated by density functional theory (DFT) to evaluate the detection of HCOH. The simulation results demonstrated less adsorption on surface of SWCNT and doped CNTs, while a HCOH molecule tended to be chemisorbed to the C atom located on SWCNT’s edge positions with larger binding energy of 1.742 eV and smaller binding distance of 1.351 Å. Furthermore, charge transfer and density of states study indicated that the electronic properties changed evidently in the most stable HCOH-SWCNT system, and were mainly around the Fermi level. More importantly, the adsorption of HCOH affected the electronic conductance of SWCNT. It is expected that the results could provide a useful theoretical guidance for the investigation of molecular films interface bonding and design of HCOH sensing devices.

Theoretical Study on Structural and Electronic Properties of EDOT:SS Oligomers Complex

In this paper, we have reported a theoretical study of the geometric and electronic structures of EDOT:SS oligomers based on semi-empirical Austin model1 (AM1) method and density functional theory at B3LYP/3-21G* level. The effects of polymer chain length of both EDOT and SS on structural and electronic properties including bond length, bond angle, binding distance, charge, the highest occupied orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and energy gap have been studied from the optimized oligomers which were built by varying repeating unit of monomer as n = 1, 2, 3 and 4. The results show that AM1 is not appropriate for geometry optimization of EDOT:SS system comparing to B3LYP/3-21G* level. The binding distance between H atom on EDOT and O atom on SS tends to close together with the average distance of 2.21 Å. The most positive charges locate at sulfur atoms on EDOT and EDOT:SS. The electrical conductivity of EDOT, SS and EDOT:SS increases when polymer chain is extended.