Bendamustine (BENDA) has both alkylating and purinergic antitumor activities and remains effective in some cancers that have developed drug resistance, and there are few studies on the interaction mechanism of BENDA with DNA. In this paper, the interaction mechanism between BENDA and calf thymus DNA (ctDNA) was systematically investigated at the single molecular level, mainly by using ultraviolet-visible spectroscopy (UV-vis), Confocal Raman spectroscopy, and molecular docking. In UV-vis absorption spectroscopy experiments, the effects of ctDNA solution concentration, temperature, time and Na+ ions on the spectral production were investigated, respectively, and the experimental results showed that the interaction mode between BENDA and ctDNA was external bonding, i.e., groove binding and electrostatic binding. In addition, the disappearance and shift of the corresponding characteristic peaks in the Raman peaks indicate that BENDA interacts mainly with the phosphate backbone and base G of the ctDNA molecule, and causes some shifts in other bases and deoxyribose. Molecular docking simulations show that BENDA binds in the minor groove region of DNA and that the N and O atoms in the BENDA structure form intermolecular hydrogen bonds with base G, respectively. The results of this paper help to understand the mechanism of action of anti-cancer drugs and provide some reference for the development of new drugs with less toxic side effects.
We present stable dispersion-managed soliton (DMS) molecules in a passively mode-locked Yb-doped polarization-maintaining fiber laser based on chirped fiber Bragg grating in the anomalous dispersion regime. The generation of DMSs are characterized by their sech2-like spectral profile with no steep spectral edges, which is distinct from those of dissipative solitons generated in Yb-doped fiber lasers with a large net positive cavity group velocity dispersion regime. The pulse width is 4.8 ps if the sech2 profile is assumed. The corresponding pulses width could be compressed to 278 fs with grating pair compressor. Furthermore, DMS molecules exhibit multiple discrete equilibrium distances and a regular spectral modulation pattern. All these DMS molecules are stable in the sense that after being obtained they can remain several days. The proposed laser proves its great potential to future practical use in high-resolution optics for coding and optical communication.
The current state of single frequency fiber laser technology based on different saturable absorbers (SA) is reviewed. The proposed and experimental fiber lasers used ytterbium-doped fiber (YDF) as the gain medium and the mode selection is done by Sagnac interferometer loop mirror filter (LMF) incorporated SA. In this paper, we review the experiment principle and process of SF fiber lasers utilizing different function materials as the SA, including the fabrication, features of the two-dimensional (2-D) materials (graphene and molybdenum disulfide film) SA. The SA is like a narrowband filter to ensure the longitudinal mode operation. Finally, we systematically analysis and compare the experimental results based on different SA.
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