Palladium Metal Nanocomposites Based on PEI-Functionalized Nitrogen-Doped Graphene Quantum Dots: Synthesis, Characterization, Density Functional Theory Modeling, and Cell Cycle Arrest Effects on Human Ovarian Cancer Cells.

In this study, the synthesis, characterization, density functional theory calculations (DFT), and effect of polyethylenimine (PEI)-functionalized nitrogen-doped graphene quantum dots (PEI N-GQDs) and their palladium metal nanoparticles nanocomposites (PdNPs/PEI N-GQDs) on cancer cells were extensively investigated. The focus also includes investigating their cytotoxic and apoptotic effects on ovarian cancer cells, which pose a serious risk to women's health and have high death rates from delayed diagnosis, inadequate response to treatment, and decreased survival. Graphene quantum dots and their palladium nanocomposites were differentially effective against ovarian cancer cell lines. In particular, the smaller particle size and morphology of PdNPs/PEI N-GQDs nanocomposites compared with PEI N-GQDs probably enhance their activity through highly improved uptake by cells. These findings emphasize the importance of particle size in composite drugs for efficient cancer treatment. DFT results revealed that the Pd-containing nanocomposite, with a smaller highest occupied molecular orbital-lowest unoccupied molecular orbital gap, exhibited higher reactivity and anticancer effects in human ovarian cancer cell line, OVCAR-3. Significantly, the application of nanocomposites to ovarian cancer cells initiated apoptosis, offering valuable insights into the intricate interplay between nanomaterials and cancer biology.

Two-Photon Absorption Response of Functionalized BODIPY Dyes in Near-IR Region by Tuning Conjugation Length and Meso-Substituents.

BODIPY dyes substituted by phenol or -COOMe units at the meso-position (C8) with and without a distyryl group including a methoxy moiety at the -C3 and -C5 positions of the BODIPY have been synthesized to analyze the photophysical properties. To clarify the ground-state interaction, absorption and emission features were investigated in the THF environment. Extending the π-conjugation with the methoxy moiety at -C3 and -C5 positions of BODIPY leads to a spectral shifting of the absorption maxima toward red by 120 nm. In addition, attaching the -COOMe unit at the meso-position of the BODIPY structure increases nonradiative molecular relaxation as compared to compounds possessing phenol substituents at the same position. We have investigated the effect of phenol and a -COOMe group and π-extended conjugation length with a methoxy moiety on the properties of two-photon absorption (TPA) and electron transfer dynamics by performing open-aperture (OA) Z-scan and femtosecond transient absorption spectroscopy measurements, respectively. The synthesized BODIPY compounds with the distyryl group including the methoxy unit show TPA character due to the longer conjugation length and therefore intramolecular charge transfer ability. Based on the OA Z-scan experiments upon photoexcitation with 800 nm pulsed laser light, TPA cross-section values were obtained as 74 and 81 GM for the compounds possessing phenol and -COOMe units at the meso-position of BODIPY treated by distyryl group with methoxy moieties, respectively. Additionally, optical and electronic properties were calculated theoretically by using the DFT method.

Effects of Heavy Iodine Atoms and π-Expanded Conjugation on Charge Transfer Dynamics in Carboxylic Acid BODIPY Derivatives as Triplet Photosensitizers.

Borondipyrromethene (BODIPY) chromophores are composed of a functional-COOH group at meso position with or without a biphenyl ring, and their compounds with heavy iodine atoms at -2, -6 positions of the BODIPY indacene core were synthesized. The photophysical properties of the compounds were studied with steady-state absorption and fluorescence measurements. It was observed that the absorption band is significantly red-shifted, and fluorescence signals are quenched in the presence of iodine atoms. In addition to that, it was indicated that the biphenyl ring does not affect the spectral shifting in the absorption as well as fluorescence spectra. In an attempt to investigate the effect of π-expanded biphenyl moieties and heavy iodine atoms on charge transfer dynamics, femtosecond transient absorption spectroscopy measurements were carried out in the environment of the tetrahydrofuran (THF) solution. Based on the performed ultrafast pump-probe spectroscopy, BODIPY compounds with iodine atoms lead to intersystem crossing (ISC) and ISC rates were determined as 150 ps and 180 ps for iodine BODIPY compounds with and without π-expanded biphenyl moieties, respectively. According to the theoretical results, the charge transfer in the investigated compounds mostly appears to be intrinsic local excitations, corresponding to high photoluminescence efficiency. These experimental findings are useful for the design and study of the fundamental photochemistry of organic triplet photosensitizers.

Two-photon absorption and triplet excited state quenching of near-IR region aza-BODIPY photosensitizers via a triphenylamine moiety despite heavy bromine atoms.

Aza-BODIPY compounds with methoxy groups at -3 and -5 and triphenylamine moieties at -1 and -7 positions with and without heavy bromine atoms at -2 and -6 positions have been designed and synthesized. The chemical structures of the novel compounds were fully characterized using 1H NMR, 13C NMR, FTIR, and HRMS-TOF-ESI techniques. Steady-state absorption and emission features were investigated to analyze ground-state interactions. The effects of triphenylamine moieties and bromine atoms on charge transfer dynamics and two-photon absorption (TPA) properties were investigated using femtosecond transient absorption spectroscopy measurements and open-aperture (OA) Z-scan experiments, respectively. Contrary to popular belief, the compound containing heavy bromine atoms and triphenylamine moieties did not demonstrate any triplet transition. Since the triphenylamine moiety has high electron-donating properties and a long conjugation length, it exhibited intramolecular charge transfer (ICT) features from electron-donating moieties to the aza-BODIPY core. Additionally, it is concluded that the excited-state lifetime is shortened in the presence of a bromine atom with triphenylamine moieties. This result is rather interesting since the triplet excited state is quenched by the triphenylamine moiety despite the presence of a heavy bromine atom. The performed OA Z-scan experiments revealed that the aza-BODIPY compound containing bromine atoms has a higher TPA cross-section value (116 GM) due to efficient intramolecular charge transfer compared to that without bromine atoms (89 GM). Additionally, in the theoretical calculations, it was found that the charge transfer percentage (CT%) was the strongest in compounds containing bromine atoms.

Effect of confinement potential shape on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot at finite temperature.

The effect of the shape of the confinement potential on the electronic, thermodynamic, magnetic and transport properties of a GaAs quantum dot is studied using the power-exponential potential model with steepness parameter p. The average energy, heat capacity, magnetic susceptibility and persistent current are calculated using the canonical ensemble approach at low temperature. It is shown that for soft confinement, the average energy depends strongly on p while it is almost independent of p for hard confinement. The heat capacity is found to be independent of the shape and depth of the confinement potential at low temperatures and for the magnetic field considered. It is shown that the system undergoes a paramagnetic-diamagnetic transition at a critical value of the magnetic field. It is furthermore shown that for low values of the potential depth, the system is always diamagnetic irrespective of the shape of the potential if the magnetic field exceeds a certain value. For a range of the magnetic field, there exists a window of p values in which a re-entrant behavior into the diamagnetic phase can occur. Finally, it is shown that the persistent current in the present quantum dot is diamagnetic in nature and its magnitude increases with the depth of the dot potential but is independent of p for the parameters considered.

Molecular simulation of PcCel45A protein expressed from Aspergillus nidulans to understand its structure, dynamics, and thermostability.

PACS and mathematical subject classification numbers as needed. Molecular dynamic simulation is a very usable tool to understand various factors, including structure temperature dependence, dynamics, and stability for protein structure. The three main components, namely endoglucanase, exoglucanase, and ß-glucosidase, effectively convert lignocellulosic biomass into fermentable sugar. Cellulose is the major component of plant cell walls and is the most abundant organic compound on the earth. Somewhat organisms can use cellulose as a food source, possessing cellulases (cellobiohydrolases and endoglucanases) that can catalyze the hydrolysis of the ß-(1,4) glycosidic bonds. In this work, we investigated conformational and structural properties of PcCel45A protein by changing at temperatures with 300 K, 333 K, and 352 K. We found that the ASN92 residue was the major contributor to the stability of structure; some other residues correlated significantly with thermal stability. We also compared the theoretical results of the current study with the experimental ones published in previous studies.

Synthesis, characterization, and evaluation of (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate as a biological agent and an anion sensor.

An amino acid based and bidentate Schiff base, (E)-methyl 2-((2-oxonaphthalen-1(2H)-ylidene)methylamino)acetate (ligand), was synthesized from the reaction of glycine-methyl ester hydrochloride with 2-hydroxy-1-naphthaldehyde. Characterization of the ligand was carried out using theoretical quantum-mechanical calculations and experimental spectroscopic methods. The molecular structure of the compound was confirmed using X-ray single-crystal data, NMR, FTIR and UV-Visible spectroscopy, which were in good agreement with the structure predicted by the theoretical calculations using density functional theory (DFT). Antimicrobial activity of the ligand was investigated for its minimum inhibitory concentration (MIC) to several bacteria and yeast cultures. UV-Visible spectroscopy studies also shown that the ligand can bind calf thymus DNA (CT-DNA) electrostatic binding. In addition, DNA cleavage study showed that the ligand cleaved DNA without the need for external agents. Energetically most favorable docked structures were obtained from the rigid molecular docking of the compound with DNA. The compound binds at the active site of the DNA proteins by weak non-covalent interactions. The colorimetric response of the ligand in DMSO to the addition of equivalent amount of anions (F-, Br-, I-, CN-, SCN-, ClO4-, HSO4-, AcO-, H2PO4-, N3- and OH-) was investigated and the ligand was shown to be sensitive to CN- anion.