Comparative inflorescence and floral ontogeny in the genus Mentha (Mentheae: Nepetoideae: Lamiaceae): variable sequences of organ appearance and random petal aestivation

The genus Mentha is a taxonomically complex genus, characterized by large morphological variations. Only a few, frequently overlapping, characters are of value in taxonomy. Comparative floral developmental studies provide an opportunity for better understanding the systematic relationships among different species. The inflorescence and floral ontogeny of three Mentha L. species (M. piperita L., M. pulegium L. and M. suaveolens Ehrh.) were investigated using epi-illumination light microscopy. All three species studied have thyrses with the same developmental pathway. The lack of higher order bracts and the monochasial branching of the higher order inflorescence apices were found as special features of inflorescence ontogeny. Sepals appear unidirectionally from the adaxial side in all except for M. pulegium which shows a modified unidirectional sequence. Variable sequences of petal and stamen appearance from unidirectional to reversed unidirectional sequence are present in all. Significant ontogenetic features include (1) appearance of the corolla as a rim before petal lobes become visible and (2) instability in petal aestivation. Morphological features including densely hairy calyx, five-lobed corolla tube, smaller adaxial stamens and hairy ovary with included style distinguish M. pulegium from the other species. On the basis of our results floral ontogenetic features could be considered important characters for delimiting or diagnosing different sections in the genus Mentha. Variable sequences of petal lobe appearance and instability in petal aestivation were found as unusual developmental characters.     

Investigation on the interaction of newly designed potential antibacterial Zn(II) complexes with CT-DNA and HSA

Two Zn(II) complexes of formula [Zn(bpy)(Gly)]NO₃ (I) and [Zn(phen)(Gly)]NO₃ (II) (where bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline and Gly = glycine) were synthesized and characterized by elemental analysis, molar conductance measurements, UV–vis, FT-IR, and ¹H NMR spectra. The interaction ability of these complexes with calf thymus DNA was monitored using spectroscopic methods, including UV–vis absorption spectroscopy, ethidium bromide displacement, Fourier transform infrared, and electrophoretic mobility assay. Further, the human serum albumin interactions of complexes I and II were investigated using UV–vis absorption spectroscopy, fluorescence quenching, circular dichroism, and Fourier transform infrared. The results obtained from these analyses indicated that both complexes interact effectively with CT-DNA and HSA. The binding constant (K_b), the Stern–Volmer constant (K_sv), and the number of binding sites (n) at different temperatures were determined for CT-DNA and HSA. Also, the negative ΔH° and ΔS° values showed that both hydrogen bonds and van der Waals forces played major roles in the association of CT-DNA-Zn(II) and HSA-Zn(II) complex formation. The displacement experiments suggested that Zn(II)-complexes primarily bound to Sudlow’s site II of HSA. The distance between the donor (HSA) and the acceptor (Zn(II) complexes) was estimated on the basis of the Forster resonance energy transfer (FRET) and the alteration of HSA secondary structure induced by the compounds were confirmed by FT-IR spectroscopy. The complexes follow the binding affinity order of I > II with DNA and II > I with HSA. Finally, Antibacterial activity of complexes I and II have been screened against gram positive and gram negative bacteria.     

Vacuum‐Assisted Growth of Low‐Bandgap Thin Films (FA0.8MA0.2Sn0.5Pb0.5I3) for All‐Perovskite Tandem Solar Cells

All‐perovskite multijunction photovoltaics, combining a wide‐bandgap (WBG) perovskite top solar cell (E_G ≈1.6–1.8 eV) with a low‐bandgap (LBG) perovskite bottom solar cell (E_G < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite solar cells lack PCE as well as stability. In this work, vacuum‐assisted growth control (VAGC) of solution‐processed LBG perovskite thin films based on mixed Sn–Pb perovskite compositions is reported. The reported perovskite thin films processed by VAGC exhibit large columnar crystals. Compared to the well‐established processing of LBG perovskites via antisolvent deposition, the VAGC approach results in a significantly enhanced charge‐carrier lifetime. The improved optoelectronic characteristics enable high‐performance LBG perovskite solar cells (1.27 eV) with PCEs up to 18.2% as well as very efficient four‐terminal all‐perovskite tandem solar cells with PCEs up to 23%. Moreover, VAGC leads to promising reproducibility and potential in the fabrication of larger active‐area solar cells up to 1 cm².     

DFT studies of acrolein molecule adsorption on pristine and Al- doped graphenes

The ability of pristine graphene (PG) and Al-doped graphene (AlG) to detect toxic acrolein (C₃H₄O) was investigated by using density functional calculations. It was found that C₃H₄O molecule can be adsorbed on the PG and AlG with adsorption energies about ?50.43 and – v30.92 kcal mol^?1 corresponding to the most stable configurations, respectively. Despite the fact that interaction of C₃H₄O has no obvious effects on the of electronic properties of PG, the interaction between C₃H₄O and AlG can induce significant changes in the HOMO/LUMO energy gap of the sheet, altering its electrical conductivity which is beneficial to sensor designing. Thus, the AlG may be sensitive in the presence of C₃H₄O molecule and might be used in its sensor devices. Also, applying an external electric filed in an appropriate orientation (almost stronger than 0.01 a.u.) can energetically facilitate the adsorption of C₃H₄O molecule on the AlG.     

Small molecule of sphingosine as a rescue of dopaminergic cells: A cell therapy approach in neurodegenerative diseases therapeutics

Multiple sclerosis (MS) patients should take medication such as fingolimod (FTY-720) for a long time, hence pharmaceutical effects on other neural cells such as dopaminergic cells are important. Dopaminergic cell line, BE(2)-M17, was treated by FTY-720 and then cell viability and genes involve in neurosurvival were investigated. It was disclosed that FTY-720 significantly stimulates Bcl2 overexpression. Whereas, it decreased intracellular reactive oxygen species production and cell membrane damage of dopaminergic cells. The increase in Bcl2/Bax ratio increased the cell metabolic activity and decreased propidium iodide-positive cells. Besides, FTY-720 induced the overexpression of CACNA1C, nNOS gene, and nitric oxide production. However, FTY-720 induced GABARA1 overexpression and eventually it could overcame to the cytotoxic effect of intracellular calcium. This cascade led to tyrosine hydroxylase and BDNF genes overexpression whereas FTY-720 did not change GDNF concentration in BE(2)-M17 cells. Concluding, it might be said that taking FTY-720 in MS patients did not induce adverse effect on dopaminergic cells.     

Laser-induced optothermal response of gold nanoparticles: From a physical viewpoint to cancer treatment application

Gold nanoparticles (GNPs)-based photothermal therapy (PTT) is a promising minimally invasive thermal therapy for the treatment of focal malignancies. Although GNPs-based PTT has been known for over two decades and GNPs possess unique properties as therapeutic agents, the delivery of a safe and effective therapy is still an open question. This review aims at providing relevant and recent information on the usage of GNPs in combination with the laser to treat cancers, pointing out the practical aspects that bear on the therapy outcome. Emphasis is given to the assessment of the GNPs’ properties and the physical mechanisms underlying the laser-induced heat generation in GNPs-loaded tissues. The main techniques available for temperature measurement and the current theoretical simulation approaches predicting the therapeutic outcome are reviewed. Topical challenges in delivering safe thermal dosage are also presented with the aim to discuss the state-of-the-art and the future perspective in the field of GNPs-mediated PTT.     

Delicate balance of electrostatic interactions and disulfide bridges in thermostability of firefly luciferase

The wild type Photinus pyralis luciferase does not have any disulfide bridge. Disulfide bridges are determinant in inherent stability of protein at moderate temperatures. Meanwhile, arginin is responsible for thermostability at higher temperatures. In this study, by concomitant introduction of disulfide bridge and a surface arginin in a mutant (A296C-A326C/I232R), the contribution of disulfide bridge introduction and surface hydrophilic residue on activity and global stability of P. pyralis luciferase is investigated. In addition to the mentioned mutant; I232R, A296C-A326C and wild type luciferases are characterized. Though addition of Arg caused stability against proteolysis but in combination with disulfide bridge resulted in decreased thermal stability compared to A296C-A326C mutant. In spite of long distance of two different mutations (A296C-A326C and I232R) from each other in the three-dimensional structure, combination of their effects on the stability of luciferase was not cumulative.