Sonodynamically induced antitumor effect of hematoporphyrin on Hepatoma 22

The ultrasonically induced cytotoxic effects of hematoporphyrin (Hp) on Hepatoma 22 (H22) cells in vitro and vivo were investigated. Tumor cells were suspended in saline and exposed to ultrasound at 1.43 MHz for up to 60s in the presence and absence of Hp. The viability of cells was evaluated by trypan blue exclusion test. The ultra-structure changes of H22 cells induced by ultrasonic irradiation were evaluated by scanning electron microscope (SEM) and transmission electron microscope (TEM). Lipid peroxidation in cell was estimated by the thiobarbicturic acid (TBA) method. Our experiments indicated that the ultrasonic intensity of 2 W/cm(2), the Hp concentration of 100 microg/ml and the ultrasound exposure time of 60s were the best conditions for sonodynamic treatment in vitro. The tumor volume and weight after the combination of Hp with ultrasound were remarkably inhibited. SEM and TEM observation found the cell ultra-structure was significantly damaged, and lipid peroxidation level remarkably increased after sonodynamic treatment. This study suggested the ultra-structural changes may play a key role in cell destruction induced by sonodynamic treatment and the biological mechanism might be involved in mediating the killing effect on H22 cells in our experiment mode.     

Membrane fluidity altering and enzyme inactivating in sarcoma 180 cells post the exposure to sonoactivated hematoporphyrin in vitro

Sonodynamic therapy (SDT) is a novel tumor therapy method. We investigated membrane fluidity, activity of the enzymes and membrane morphology in vitro post hematoporphyrin-SDT treatment. Furthermore, the potential mechanisms behind the changes in membrane fluidity and enzymic activity were discussed. Tumor cells were exposed to ultrasound at 1.75 MHz for up to 3 min in the presence and absence of hematoporphyrin. Fluorescence polarization, contents of Malonaldehyde, and levels of free fatty acid were assessed. Activity of enzymes was checked by the plumbic nitrate detection method. For the morphologic study, a scanning electron microscope was used to observe the cellular surface. Ultrasonically induced cell damage increased in the presence of HPD (from 15% to 24%). Compared with ultrasound treatment alone, the fluidity decreased from 5.037 to 3.908, malonaldehyde content and free fatty acid level increased from 0.743 nmol/mL to 0.979 nmol/mL and from 237.180 μmol/L to 730.769 μmol/L, respectively, post ultrasound combined with HPD treatment. Inactivity of adenylate cyclase and guanylate cyclase and significant deformation of the cellular surface were also observed post SDT treatment. Our results suggested that alterations in membrane modality and lipid composition played important roles in SDT-mediated inhibition of tumor growth, even inducing tumor cell death, which might be attributed to a sono-chemical activation mechanism.     

Sulfono‐γ‐AApeptides as a New Class of Nonnatural Helical Foldamer

Foldamers offer an attractive opportunity for the design of novel molecules that mimic the structures and functions of proteins and enzymes including biocatalysis and biomolecular recognition. Herein we report a new class of nonnatural helical sulfono‐γ‐AApeptide foldamers of varying lengths. The crystal structure of the sulfono‐γ‐AApeptide monomer S6 illustrates the intrinsic folding propensity of sulfono‐γ‐AApeptides, which likely originates from the bulkiness of tertiary sulfonamide moiety. The two‐dimensional solution NMR spectroscopy data for the longest sequence S1 demonstrates a 10/16 right‐handed helical structure. Optical analysis using circular dichroism further supports well‐ defined helical conformation of sulfono‐γ‐AApeptides in solution containing as few as five building blocks. Future development of sulfono‐γ‐AApeptides may lead to new foldamers with discrete functions, enabling expanded application in chemical biology and biomedical sciences.     

CRISPR-Cas12a System for Biosensing and Gene Regulation

Clustered regularly interspaced short palindromic repeats (CRISPR) is a promising technology in the biological world. As one of the CRISPR-associated (Cas) proteins, Cas12a is an RNA-guided nuclease in the type V CRISPR-Cas system, which has been a robust tool for gene editing. In addition, due to the discovery of target-binding-induced indiscriminate single-stranded DNase activity of Cas12a, CRISPR-Cas12a also exhibits great promise in biosensing. This minireview not only gives a brief introduction to the mechanism of CRISPR-Cas12a but also highlights the recent developments and applications in biosensing and gene regulation. Finally, future prospects of the CRISPR-Cas12a system are also discussed. We expect this minireview will inspire innovative work on the CRISPR-Cas12a system by making full use of its features and advantages.     

Visible-Light-Induced Vicinal Dichlorination of Alkenes through LMCT Excitation of CuCl2

This work demonstrates photoredox vicinal dichlorination of alkenes, based on the homolysis of CuCl₂ in response to irradiation with visible light. This catalysis proceeds via a ligand to metal charge transfer process and provides an exciting opportunity for the synthesis of 1,2-dichloride compounds using an inexpensive, low-molecular-weight chlorine source. This new process exhibits a wide substrate scope, excellent functional group tolerance, extraordinarily mild conditions and does not require external ligands. Mechanistic studies show that the ready formation of chlorine atom radicals is responsible for the facile formation of C−Cl bonds in this synthetic process.     

Synthesis and Herbicidal Activities of 3‐(4‐Chloro‐2‐fluoro‐5‐substituted phenyl)benzo[d][1,2,3]triazin‐4(3H)‐one Derivatives

A series of 3‐phenyl benzo[d][1,2,3]triazin‐4(3H)‐one derivatives were synthesized through the condensation of phenol E and alkyl (alkenyl, alkynyl) chlorides (bromides, iodide) or alkyl chloroacetates or N‐alkyl chloroacetamides using K₂CO₃ as the acid acceptor in N,N‐dimethylformamide. Phenol E was prepared from starting material, 5‐amino‐2‐chloro‐4‐fluorophenyl ethyl carbonate, in four steps involving in amidation, reduction, diazotization, and deprotecting‐group reaction. The herbicidal activities of the title compounds were tested against two dicotyledonous plants and two monocotyledonous plants, in which some of them exhibited high herbicidal activities against two dicotyledonous plants in preemergence and postemergence treatments. Moreover, when the dosage was decreased to 180 and 90 g/ha, compounds F1 , F8 , and F9 showed highly selective inhibitory activities against amaranth pigweed, alfalfa, asteraceae, field sowthistle, morning glory, purslane, and velvetleaf in postemergence treatment but had no herbicidal efficacy on rape except F1 , suggesting that it be possible to find a kind of herbicides to inhibit dicotyledonous weeds in the field of dicotyledonous crops with the same genus as aforementioned weeds.     

THE COURSE OF “STRUCTURAL MODEL DESIGN AND FABRICATION”

“知行统一” 的观念在教育界已深入人心,但是要做到切实履行却非易事。经过为期九年的精心打造,上海交通大学开设的创新型实践课程“结构模型设计与制作” 初步实现了“学与行” 的有机融合,教学效果显著,深受学生欢迎。本文是对该课程的总结与反思,希望对我国相关工科教学改革起到有益的借鉴作用。     

Controllable highly stereoselective reaction of in situ generated magnesium dienolate intermediates with different electrophiles

In this paper, we have described an efficient controllable stereoselective alpha-acylation and -allylation reaction of the magnesium dienolate intermediates generated in situ from the Fe(III)-catalyzed reaction between 2,3-allenoates and Grignard reagents with different electrophiles to afford 2-acylated or allylated 3( Z)- or ( E)-alkenoates depending on the nature of the electrophiles and reaction conditions. The distinct stereoselectivity may be caused by the isomerization of metallic Z-1,3-dienoate to E-1,3-dienoate via the intermediacy of anti-allylic MgCl and syn-metallic species.     

Reactivity of fullerene epoxide: preparation of fullerene-fused thiirane, tetrahydrothiazolidin-2-one, and 1,3-dioxolane

The epoxide moiety in the fullerene-mixed peroxide C60(O)(OOtBu)4 1 reacts readily with aryl isocyanates ArNCS (Ar = Ph, Naph) to form both the thiirane derivative C60(S)(OOtBu)4 and fullerene-fused tetrahydrothiazolidin-2-one. The reaction of 1 with trimethylsilyl isothiocyanate TMSNCS yields the isothiocyanate derivative C60(NCS)(OH)(OOtBu)4, the isothiocyanate and hydroxyl moieties of which could be converted to a fullerene-fused tetrahydrothiazolidin-2-one ring with alumina quantitatively. Treating 1 with BF3.Et2O yields the fullerene-fused [1,3,2]-dioxoborolane derivative C60(O2BOH)(OOtBu)4. In the presence of aldehyde or acetone, BF3.Et2O catalyzes the conversion of epoxide to fullerene-fused 1,3-dioxolane derivatives. The products are characterized by spectroscopic data. Two of the compounds are also characterized by single-crystal X-ray analysis.