New Approach to Structure–Property Correlations of Different Films of Sorbitan Esters and Their Self-Assembly into Viscoelastic Monolayers

This publication is focused on the structural origin of viscoelasticity in Langmuir monolayers. To improve the understanding of the structural origin of viscoelasticity of surfactant films, we systematically studied interfacial films of different sorbitan esters with saturated (Span 60 and 65) and unsaturated (Span 80 and 85) paraffin chains by means of surface rheology, Langmuir isotherms, X-ray reflectometry (XRR), and Brewster angle microscopy (BAM). The results of two-dimensional shear rheological measurements revealed the existence of temporarily cross-linked networks. In dynamic BAM experiments, we observed a swinging motion of the monolayers as a result of a sudden externally initiated mechanical perturbation. The viscoelastic film response, which relaxed with time as the external force vanished, could be traced back to the presence of foam-like supramolecular structures that interlinked solid-condensed domains. The temperature dependence of the elastic response implied that the solid domains decomposed at temperatures close to the bulk melting point of Span 60 and Span 65. We concluded that insoluble surfactants formed solid domains at the interface, which were linked with each other by nonsolid areas, giving viscoelastic films. These newly discovered insights into coherent film formations could provide new opportunities for designing mechanically stable surfactant interfaces.     

Synthesis of Long-Chain β-Lactones and Their Antibacterial Activities against Pathogenic Mycobacteria

In the quest for new antibacterial agents, a series of novel long- and medium-chain mono- and disubstituted β-lactones was developed. Their activity against three pathogenic mycobacteria—M. abscessus, M. marinum, and M. tuberculosis—was assessed by the resazurin microtiter assay (REMA). Among the 16 β-lactones synthesized, only 3-hexadecyloxetan-2-one (VM005) exhibited promising activity against M. abscessus, whereas most of the β-lactones showed interesting activities against M. marinum, similar to that of the classical antibiotic, isoniazid. Regarding M. tuberculosis, six compounds were found to be active against this mycobacterium, with β-lactone VM008 [trans-(Z)-3-(hexadec-7-en-1-yl)-4-propyloxetan-2-one] being the best growth inhibitor. The promising antibacterial activities of the best compounds in this series suggest that these molecules may serve as leads for the development of much more efficient antimycobacterial agents.     

红色红曲菌组蛋白去乙酰化酶MrSir2的原核表达及活性分析

根据基因组序列信息,利用cDNA末端快速扩增技术(rapid-amplification of cDNA ends,RACE)得到了红色红曲菌中组蛋白去乙酰化酶mrsir2基因的完整cDNA序列,其编码序列(coding sequence,CDS)为1539 bp,编码512个氨基酸,含有一个SIR2蛋白保守结构域。根据大肠杆菌的密码子的偏好性对mrsir2序列进行优化,优化后的序列与p ET-28b载体连接后转入宿主菌E.coli BL21中进行IPTG诱导表达,并优化表达条件。实验结果表明:在16℃条件下用终浓度为0.25 mM的IPTG诱导培养16 h后,目的蛋白Mr Sir2可溶性表达效果良好。Ni2+柱亲和层析纯化后的Mr Sir2重组蛋白在SDS-PAGE上显示为一条约75 ku大小的条带,蛋白定量浓度达1.97 mg/mL,经Western blot鉴定为目的蛋白,测定酶活为78.5(OD/min/mg),780μM的二氢香豆素(dihydrocoumarin,DHC)对Mr Sir2蛋白的酶活抑制率为47%。Mr Sir2蛋白的可溶性表达为全面了解其酶学特征提供了材料,也为体外分析蛋白相互作用奠定了基础。     

Isolation,purification, and antioxidant activities of polysaccharides from Ziziphus Jujuba cv. Muzao

In the present study, crude polysaccharides from Ziziphus Jujuba cv. Muzao were isolated and purified using DEAE cellulose-52 and Sephadex G-100 size-exclusion chromatography; four fractions were collected, namely GZMP-1, GZMP-2, GZMP-3, and GZMP-4. The molecular weights of these four fractions were measured to be 111.2, 95.1, 84.2, and 571.4 kDa, respectively, using high-performance gel permeation chromatography. Gas chromatography analysis of the monosaccharide composition confirmed that GZMP-1 was composed of rhamnose, arabinose, glucose, and galactose. Rhamnose, arabinose, and galactose were the main components present in GZMP-2 and GZMP-3, whereas GZMP-4 was composed of only rhamnose and arabinose. Scanning electron microscopy showed relatively smooth surfaces for GZMP-1 and GZMP-4, whereas GZMP-2 and GZMP-3 had more folds on their surfaces. Fourier transform infrared spectroscopy analyses indicated that GZMP-1 and ZMP mainly had α-type glycosidic linkages. The in vitro antioxidant activities of the polysaccharides revealed that jujube polysaccharides exhibit remarkable antioxidant activity, and can scavenge DPPH radical and OH radical in a concentration-dependent manner. The results of this work suggest that polysaccharides from Z. Jujuba cv. Muzao have potential to be used as functional food and in the development of natural antioxidant drug carriers.     

Improved reversible dehydrogenation properties of MgH2 by the synergetic effects of graphene oxide-based porous carbon and TiCl3

In this study, we used a combination of graphene oxide-based porous carbon (GC) and titanium chloride (TiCl₃) to improve the reversible dehydrogenation properties of magnesium hydride (MgH₂). Examining the effects of GC and TiCl₃ on the hydrogen storage properties of MgH₂, the study found GC was a useful additive as confinement medium for promoting the reversible dehydrogenation of MgH₂. And TiCl₃ was an efficient catalytic dopant. A series of controlled experiments were carried out to optimize the sample preparation method and the addition amount of GC and TiCl₃. In comparison with the neat MgH₂ system, the MgH₂/GC-TiCl₃ composite prepared under optimized conditions exhibited enhanced dehydrogenation kinetics and lower dehydrogenation temperature. A combination of phase/microstructure/chemical state analyses has been conducted to gain insight into the promoting effects of GC and TiCl₃ on the reversible dehydrogenation of MgH₂. Our study found that GC was a useful scaffold material for tailoring the nanophase structure of MgH₂. And TiCl₃ played an efficient catalytic effect. Therefore, the remarkably improved dehydrogenation properties of MgH₂ should be attributed to the synergetic effects of nanoconfinement and catalysis.     

Phytochemical Composition and in Vitro Analysis of Nopal (O. Ficus-Indica) Cladodes at Different Stages of Maturity

This study aimed to determine the phytochemical profile and nutraceutical properties of nopal cladodes (Opuntia ficus-indica) at different stages of maturity. Medium-age cladodes showed the highest total saponins, phytosterols, and indigestible fiber, as well as the highest in vitro antioxidant capacity and digestive enzymes inhibitory activity. Furthermore, these cladodes presented the highest content of p-hydroxybenzoic acid, p-coumaric acid, rutin, narcissin, nicotiflorin, β-sitosterol, and sitosteryl-3-β-glucopyranoside, as well as several amino acids, organic acids, and fatty acids. Whereas young cladodes contained the highest concentration of condensed and hydrolyzable tannins. These results demonstrated that maturity affects the nutritional and nutraceutical properties of nopal cladodes.     

Study of the Antioxidative Properties of Several Amino Acid-Type Surfactants and their Synergistic Effect in Mixed Micelle

Cysteine and methionine, two sulfur-containing amino acids (AA), were introduced in their surfactant forms as potential antioxidants. The antioxidative (AOX) properties of lauroyl methionine (C12-Met) and lauroyl cysteine (C12-Cys) was investigated by means of the oxygen radical absorbance capacity assay. Both the surfactants exhibited excellent AOX behavior at the premicellar state and micellar medium. The AOX behavior was found to be comparable for both the surfactants at their premicellar states. However, in micellar medium, C12-Met showed better AOX property than C12-Cys. The AOX power of the surfactants was compared with other previously developed AA-type surfactants. The order of the AOX power was found to be: C12-tryptophan > C12-tyrosine ≈ C12-methionine ≈ C12-cysteine > C12-histidine at the premicellar state and C12-tryptophan > C12-tyrosine > C12-methionine > C12-cysteine > C12-histidine at the micellar state. C12-Cys displayed lower AOX property in micellar medium due to its dimer formation tendency. Based on the HPLC and UPLC-Q-TOF-MS analysis, the dimer formation of C12-Cys was found to be accelerated due to the micellar environment and results into negative synergistic effect on other aromatic AA-type surfactants. However, the presence of C12-His in the micellar solution of C12-Cys resulted no synergistic effect due to stronger H-bonding between the surfactants and resulting less dimer formation.     

In Silico Study on Tumor-Size-Dependent Thermal Profiles inside an Anthropomorphic Female Breast Phantom Subjected to Multi-Dipole Antenna Array

Electromagnetic hyperthermia as a potent adjuvant for conventional cancer therapies can be considered valuable in modern oncology, as its task is to thermally destroy cancer cells exposed to high-frequency electromagnetic fields. Hyperthermia treatment planning based on computer in silico simulations has the potential to improve the localized heating of breast tissues through the use of the phased-array dipole applicators. Herein, we intended to improve our understanding of temperature estimation in an anatomically accurate female breast phantom embedded with a tumor, particularly when it is exposed to an eight-element dipole antenna matrix surrounding the breast tissues. The Maxwell equations coupled with the modified Pennes’ bioheat equation was solved in the modelled breast tissues using the finite-difference time-domain (FDTD) engine. The microwave (MW) applicators around the object were modelled with shortened half-wavelength dipole antennas operating at the same 1 GHz frequency, but with different input power and phases for the dipole sources. The total input power of an eight-dipole antenna matrix was set at 8 W so that the temperature in the breast tumor did not exceed 42 °C. Finding the optimal setting for each dipole antenna from the matrix was our primary objective. Such a procedure should form the basis of any successful hyperthermia treatment planning. We applied the algorithm of multi for multi-objective optimization for the power and phases for the dipole sources in terms of maximizing the specific absorption rate (SAR) parameter inside the breast tumor while minimizing this parameter in the healthy tissues. Electro-thermal simulations were performed for tumors of different radii to confirm the reliable operation of the given optimization procedure. In the next step, thermal profiles for tumors of various sizes were calculated for the optimal parameters of dipole sources. The computed results showed that larger tumors heated better than smaller tumors; however, the procedure worked well regardless of the tumor size. This verifies the effectiveness of the applied optimization method, regardless of the various stages of breast tumor development.