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关键词： DNA  

摘要： The biological purpose of DNA is to store, replicate, and convey genetic information in cells. Progress in molecular genetics have led to its widespread applications in gene editing, gene therapy, and forensic science. However, in addition to its role as a genetic material, DNA has also emerged as a nongenetic, generic material for diverse biomedical applications. DNA is essentially a natural biopolymer that can be precisely programed by simple chemical modifications to construct materials with desired mechanical, biological, and structural properties. This review critically deciphers the chemical tools and strategies that are currently being employed to harness the nongenetic functions of DNA. Here, the primary product of interest has been crosslinked, hydrated polymers, or hydrogels. State-of-the-art applications of macroscopic, DNA-based hydrogels in the fields of environment, electrochemistry, biologics delivery, and regenerative therapy have been extensively reviewed. Additionally, the review encompasses the status of DNA as a clinically and commercially viable material and provides insight into future possibilities.

关键词： Hydrocarbons   Aromatic compounds   Composites   Materials   Molecules  

摘要： Derivatives of polycyclic aromatic hydrocarbons (PAHs) are widely used in optoelectronic materials. However, the poor solubility of unfunctionalized PAHs represents a challenge for the continued application of these compounds in emerging technologies. For organic compounds bearing one or more functional groups capable of engaging in directional hydrogen or halogen-bonding interactions, the crystal engineering toolkit currently offers many routes for optimizing the solid-state properties of these compounds. Such efforts typically lead to the discovery of periodic crystal forms that display strong adhesive intermolecular forces between the molecular fragments. By contrast, the crystal engineering of organic eutectic composites is relatively unexplored and poorly understood. Here, we report the mechanosynthesis and experimental characterization of the properties of three eutectic composites of pyrene (PYR) and anthracene (ANTH) that were discovered using the coformer bisphenol A (BPA) or phenothiazine (PTZ). The resulting eutectic composites (PYR-BPA, PYR-PTZ, and ANTH-PTZ) display significant melting point depressions ranging from 19 to 51 degrees C relative to the melting point of the PAH. The equilibrium solubilities of the composite materials were also observed to be 2-5 times greater than that of the PAH. The crystal engineering of eutectic solid forms is currently hampered by the lack of reliable empirical or theoretical tools for predicting their formation. A weighted Monte Carlo simulation was used to estimate the mixing energies and binding modes of a limited set of molecular pairs, leading to temperature-dependent interaction parameters that show promise in the selection of coformers with a high likelihood of forming eutectic composites. Complementary dispersion-corrected density functional theory (DFT-D) calculations on a set of PYR and ANTH composite models reveal that organic eutectic composites are not driven to form on the basis of favorable thermodynami

关键词： Gold compounds  

摘要： To develop new metal-based glycoconjugates as potential anticancer agents, four organometallic gold(III)-dithiocarbamato glycoconjugates of the type [Au-III(2-Bnpy)(SSC-Inp-GlcN)](PF6) (2-Bnpy: 2-benzylpyridine;Inp: isonipecotic moiety;GlcN: amino-glucose scaffold;Au3-Au6) and the corresponding model non-glycosylated counterparts [Au-III(2-Bnpy)(SSC-Inp-R)](PF6) (R: OEt (Au1), NH2 (Au2)) have been generated and characterized by means of several analytical techniques (elemental analysis, FT-IR, H-1-/C-13-NMR, ESI-MS, UV-Vis, X-ray crystallography). Their stability under physiologically-relevant conditions (PBS solution) and n-octanol/PBS distribution coefficient (D-7.4) have also been evaluated. Gold(III) glycoconjugates showed an antiproliferative effect against ovarian carcinoma A2780 cells, with GI(50) values in the low micromolar range. Remarkably, their cell growth inhibitory effect increases upon the addition of a glucose transporter 1 (GLUT1) inhibitor, thus ruling out the involvement of GLUT1 in their transport inside the cell. Additional mechanistic studies have been carried out in A2780 cells, supporting the hypothesis of a facilitated diffusion mechanism (possibly mediated by glucose transporters other than GLUT1), and revealing their capability to act as topoisomerase I and II inhibitors and to disrupt mitochondrial membrane integrity, leading to the generation of ROS, thus resulting in the promotion of oxidative stress and, eventually, cell death.

关键词： Rhenium   Benzophenone thiosemicarbazone   X-ray crystallography   Spectroscopy   DFT calculations   Electrochemistry  

摘要： fac-[Re(CO)(3)(kappa(2)-N-im,S-bptsc)Cl] (2), isolated from the reaction between Re(CO) 5 Cl and benzophenone thiosemicarbazone, bptsc, (1) in refluxing toluene in air, is the first Re compound of 1 and is the second Re(CO)(3)Cl compound of kappa(2)-N-im,S-coordinated ligand (im = imine). The authenticity of 2 was established from the results of its elemental composition, spectroscopic measurements, and X-ray crystallographic analysis. Single crystals of 2 grown from DMF are in the monoclinic space group P2(1)/c. The asymmetric unit of 2 revealed pseudo-octahedral coordination about Re. Two carbonyl C atoms, an imine N atom and a thione S atom occupy the equatorial sites and the axial sites are occupied by a carbonyl C atom and a Cl atom. The kappa(2)-N,S-coordination of 1 to Re forms a semi-planar five-membered [Re-N-N-C-S] metallocyclic ring. The extended structure disclosed stacks of molecules interlocked via a web of N-H center dot center dot center dot X (X = Cl or O), S center dot center dot center dot S and C-H center dot center dot center dot pi interactions. DFT calculations divulged facile delocalization of electron density in the molecule and interatomic distances and angles in good agreement with the solid state structure. Electrochemical measurements on 2 in CH3CN and DMF revealed sequential irreversible electron transfers pointing to structural changes due to electrochemically induced thione-thiol tautomerization of the thioamide moiety. Plausible mechanisms for the oxidative and reductive electrochemical decomposition of 1 and 2 are reported. The proposed mechanisms are in good agreement with those reported in the literature for closely related compounds. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Ceria nanoparticles   Reduction-active ions   Redox reactions   Dissolution   Reactive oxygen species   Cytotoxicity  

摘要： The physicochemical transformations as well as the redox reaction-induced toxicity changes of ceria nanoparticles (CeO2 NPs) in reducing conditions is extremely lacking. Herein, the behaviors, chemical modifications and toxicity of CeO2 NPs in the presence of reduction-active ions (namely Fe2+ and S2-) were investigated, with a particular emphasis on the cytotoxicity mechanism associated with their physicochemical transformations. The presence of Fe2+ and S2- differently altered the surface properties and toxicity of CeO2 NPs. Redox reactions with Fe2+ led to form small aggregates, boosted the reduction of CeIVO2 and enhanced dissolved Ce3+ concentration. Moreover, CeO2 NPs possessed a high affinity for Escherichia coli (E. coli) and induced the generation of ?OH abiotically after reaction with Fe2+, provoking serious disruption of cell membranes and causing high toxicity to E. coli. In contrast, the amending of S2- protected E. coli from direct contact with CeO2 NPs by creating new Ce2S3 precipitated on the surface, accelerating the aggregation of NPs and reducing the concentration of dissolved Ce3+. This study suggested that the chemical interactions between the reactive surfaces of CeO2 and reductionactive ions highly determined the stability and cytotoxicity of CeO2 NPs, which provides fundamental insights into the environmental risks of CeO2 NPs.

关键词： Muscular steatosis   Loin   Beef quality   Fatty replacement   Muscle fiber characteristics  

摘要： To understand muscular steatosis observed in beef carcasses, physicochemical and histochemical characteristics were compared between abnormal (massive fatty replaced) and normal regions of beef striploin. Fat content in the abnormal region (48.02%) was approximately twice than that in the normal region (22.01%). However, fatty acids did not show significant (P 0.05) higher in the abnormal region. However, other meat quality traits were not significantly (P 0.05) different between the two regions. Massive accumulation of adipocytes was accompanied by muscle fiber atrophy regardless of muscle fiber types. Without a change in total muscle fiber density, oxidative fiber composition was significantly increased, whereas glycolytic fiber composition was decreased (P < 0.05). These findings suggest that adipogenic transdifferentiation and muscle fiber type switching can occur within the muscle due to muscular steatosis.

关键词： Hull-less barley   beta-Glucan extraction   Physicochemical properties  

摘要： In this study, four extraction methods, including ultrasonic extraction (UE), hot water extraction (HWE), microwave extraction (ME), and microwave-assisted ultrasonic extraction (MUE) were utilized to extract beta-glucan from hull-less barley bran. Extraction yields and physicochemical properties of beta-glucans extracted by different methods were investigated. The MUE displayed a highest extraction yield (2.16%) within shorter extraction time. Besides, beta-glucans extracted by MUE (MUE-G) had higher number-average molecular weight (M-n) (3.415 x 10(5)), whereas beta-glucans extracted by UE (UE-G) showed lower M-n (2.257 x 10(5)) as compared to other methods. Accordingly, apparent viscosity of MUE-G was highest, while water solubility index of UE-G was highest (34.18-88.81%) at tested temperature ranges (25-95 degrees C). The MUE-G shower stronger foam stability and emulsifying properties and weaker foaming capability, while UE-G exhibited stronger foaming capability. The foaming capability and emulsifying properties of beta-glucan products were better in neutral solutions (pH = 7) than in the acidic (pH = 4) and alkaline (pH = 9). (c) 2021 Elsevier B.V. All rights reserved.

关键词： 物理化学   吉布斯自由能G   吉布斯自由能变化值ΔG   计算公式小结  

摘要： 封闭体系中吉布斯自由能变化值ΔG的计算是大学物理化学课程中很重要的一个内容,ΔG其大小既可以用于判断简单状态变化过程的方向和限度,又可以用于判断化学反应的方向和限度,是最实用的判据之一,但是由于计算ΔG的公式很多且不同过程中计算ΔG使用的公式不尽相同,因此部分学生对此部分内容的学习感到十分困难。本文通过讲解吉布斯自由能由来,归纳不同过程ΔG的计算公式并适当举例,使学生能更好的掌握不同过程ΔG的计算方法。

关键词： Biscoumarin   Ethanol   DMSO   Apparent molar volume   Apparent molar isentropic compression   Jones-Dole coefficients  

摘要： Density, speed of sound and viscosity for varying concentrations of 3,3-(phenylmethylene)bis(4-hydroxy-2H-chromen-2-one) in DMSO and solvent media containing (5, 10, 15, 20, 25)% w/w of ethanol in DMSO have been measured. These properties have been deliberated over a wide range of temperatures ranging from 288.15 K to 313.15 K and at p=0.1 MPa. Fromthe experimental data, different derived parameters like apparent molar volume (V-phi), limiting apparent molar volume (V-phi(0)), apparent molar isentropic compression (K-phi,K-s), limiting apparent isentropic compression (K-phi,s(0)), transfer volumes, limiting apparent molar expansibility (E-phi(0)), coefficient of thermal expansion (alpha), Hepler's constant, viscosity coefficients (A and B), viscosity B-coefficient of transfer and dB/dT values have been determined. Further, the results have been expounded in terms of solute-solute and solute-solvent interactions and structure-making ability of solute molecules in different solvent systems of study. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Calcium phosphate ceramics   Droplet microfluidics   Bone graft substitutes   Mesenchymal stromal cells  

摘要： Affordable and therapeutically effective biomaterials are required for successful treatment of orthopaedic critical-size bone defects. Calcium phosphate (CaP) ceramics are widely used for bone repair and regen-eration, however, further optimization of their properties and biological performance is still required. To improve the existing CaP bone graft substitutes, novel synthesis and production approaches are needed that provide a fine control over the chemical and physical properties and versatility in the delivery for-mat. In this study, a microfluidic strategy for production of CaP microparticles with different sizes derived from highly monodisperse droplets is proposed for the controlled synthesis of bioactive CaP ceramics. Mi-crofluidic droplets, that served as microreactors for CaP precipitation, allowed the production of different CaP phases, as well as strontium-substituted CaP. By varying the concentration of the precursor solution, microparticles with different porosity were obtained. The droplet microfluidic system allowed direct vi-sualization and quantification of the reaction kinetics. Upon production and purification of the micropar-ticles, the biocompatibility and bioactivity were tested in vitro using human mesenchymal stromal cells (hMSCs). Cell attachment was analysed by imaging of the cytoskeleton and focal adhesions Moreover, cell proliferation, metabolic activity, alkaline phosphatase activity and mRNA expression of a set of os-teogenic markers were quantified. We demonstrated that droplet microfluidics is a functional technique for the synthesis of a range of bioactive CaP-based ceramics with controlled properties. Statement of significance Calcium phosphate (CaP) ceramics are widely applied synthetic biomaterials for repair and regeneration of damaged bone;yet, CaP bone graft substitutes require further improvement to fully replace natural bone grafts in challenging clinical situations. To this end, novel synthesis and production approaches a