Double-edged effects caused by magnesium ions and alkaline environment regulate bioactivities of magnesium-incorporated silicocarnotite in vitro

Magnesium(Mg)is an important element for its enhanced osteogenic and angiogenic properties in vitro and in vivo,however,the inherent alkalinity is the adverse factor that needs further attention.In order to study the role of alkalinity in regulating osteogenesis and angiogenesis in vitro,magnesium-silicocarnotite[Mg-Ca5(PO4)2SiO4,Mg-CPS]was designed and fabricated.In this study,Mg-CPS showed better osteogenic and angiogenic properties than CPS within 10wt.%magnesium oxide(MgO),since the adversity of alkaline condition was covered by the benefits of improved Mg ion concentrations through activating Smad2/3-Runx2 signaling pathway in MC3T3-E1 cells and PI3K-AKT signaling pathway in human umbilical vein endothelial cells in vitro.Besides,provided that MgO was incorporated with 15wt.%in CPS,the bioactivities had declined due to the environment consisting of higher-concentrated Mg ions,stronger alkalinity and lower Ca/P/Si ions caused.According to the results,it indicated that bioactivities of Mg-CPS in vitro were regulated by the double-edged effects,which were the consequence of Mg ions and alkaline environment combined.Therefore,if MgO is properly incorporated in CPS,the improved bioactivities could cover alkaline adversity,making Mg-CPS bioceramics promising in orthopedic clinical application for its enhancement of osteogenesis and angiogenesis in vitro.

Optimized sintering and mechanical properties of Y-TZP ceramics for dental restorations by adding lithium disilicate glass ceramics

The novel dental ceramics can be fabricated at lower temperatures when sol-gel derived lithium disilicate glass ceramics(LDGC)was used as an additive for yttria stabilized tetragonal zirconia polycrystalline(Y-TZP)ceramics.The effect of LDGC on the sintering,mechanical,and translucent properties of Y-TZP ceramics was investigated in the present study.The results showed that the LDGC additive effectively improved the densification of Y-TZP at 1100℃,which was much lower than the sintering temperature for pure Y-TZP.When sintered at 1100℃,the Y-TZP with 1 wt%LDGC reached a relative density of 95.45%,and prossessed a flexural strength of 482.4 MPa and a fracture toughness of 5.94 MPa-m12.Moreover,its translucency was also improved.While,the addition of LDGC could result in an escape of yttrium atoms from the grain lattice of zirconia,which induced the tetragonal-monoclinic transformation of zirconia and abnormal growth of monoclinic grains.The escaped yttrium atoms diffused into the intergranular glass phase.The results indicated that the novel Y-TZP-LDGC ceramics has a great potential to be used for all-ceramic restorations.

Asymmetric Intramolecular Hydroalkoxylation of Unactivated Alkenes Catalyzed by Chiral N-Triflyl Phosphoramide and TiCl4

By using a combination of a chiral/V-triflyl phosphoramide and TiCl4 as the catalyst,a new process for asymmetric intramolecular hydroalkoxylation of unactivated alkenes was developed,producing various chiral tetrahydrofuran derivatives in 51%—99% yields with 30%—71%ee's.

Advanced protein adsorption properties of a novel silicate-based bioceramic: A proteomic analysis

Silicate bioceramics have been shown to possess excellent cytocompatibility and osteogenic activity,but the exact mechanism is still unclear.Protein adsorption is the first event taking place at the biomaterial-tissue interface,which is vital to the subsequent cellular behavior and further influence the biomaterial-tissue interaction.In this work,the protein adsorption behavior of a novel CPS bioceramic was evaluated using the proteomics technology.The results showed that CPS adsorbed more amount and types of serum proteins than HA.FN1 and IGF1 proteins selected from proteomics results were validated by Western-blot experiment.Pathway analysis also revealed mechanistic insights how these absorbed proteins by CPS help mediate cell adhesion and promotes osteogenic activity.Firstly,the dramatically enhanced adsorption of FN1 could greatly promote cell adhesion and growth.Secondly,IGF1 was uniquely adsorbed on CPS bioceramic and IGF1 could activate Rap1 signaling pathway to promote cell adhesion.Thirdly,the increased adsorption of FN1,IGF1 and COL1A2 proteins on CPS explains its better ability on bone regeneration than HA.Fourthly,the increased adsorption of IGF1,CHAD,COL2A1 and THBS4 proteins on CPS explains its ability on cartilage formation.Lastly,the increased adsorption of immunological related proteins on CPS may also play a positive role in bone regeneration.In addition,CPS had a much better cell adhesion ability than HA,proving that more adsorbed proteins really had a positive effect on cell behavior.The more adsorbed proteins on CPS than HA might indicated a better bone regeneration rate at early stage of implantation.

Discovery of New Thioviridamide-Like Compounds with Antitumor Activities

Thioviridamide is a structurally unique compound with potent antitumor activity.The biosynthesis of thioviridamide follows a typical pathway as ribosomally synthesized and post-transiationally modified peptides,making the genome mining-based discovery of thioviridamide-like compounds rational.Taking advantage of the linkage between the precursor peptide and the metabolite skeleton,we identified a new biosynthetic gene cluster in Streptomyces sp.NRRL S-87 that could encode thioviridamide analogues.Overexpression of the whole gene cluster led to the isolation and structure elucidation of TVA-YJ-4 and TVA-YJ-5,two novel thioviridamide-like compounds featuring N-terminal capping groups.Chemical screening of the fermentation extracts also detected TVA-YJ-6,another new thioviridamide-like compound with representative methionine sulfoxide.Detailed analysis further revealed that these structural modifications were introduced during the compound extraction process instead of through genuine enzymatic reactions.TVA-YJ-4 and TVA-YJ-5 display slightly reduced cytotoxic activities against a panel of tumor cell lines in comparison with their parental natural product,TVA-YJ-2.Our work will expand the membership of this rare class of compounds and promote related biosynthetic studies.

Deoxygenative alkylation of tertiary amides using alkyl iodides under visible light

It is an unceasing goal for organic chemists to develop new catalytic methodologies for functional group transformations of widespread molecular structures. Amides are readily available from simple and reliable reactions, which are common structural units found in biologically active compounds. Consequently, they are attractive to be exploited in amine synthesis by reductive cross coupling. However, deoxygenative functionalization of amides is a long-standing challenge owing to the inertness of the resonance-stabilized amide C=O bond. In this work, a deoxygenative alkylation strategy was demonstrated, which combines amides and alkyl iodides to build structurally diverse tertiary alkylamines in a single step. Compared with previous deoxygenative alkylation of amides using organometallic reagents as functional partner, this work uses stable and easily available alkyl halides as functionalization reagents. The versatile and flexible strategy plus structural and functional diversity of readily available amides and alkyl iodides renders it highly appealing for the streamlined synthesis of tertiary amines and would be of much interest in areas such as pharmaceutical and agrochemical research.

Primary amine-functionalized mesoporous phenolic resin as an effective and stable solid base catalyst for Knoevenagel reactions in water

A primary amine functionalized ordered mesoporous phenolic resin(NH2-MPR)was obtained by an evaporationinduced self-assembly method.The as-prepared NH2-MPR material possessed large surface area and ordered twodimensional hexagonal mesoporous structure.Also,the amine groups were well-dispersed in the mesoporous channels.It can act as an efficient solid base to promote Knoevenagel condensation of various aldehydes with ethyl cyanoacetate in water with high conversion and selectivity.This excellent performance was attributed ordered mesopores and hydrophobic pore surface,which resulted in the decreased the interference of water solvent and the increased active sites accessibility.Noted that it was comparable with homogenous base catalysts in the water-medium Knoevenagel condensation reaction,and it can be reused for at least five times without significant reduction in the catalytic efficiency.

Biomimetic Chiral Pyridoxal and Pyridoxamine Catalysts

What is the most favorite and original chemistry developed in your research group? Vitamin B6-based biomimetic asymmetric catalysis. How do you get into this specific field? Could you please share some experiences with our readers? Enzymatic transformations are characterized by high efficiency, specific selectivities, and mild conditions, which attracts me to do some chemistry related to biological systems.