Biodegradation-induced surface change of polymer microspheres and its influence on cell growth

Biodegradable microspheres were fabricated by poly(?-caprolactone) (PCL) homopolymer and poly(?-caprolactone-b-ethylene oxide) (PCL-b-PEO) amphiphilic block copolymer. The regulation of microsphere surface morphology was successfully achieved by controlled enzymatic degradation. The morphological changes induced by biodegradation and their influences on the growth of MG-63 human osteosarcoma cells were studied. Results based on the evaluation of cytotoxicity and the morphological observation of MG-63 cells cultivated on microspheres showed better growth of cells on the surface of degraded microspheres than on the surface of those undegraded microspheres no matter they were fabricated by homopolymers or copolymers. The influences of morphological changes of microsphere surface before and after biodegradation on MG-63 cell growth were discussed. The results of this work indicated that the biodegradation-induced morphological changes of microspheres could be well controlled and were favorable for MG-63 cell attachment and proliferation.     

Machilusides A and B: structurally unprecedented homocucurbitane glycosides from the stem bark of Machilus yaoshansis

Two structurally novel homocucurbitane triterpenoid glycosides, machilusides A (1) and B (2), possessing an unprecedented C(36) skeleton with a D-fructose moiety incorporated into a cucurbitane nucleus forming unique cage-like tricyclic ring moieties, were isolated from the stem bark of Machilus yaoshansis. Their structures were determined by spectroscopic methods. Both compounds exhibited nonselective cytotoxic activities against several human cancer cell lines. The biosynthetic pathway of 1 and 2 was postulated.     

Pampas grass-inspired FeOOH nanobelts as high performance anodes for sodium ion batteries

High-performance materials are the key to developing new alternative energy-storage systems[1-4].Sodium ion batteries(SIBs)are regarded as the promising large-scale electric energy storage owing to the high abundance and low cost of sodium resources[1,5-9].However,the sluggish kinetics of Na⁺caused by the large-sized Na⁺(1.02A)result in the lower energy density and unsatisfactory electrochemical properties[10-14].     

叔丁基取代的环戊二烯基钛、锆、铪二氯化物的合成及催化乙烯聚合

(tBuC5H4 ) 2 MCl2 (M =Ti(1a) ,Zr(1b) ,Hf(1c) )和 (tBu2 C5H3 ) 2 MCl2 (M =Ti(2a) ,Zr(2b) ,Hf(2c) )可以通过单叔丁基环戊二烯基锂或双叔丁基环戊二烯基锂与MCl4 (M =Ti,Zr,Hf)在四氢呋喃中反应制备得到 ,用IR、1H NMR和EI MS对这些化合物进行了表征 .采用X光单晶结构分析测定了 (tBuC5H4 ) 2 HfCl2 的晶体结构 .六个化合物均具有一定的催化乙烯聚合活性     

邻苯二酚紫-示波计时电位法测定天然水中不同形态铝

报道邻苯二酚紫-示波计时电位法分别在酸性和碱性条件下直接检测天然水中的无机单核铝和总单核铝浓度。并用该法测定了水样中的总铝,有机单核铝和酸溶态铝,从而实现了天然水中5种Al形态的电化学测定。测定了20多个实际水样,与Driscoll方法进行了对照,结果基本一致。     

一种新型C60-硫醚衍生物分子在金表面上的自组装

报导了一种新型C60 硫醚分子在金表面上自组装膜的形成,并通过接触角、扫描隧道显微术（STM）、X射线光电子能谱（XPS）、电化学和光电化学手段对其进行表征.高分辩STM形貌图证明,在Au(111)基底上C60基团存在并直观显示出特殊的单层膜结构. XPS分析表明,这一新型C60 硫醚分子是通过金硫键固定在金表面上的,并且在组装过程中存在分子内碳硫键断裂步骤.     

掺杂TiO2纳米粉的合成、表征及催化性能研究

 考察了制备方法对掺杂Fe2O3,ZrO2或SnO2的TiO2纳米粉的XRD谱及催化性能的影响．结果表明,用共沉淀法制备的Fe2O3·TiO2对其XRD谱强度的影响较大,而负载法制备Fe2O3／TiO2对其XRD谱的强度无影响;两种方法制备的掺杂ZrO2或SnO2的TiO2样品对XRD谱均无影响．TEM结果表明,TiO2纳米粉的晶粒均匀,粒径为14～18nm．苯酚水溶液的光催化氧化分解反应结果表明,与TiO2样品相比,负载型Fe2O3／TiO2的催化活性明显较高,但ZrO2／TiO2,SnO2／TiO2和共沉淀型Fe2O3·TiO2的催化活性变化不大．可以认为,对掺杂Fe2O3的TiO2催化剂,负载法是较好的制备方法．     

Ligand effect in the synthesis of hyperbranched polymers via copper-catalyzed azide-alkyne cycloaddition polymerization (CuAACP)

Copper-catalyzed azide-alkyne cycloaddition polymerization (CuAACP) of AB₂ monomers demonstrated a chain-growth mechanism without any external ligand because of the complexation of in situ formed triazole groups with Cu catalysts. In this study, we explored the use of various ligands that affected the polymerization kinetics to tune the polymers’ molecular weights and the degree of branching (DB). Eight ligands were studied, including polyethylene glycol monomethyl ether (PEG₃₅₀, M_n = 350), tris(benzyltriazolylmethyl)amine (TBTA), 2,6-bis(1-undecyl-1H-benzo[d]imidazol-2-yl)pyridine (Py(DBim)₂), 2,2′-bipyridyl (bpy), 4,4′-di-n-nonyl-2,2′-bipyridine (dNbpy), N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA), N,N,N′,N″,N″-penta(n-butyl)diethylenetriamine (PBuDETA), and N,N,N′,N″,N″-pentabenzyldiethylenetriamine (PBnDETA). All ligands except PEG₃₅₀ exhibited stronger coordination with Cu(I) than the polytriazole polymer, which freed the Cu catalyst from polymers and resulted in dominant step-growth polymerization with simultaneous chain-growth feature. Meanwhile, the use of PEG₃₅₀ ligand retained the confined Cu in the polymer, demonstrating a chain-growth mechanism, but lower polymer molecular weights as compared with the no-external-ligand polymerization. Results indicated that aliphatic substituent groups on ligands had little effect on the molecular weights and DB of the polymers, but rigid aromatic substituent groups decreased both values. By varying the ligand species and amounts, hyperbranched polymers with DB value ranging from 0.53 ([TBTA]₀/[Cu]₀ = 5) to 0.98 ([PMDETA]₀/[Cu]₀ = 2) have been achieved. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2238–2244