3D inverted opal hydrogel scaffolds with oxygen sensing capability

The measurement of local oxygen level in 3D cell culture is desired but remains as a challenge problem. We developed a 3D cell scaffold with luminescence-based oxygen sensing capability that opens the possibility of 3D mapping of oxygen level during cell growth. Hydrogel inverted opal scaffold was prepared by photo-polymerization of poly(2-hydroxyethyl methacrylate (pHEMA) and poly(methacryloyloxy)ethyl-trimethylammonium chloride (pMEATAC) monomer using close-packed bead assembly as template. Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium chloride (Ru(dpp)(3)), was coated on the pHEMA-pMEATAC 3D scaffolds by layer-by-layer (LBL) assembly. pHEMA-pMEATAC copolymer was coated on top of the Ru(dpp)(3) layer as a protection layer. The fluorescence emission of Ru(dpp)(3) can be dynamically quenched by oxygen. By measuring the emission intensity of the scaffold, the local oxygen level can be monitored. The hydrogel scaffolds are transparent, and thus 3D fluorescence intensity can be mapped by confocal microscopy. Human bone marrow stromal cells HS-5 were successfully cultured on the oxygen sensing scaffold, and the observed Ru(dpp)(3) emission intensity from the scaffold was stronger in cell rich area, which indicates a lower oxygen level due to the consumption of the cells.     

与胶原特异性结合的BMP2模拟肽/PLGA 3D打印复合支架的制备及成骨诱导活性

将胶原绑定结构域(CBD)多肽序列与骨形态发生蛋白2模拟肽(BMP2-MP)序列连接制备具有胶原绑定能力的CBD-BMP2-MP, 再将CBD-BMP2-MP与聚丙交酯-乙交酯/胶原(PLGA/COL)3D打印支架相结合, 以支架表面的胶原成分为媒介, 将CBD-BMP2-MP更有效地固定于骨修复材料上, 达到对其进行改性的目的. 利用扫描电子显微镜(SEM)、 电子万能试验机和接触角测量仪对复合支架表面形貌、 力学强度和亲水性等材料学性能进行评价. 用荧光成像法评测 CBD-BMP2-MP及BMP2-MP与支架材料的结合能力. 在各组支架材料表面接种MC3T3-E1细胞进行体外培养, 采用CCK-8、 鬼笔环肽荧光染色、 茜素红染色及qPCR综合评价细胞在材料表面的黏附、 增殖和成骨分化等细胞行为, 研究CBD-BMP2-MP修饰的3D多孔PLGA/COL复合支架的生物学性能. 研究结果表明, 利用3D打印技术制备的多孔支架具有形貌可控的孔隙结构, 为细胞生长创造更有利的细胞微环境, 支架表面胶原成分的加入提高了支架材料的亲水性, 同时对支架材料本身的力学性能无任何影响, 提高了复合支架本身的生物相容性. 与普通BMP2-MP相比, CBD-BMP2-MP具有更好的胶原绑定能力, 与复合支架的结合更稳定, 提高了PLGA/COL复合支架对BMP2-MP的负载能力. 支架表面负载CBD-BMP2-MP后具有极强的促细胞成骨分化能力. MC3T3-E1细胞表现出更高的钙沉积能力, 并且成骨分化相关基因Runx2, ALP, COL-I及OPN等水平也有了明显提升. 表明CBD-BMP2-MP多孔复合支架具有良好的生物相容性和成骨诱导活性, 在骨组织修复领域具有良好的应用前景.     

The central proline rich region of POB1/REPS2 plays a regulatory role in epidermal growth factor receptor endocytosis by binding to 14-3-3 and SH3 domain-containing proteins

Background  

The human POB1/REPS2 (Partner of RalBP1) protein is highly conserved in mammals where it has been suggested to function as a molecular scaffold recruiting proteins involved in vesicular traffic and linking them to the actin cytoskeleton remodeling machinery. More recently POB1/REPS2 was found highly expressed in androgen-dependent prostate cancer cell lines, while one of its isoforms (isoform 2) is down regulated during prostate cancer progression.     

Solid-phase synthesis of 3-alkyl-2-arylamino-3,4-dihydroquinazolines

The solid-phase synthesis of 3-alkyl-2-arylamino-3,4-dihydroquinazolines using an N-Fmoc-β-amino-2-nitrobenzenepropanoic acid scaffold is described. The resin-bound scaffold was reductively alkylated with aldehydes or ketones after Fmoc deprotection, followed by reduction of the nitro group with tin(II) chloride. Subsequent cyclization of the 1,3-diamine intermediates with aryl isothiocyanates in the presence of 1,3-diisopropylcarbodiimide (DIC) afforded the desired products in high purity with moderate to good yield after trifluoroacetic acid (TFA) cleavage.     

Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole scaffold

A series of compounds possessing 2-(3-phenyl)ureidothiazol-4-formamide derivatives with a 2-ureidothiazole scaffold were designed and synthesized. Some compounds demonstrated inhibition of cell proliferation against both MDA-MB-231 and HepG2 cell lines using Sorafenib as the positive control. Compounds 6i showed a good to moderate inhibition on VEGFR-2 and PI3Kα which was proved by further molecular docking study. This study suggests that compound 6i is a potential dual inhibitor of VEGFR-2 and PI3Kα and is applicable for further investigation.     

Synthesis of alkyl 4-(diethoxymethyl)-3-pyridin-3-ylisoxazole-5-carboxylates: useful scaffold for highly functionalised 3-(pyridin-3-yl)isoxazoles

The methyl 4-(diethoxymethyl)-3-(pyridin-3-yl)isoxazole-5-carboxylate obtained by domino 1,3-dipolar cycloaddition and elimination starting of pyridine-3-nitrile oxide and methyl 4,4-diethoxy-3-p-tolylsulfinylbut-2-enoate is a convenient scaffold for the synthesis of other new highly functionalised 3-pyridin-3-ylisoxazoles-5-carboxylic acid derivatives and isoxazole-annulated heterocycles.     

A C3-symmetric molecular scaffold for the construction of large receptors

A novel C3-symmetric scaffold has been efficiently synthesized exhibiting the property that variable receptor arms can be easily attached by simple alkylation reactions; the utility of the scaffold as a skeleton for large receptors has been examined with a corresponding tris(bipyridyl) derivative toward phloroglucinol.     

Synthesis and reactions of 7-fluoro-4-methyl-6-nitro-2-oxo-2H-1-benzopyran-3-carboxylic acid: a novel scaffold for combinatorial synthesis of coumarins

7-Fluoro-4-methyl-6-nitro-2-oxo-2H-1-benzopyran-3-carboxylic acid has been prepared as a novel scaffold for combinatorial synthesis of coumarins. The scaffold has three points of diversity. The optimal conditions for its reactions with different nucleophiles in solid phase were obtained. Sixteen coumarin derivatives with different structures were designed and synthesized in solid phase to demonstrate its application as a scaffold for combinatorial synthesis of coumarins. Thirteen of these derivatives were obtained in high yields. Many of these model compounds fluoresce. Combinatorial libraries constructed with this novel scaffold may have interesting biological or physical properties.     

Synthesis and evaluation of potent, highly-selective, 3-aryl-piperazinone inhibitors of protein geranylgeranyltransferase-I

A series of compounds based on the carboxyl-terminal CAAL sequence of PGGTase-I substrates was designed and synthesized. Using piperazin-2-one as a semi-rigid scaffold, we have introduced critical pharmacophores in a well-defined arrangement to mimic the CAAL sequence. High potency and exceptional selectivity were obtained for inhibition of PGGTase-I with structures such as 45 and 70. Potency of this series of GGTIs was dependent on the presence of an L-leucine residue with a free carboxyl terminus, as well as an S configuration of the 3-aryl group. The selectivity was significantly enhanced by 5-methyl substitution on the imidazole ring and fluorine substitution on the 3-aryl group. Modification of the 6-position of the piperazinone scaffold was found to be unfavorable. Compounds 44 and 69, the corresponding methyl esters of 45 and 70, were found to selectively block processing of Rap1A by PGGTase-I in whole cells with IC(50) values of 0.4 microM and 0.7 microM respectively.     

Synthetic studies on 3-arylquinazolin-4-ones: intramolecular nucleophilic aromatic substitution reaction of 2-carboxamido-3-arylquinazolin-4-ones and its application to the synthesis of secondary aryl amines

The general synthesis and a novel intramolecular nucleophilic aromatic substitution (S_NAr) reaction of 2-carboxamido-3-arylquinazolin-4-ones, a potentially useful scaffold in the field of medicinal chemistry, are described. The synthetic utility of the S_NAr reaction as a tool for the synthesis of secondary aryl amines, including diaryl amines, is also demonstrated.     

Characterization of keratin–collagen 3D scaffold for biomedical applications

Fabrication of keratin–collagen (KC) 3D scaffold with improved thermal denaturation rate is reported. In vitro application of (KC) scaffold stimulates basic extra cellular matrix constituents. KC Scaffold considerably reduced undesirable properties of both collagen and keratin while collagen incorporation reduces the fragility with increases of strength and flexibility in the scaffold. In addition to this, the scaffold showed homogenous well‐interconnected pores in the range of 10–100 µm when observed in scanning electron microscope. Usage of keratin in KC scaffold offers increased biodegradation rate and higher denaturation rate in addition to its rapid cell growth with normal morphology ultimately reaching cell population of 3.9–9.7 million per cm³ after 48 hr in KC scaffold. Circular dichroism (CD) and Fourier transform spectroscopy (FT‐IR) of KC showed presence of helical structure of collagen and ß‐turns of keratin confirming retention of native structures of both the proteins KC scaffold showed good swelling behavior and water uptake. Our study strongly supports the superidity of KC scaffold over the collagen or keratin when they are independently used for tissue engineering applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Molecular recognition properties of FN3 monobodies that bind the Src SH3 domain

We have constructed a phage-displayed library based on the human fibronectin tenth type III domain (FN3) scaffold by randomizing residues in its FG and BC loops. Screening against the SH3 domain of human c-Src yielded six different clones. Five of these contained proline-rich sequences in their FG loop that resembled class I (i.e., +xxPxxP) peptide ligands for the Src SH3 domain. The sixth clone lacked the proline-rich sequence and showed particularly high binding specificity to the Src SH3 domain among various SH3 domains tested. Competitive binding, loop replacement, and NMR perturbation experiments were conducted to analyze the recognition properties of selected binders. The strongest binder was able to pull down full-length c-Src from murine fibroblast cell extracts, further demonstrating the potential of this scaffold for use as an antibody mimetic.     

Untersuchungen an Stickstoff-Jod-Verbindungen. X. Das Infrarotspektrum von Stickstofftrijodid-3-Ammoniak NJ3 · 3NH3 und Stickstofftrijodid-3-Deuteroammoniak NJ3 · 3ND3 im Bereich der N-J-Grundschwingungen

Studies on Nitrogen Iodine Compounds. X. The IR Spectra of NI₃ · 3NH₃ and NI₃ · 3ND₃ in the Region of N? I Fundamental Vibrations The IR spectra of NI₃ · 3 NH₃ and NI₃ · 3 ND₃ are similar to those of (NI₃ · NH₃)_n and (NI₃ · ND₃)_n, respectively. Especially the positions of the N? I vibrations are identical. From these results it is allowed to conclude that NI₃ · 3 NH₃ shows a N? I scaffold similar to the well known N? I scaffold of (NI₃ · NH₃)_n.     

Cell(MC3T3‐E1)‐Printed Poly(ϵ‐caprolactone)/Alginate Hybrid Scaffolds for Tissue Regeneration

A new cell‐printed scaffold consisting of poly(ϵ‐caprolactone) (PCL) and cell‐embedded alginate struts is designed. The PCL and alginate struts are stacked in an interdigitated pattern in successive layers to acquire a three‐dimensional (3D) shape. The hybrid scaffold exhibits a two‐phase structure consisting of cell (MC3T3‐E1)‐laden alginate struts able to support biological activity and PCL struts able to provide controllable mechanical support of the cell‐laden alginate struts. The hybrid scaffolds exhibit an impressive increase in tensile modulus and maximum strength compared to pure alginate scaffolds. Laden cells are homogeneously distributed throughout the alginate struts and the entire scaffold, resulting in cell viability of approximately 84%.     

Acrylic‐Acid‐Functionalized PolyHIPE Scaffolds for Use in 3D Cell Culture

This study describes the development of a functional porous polymer for use as a scaffold to support 3D hepatocyte culture. A high internal phase emulsion (HIPE) is prepared containing the monomers styrene (STY), divinylbenzene (DVB), and 2‐ethylhexyl acrylate (EHA) in the external oil phase and the monomer acrylic acid (Aa) in the internal aqueous phase. Upon thermal polymerization with azobisisobutyronitrile (AIBN), the resulting porous polymer (polyHIPE) is found to have an open‐cell morphology and a porosity of 89%, both suitable characteristics for 3D cell scaffold applications. X‐ray photo­electron spectroscopy reveals that the polyHIPE surface contained 7.5% carboxylic acid functionality, providing a useful substrate for subsequent surface modifications and bio‐conjugations. Initial bio‐compatibility assessments with human hepatocytes show that the acid functionality does not have any detrimental effect on cell adhesion. It is therefore believed that this material can be a useful precursor scaffold towards 3D substrates that offer tailored surface functionality for enhanced cell adhesion.

     

The Design,Synthesis, and Evaluation of 1,5,7‐Trisubstituted‐3‐Pyridyl‐Xanthones for Use as Insecticides Starting from Pyripyropene A

A readily accessible template of 1,5,7‐trisubstituted‐3‐pyridyl‐xanthones was designed starting from naturally occurring pyripyropene A for agrichemical development. Our originally developed Ag₂CO₃‐mediated oxidative cyclization enabled ready access to the key scaffold, 1,5,7‐trihydroxy‐3‐chloro‐xanthone. The chemo‐ and regioselective sequential introduction of four substituents to the scaffold rapidly afforded the desired, structurally diverse 1,5,7‐trisubstituted‐3‐pyridyl‐xanthones. An evaluation of insecticidal activity revealed that one of the synthesized compounds retained insecticidal activity against vetch aphid and green peach aphid. The observed insecticidal spectrum was similar to that of pyripyropene A. The developed template could be a valuable aid for future agrichemical development.     

Improved synthesis of the valuable peptidomimetic intermediate 3-azido-4-hydroxy cyclopentanoic acid

An improved synthesis of 3-azido-4-hydroxy cyclopentanoic acid 2 is presented. This molecule is useful as a synthetic scaffold for β-turn mimetics on solid phase, with the selectivity of the turns being dependent on the diastereomer employed. A high diastereoselectivity in the synthesis of this molecule in solution is reported, which may then be attached to the solid phase for the synthesis of peptidomimetic libraries.     

Visible-light-promoted gas-phase water splitting using porous WO3/BiVO4 photoanodes

We recently described the use of Ti(0) microfibers as an anodization substrate for the preparation of TiO₂ nanotubes arrays as porous photoanodes. Here, we report the use of these fibers as a scaffold to build porous photoanodes based on a WO₃/BiVO₄ heterojunction. The obtained photoelectrodes show promising results under visible light irradiation for water oxidation both in a typical liquid-phase photoelectrochemical setup and in a gas phase reactor (developed in-house) based on a polymeric electrolyte membrane.     

丝素蛋白修饰改性的聚羟基脂肪酸酯支架上人体平滑肌细胞的生长

聚三羟基丁酸脂和聚三羟基己酸脂的共聚物(PHBHH_x)是一种具有良好强度和韧性的生物可降解高分子材料, 可作为组织工程心脏瓣膜支架的选择材料之一. 但其生物相容性尚不甚理想. 为此, 本工作利用丝素蛋白修饰改性高分子多孔支架, 以提高支架的生物相容性. 并将人体平滑肌细胞接种在该复合支架上进行体外培养, 以证实改性效果. 其中, 用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)方法测试细胞生长, 评估复合支架的细胞相容性. 并用扫描电子显微镜观察细胞在支架上的生长形态. 结果显示, 丝素蛋白修饰改性后的复合支架更有利于细胞的粘附与生长, 平滑肌细胞在支架上表现出良好的生长形态. 这表明, 丝素能够改善多孔支架的生物相容性, 使PHBHH_x/丝素蛋白复合物能更适宜作为组织工程心脏瓣膜的支架材料. 结果对于进一步研究细胞外间质在复合支架上的生长以及体外培养的组织重建有重要的参考意义.