Fabrication and Excellent Antibacterial Activity of Well-defined CuO/Graphdiyne Nanostructure

Copper oxide(CuO),due to its low cost,good chemical and physical stability,has recently been given special attention as a potential candidate for antibacterial agents.However,developing novel CuO nanocomposites with improved antibacterial property and unraveling the interface promotion mechanism has been a fundamental challenge for decades.Herein,well-defined CuO/graphdiyne(CuO/GDY)nanostructures with uniformly anchored CuO nanoparticles(ca.4.5 nm)have been fabricated.The CuO/GDY nanostructure exhibited superior E.coli inactivation efficiency,which is nearly 19 times and 7.9 times higher than the bare GDY and commercial CuO,respectively.The improved E.coli inactivation performance was mainly due to the increased reactive O2-species generated by the activation of molecular O2 over CuO/GDY surface.These findings demonstrate the efficient antibacterial activity of well-defined CuO/GDY nanostructures and provide insights on the development of efficient GDY-based antibacterial materials.     

Silver(I)‐N‐heterocyclic carbene complexes of bis‐imidazol‐2‐ylidenes having different aromatic‐spacers: synthesis,crystal structure,and in vitro antimicrobial and anticancer studies

A series of Ag(I) complexes ( 6 , 7 , 8 , 9 ) derived from imidazol‐2‐ylidenes was synthesized by reacting Ag₂O with an o‐, m‐, p‐xylyl or 1,3,5‐triazine‐linked imidazolium salts ( 1 , 2 , 3 , 4 ) and then characterizing these using various spectro‐analytical techniques. Additionally, triazine‐linked bis‐imidazolium salt 5 was characterized using the single‐crystal X‐ray diffraction method. Complexes 6–9 were formed from the N‐heterocyclic carbene ligand precursors 1–3 as PF₆^‐ salts in good yields. Conversely, salt 5 does not form Ag(I) complex even under various reaction conditions. Using ampicillin as a standard, complexes 6–9 were tested against bacteria strains Escherichia coli and Staphylococcus aureus as Gram‐negative and Gram‐positive bacteria, respectively, showing potent antimicrobial activities against the tested bacteria even at minimum inhibition concentration and bacterial concentration levels. Furthermore, the potential anticancer activities of the reported complexes were evaluated against the human colorectal cancer (HCT 116) cell lines, using 5‐fluorouracil as a standard drug. The highest anticancer activities were observed for complex 8 with an IC₅₀ value of 3.4 μm , whereas the lowest was observed for complex 9 with an IC₅₀ value of 18.1 μm . Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis by Emulsion Polymerization of Poly(butyl acrylate-co-silver acrylate) Ionomers and Evaluation of their Possible Applications

The synthesis by emulsion polymerization and the characterization by a battery of techniques of poly(butyl acrylate-co-silver acrylate) [poly(BuAc-co-AgAc)] ionomers are reported here. Reaction rates were fast and conversions around 90% were obtained in less than one hour, regardless of the initial ratio of butyl acrylate and silver acrylate employed (BuAc/AgAc = 90/10, 80/20, 70/30). Particle size was in the range of 176 to 200 nm, depending on the BuAc/AgAc ratio. Ionomers’ formation was corroborated by infrared spectroscopy and inferred by differential scanning calorimetry (DSC). DSC disclosed that the poly(BuAc-co-AgAc) has two glass transition temperatures: one at ca. ?49°C due to relaxation of the ionomer backbone domains rich in BuAc and another ca. 35°C due to the relaxation of the backbone domains where the AgAc-units content was higher. Young moduli increased as the copolymers became richer in AgAc. Antibacterial tests against Escherichia coli with the 90/10 (BuAc/AgAc) ionomer revealed that the bacteria population diminishes from 5 log CFU/mL to less than 0.3 MPN/mL after one hour of contact with the ionomers. Also, we demonstrated that the ionomers are excellent compatibilizers for making semiconductive films of n-dodecylbenzene sulfonic acid-doped polyaniline (PANIDBSA)-poly(BuAc-co-AgAc) and poly(n-butyl methacrylate) (PBMA) blends. The electrical conductivity of the blend films, which were homogeneous, rose as the AgAc content in the films increased.     

细胞内蛋白质磁共振

细胞内的环境异常复杂，其中生物大分子的浓度超过300 mg/mL并占据着大约30%的细胞内空间. 然而，直到目前为止大多数的蛋白质研究仍然在细胞外或是甚至非常稀的缓冲液中进行. 细胞内磁共振（In-cell NMR）提供了一个可以直接非损伤地获取细胞内原子水平信息的方法. 虽然In-cell NMR在近10年里有了较大的发展，但是这一技术尚未成熟. 在该篇综述中，作者首先总结制约这一技术发展的因素以及研究中需要注意的事项，最后讨论了未来的发展方向.     

Coumarin‐tethered (benz)imidazolium salts and their silver(I) N‐heterocyclic carbene complexes: Synthesis,characterization, crystal structure and antibacterial studies

A series of new sterically modulated chlorocoumarin‐substituted (benz)imidazolium salts and their bis‐N‐heterocyclic carbene silver(I) complexes were prepared and characterized. The complexes were prepared in good yields following the in situ deprotonation method by treating azolium salts with silver(I) oxide in the dark. All the compounds were characterized using various spectroscopic and analytical methods. Additionally, one of the benzimidazolium salts was characterized using single‐crystal X‐ray diffraction technique. In this salt, intermolecular π–π stacking interactions operate between benzimidazole as well as coumarin heterocyclic systems with adjacent molecules. In the preliminary antibacterial studies, the silver complexes were found more active than the corresponding salts against a panel of bacterial strains. Interestingly, the complexes displayed improved antibacterial efficacy against Escherichia coli strain, comparable with that of the standard drug ampicillin.     

Non-symmetrically p-nitrobenzyl- and p-cyanobenzyl-substituted N-heterocyclic carbene-silver(I) complexes: synthesis,characterization and antibacterial studies

Various nitro/nitrile-functionalized benzimidazol-2-ylidene carbene complexes of silver(I) (7a–d and 11a–d) were synthesized by combination of 1-allyl/1-isopropyl/1-sec-butyl/1-isopentyl-3-(nitro/cyano-benzyl)-3H-benzimidazol-1-ium hexafluorophosphate (6a–d and 10a–d) with silver(I) oxide in acetonitrile. The compounds were characterized by ¹H, ¹³C NMR, FT-IR, mass spectrometry, and elemental analysis. Additionally, the in vitro antibacterial activity of the N-heterocyclic carbene (NHC) precursors (6a–d and 10a–d) and their corresponding NHC-silver(I) complexes (7a–d and 11a–d) were investigated against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli using the qualitative Kirby-Bauer disk diffusion method. All the NHC-silver(I) complexes exhibited medium-to-high antibacterial activity with areas of clearance ranging from 12 mm to 21 mm, while the NHC precursors were inactive against both strains of bacteria.     

纳米金标记抗体增强SPR检测大肠杆菌O157∶H7

将金纳米粒子(AuNPs)标记的大肠杆菌O157∶H7(E.coli O157∶H7)的多克隆抗体(PAb)作为二抗,采用氨基偶联法将PAb固定在传感器表面作为一抗,通过三明治方法用双通道表面等离子体子共振(SPR)传感器对E.coli O157∶H7进行检测,并与SPR直接法检测进行了比较.结果表明,直接法的检出限为103cfu/mL,线性范围为103～109cfu/mL;AuNPs增强三明治法的检出限为10 cfu/mL,线性范围为10～1010cfu/mL,灵敏度比直接法提高了100倍,且具有更宽的检测范围.本方法不仅检测时间短,而且具有良好的选择性和重现性.     

MVF Sensor Enables Analysis of Nucleic Acids with Stable Secondary Structures

One major challenge in nucleic acids analysis by hybridization probes is a compromise between the probe's tight binding and sequence‐selective recognition of nucleic acid targets folded into stable secondary structures. We have been developing a four‐way junction (4WJ)‐based sensor that consists of a universal stem‐loop (USL) probe immobilized on an electrode surface and two adaptor strands (M and F). The sensor was shown to be highly selective towards single base mismatches at room temperature, able to detect multiple targets using the same USL probe, and have improved ability to detect folded nucleic acids. However, some nucleic acid targets, including natural RNA, are folded into very stable secondary and tertiary structures, which may represent a challenge even for the 4WJ sensors. This work describes a new sensor, named MVF since it uses three probe stands M, V and F, which further improves the performance of 4WJ sensors with folded targets. The MVF sensor interrogating a 16S rRNA NASBA amplicon with calculated folding energy of ?32.82 kcal/mol has demonstrated 2.5‐fold improvement in a signal‐to‐background ratio in comparison with a 4WJ sensor lacking strand V. The proposed design can be used as a general strategy in the analysis of folded nucleic acids including natural RNA.     

Calixarene coated gold nanoparticles as a novel therapeutic agent

In the current study, gold nanoparticles (AuC6NPs and AuC8NPs) were prepared through sodium borohydride reduction method by using Calix[6]rene and Calix[8]rene as a stabilizing agents. The synthesized AuNPs were screened for cytotoxic, phytotoxic, antifungal and antibacterial activities. The fabricated AuNPs were characterized by UV–visible spectroscopy, atomic force microscopy (AFM) and FTIR spectroscopy. Antibacterial activities of the AuNPs were tested against E. coli and S. aureus. The AuC6NPs were found to be effective against the growth of gram positive bacteria and inhibited the growth of S. aureus. AuC6NPs interact with bacterial cell and damaged cell membrane. Roughness of the bacterial surface and membrane rupture can be clearly observed by AFM images. The AuNPs possess insignificant antifungal activity against Aspergillus niger and Candida albicans. Moreover, AuC8NPs have significant phytotoxicity and moderate cytotoxicity.     

DNA microarray: a high throughput approach for methylation detection

We described a DNA microarray-based method combined with bisulphite treatment of DNA and regular PCR to examine hyper-methylation in promoter 1A of APC gene. A set of oligonucleotide probes were designed and immobilized on the aldehyde-coated glass slides for detecting the methylation pattern of 15 selected CpG sites in the region. The methylation status of 30 colorectal tumor samples have been examined by both of methylation-specific PCR (MS-PCR) and the present microarray method. The methylation pattern of the 15 CpG sites for the samples have been obtained with the microarray. A total of 19 samples out of 30 were methylated by microarray, in which five samples cannot be detected by MS-PCR due to the methylated CpG patterns not accordant to the MS-PCR primers. The detecting ratio for methylation of APC gene of colorectal tumor samples increased from 46.7% with MS-PCR to 63.3% with the microarray, which successfully demonstrated that DNA microarray-based method not only can obtained the methylation patterns for the related genes, but also decrease the false-negative results of methylation status by the conventional MS-PCR for the investigated genes.