纳米银/植物源复合抗菌剂的制备及其抑菌性能的研究

以硝酸银作为银源,水溶性淀粉作保护剂,丙酮酸钠作还原剂,氨水提供碱性环境来制备纳米银胶,并以聚乙烯吡咯烷酮(PVP)作分散稳定剂,复配红景天提取液和无患子提取液制备出纳米银/植物源复合抗菌剂。实验结果表明,纳米银胶或植物提取液仅对部分细菌或霉菌有较强抑制效果,而复合抗菌剂对细菌、霉菌均有很强抑制效果。在湿巾液中添加0.5%复合抗菌剂时,其对大肠杆菌,金黄色葡萄球菌和白色念珠菌的抗菌效率可达99%,且经过常温六个月、高温55℃一个月保存后,其抗菌活性分别可达到95%、90%左右,表明复合抗菌剂具有较强的抗菌效率及抗菌稳定性。     

β-环糊精主客体识别抗菌剂及抗菌性能研究进展

细菌污染与人类的生存息息相关,随着多重耐药细菌的增加,提高抗菌剂抗菌性能、抑制细菌传播和感染成为抗菌剂研究领域的热点问题。利用β-环糊精的包结作用与抗菌剂主客体识别改善抗菌剂的理化性质,增强抗菌剂的抗菌性能引起了广泛关注。环糊精具有内疏水外亲水的特殊结构,疏水内腔可选择性地与空腔大小相匹配的疏水客体分子进行主客体识别,将抗菌剂包合,从而改善抗菌剂理化性质,提高抗菌剂抗菌性能。本文综述了β-环糊精及其衍生物与有机抗菌剂、天然抗菌剂主客体识别对抗菌剂理化性质及抗菌性能的影响,分析了主客体识别的包合机理及主客体之间的作用,系统地归纳总结了环糊精主客体识别抗菌剂对不同细菌的抗菌作用及在医药、纺织、食品等领域的应用研究现状,以期为环糊精主客体识别抗菌剂的深入研究及应用提供参考。     

一株病原拮抗野生菌株的筛选、鉴定及其发酵工艺优化

为获得广谱抗菌功能野生菌株并提高其发酵产物中抗菌物质的含量。采用管碟法和菌丝生长速率法筛选功能菌株,ITS序列分析鉴定功能菌株,通过响应面法和正交设计优化发酵生产抗菌物质的工艺。筛选到一株强效、广谱抗菌功能菌株,鉴定为Cerrena sp.,其发酵产物对金黄色葡萄球菌、大肠杆菌、白色念珠菌、枯草芽孢杆菌和水稻纹枯病菌有显著拮抗作用。该菌株的摇甁发酵配方及培养条件为：马铃薯13.99 g/L,蔗糖 41.58 g/L,VB1 0.027 g/L,麸皮7 g/L,KH₂PO₄ 2 g/L,MgSO₄·7H₂O 2 g/L;摇床温度28 ℃、发酵周期10 d、种龄4 d、接种量8%、初始pH为5.0、装液量110 ml/250 ml。该菌株有明显抑菌活性,发酵工艺优化后抗菌活性提高了30.37%,为该菌株今后的应用、抗菌剂的分离提纯和产业化提供了实验依据。     

纳米抗菌剂抗菌性能研究进展

纳米抗菌剂是新型高效的抗菌材料,使用安全、方便,稳定性好,抗菌谱广,抗菌效力强,已逐步应用于纺织、建筑、医疗等行业。我们分析了近几年对抗菌纳米粒子及其复合物的实验研究,简要综述纳米抗菌剂抗菌活性的研究成果,展望纳米抗菌剂发展的主要趋势,为制备更直接有效的纳米抗菌剂提供理论基础和实验研究依据。     

纳米银/碳质球复合抗菌材料的制备及其抗菌性能研究

本文研究了纳米银/碳质球复合抗菌材料的制备及其形貌与结构,以大肠杆菌为代表菌株,研究了复合抗菌材料的抗菌活性,获得了抗菌性能良好的复合抗菌材料,所制备的抗菌材料有望在有害微生物防治方面获得广泛应用。     

纳米酶的抗菌作用及其机制研究进展

抗生素类药物的发现和使用给人类提供了抗击细菌感染的强大武器。但是,抗生素长期使用导致的细菌耐药问题限制了其在临床上的应用。开发新型的基于纳米酶(Nano-Enzyme)的新型抗菌剂为解决上述问题提供了新思路。将纳米酶可以归为两大类:一类是酶和纳米材料的复合材料;另一类是纳米材料本身具有类酶活性。因为银(Ag)纳米粒子是历史最悠久且研究最广泛的纳米抗菌剂,而且其抗菌机制多样化,因此将Ag纳米粒子的抗菌机制和最新进展单独论述。纳米抗菌剂可以组合多种抗菌机制协同抗菌,从而提高其抗菌性能。因此,在这篇综述中系统介绍了Ag纳米粒子和上述2种类型纳米抗菌剂的最新研究进展和抗菌机制,重点介绍了纳米材料的物理性质对抗菌活性和生物安全性的影响。最后,该综述还强调了该领域目前面临的问题和挑战,并对该领域的发展前景进行了展望。     

等离子体-紫外复合诱变选育四羟基环孢菌素衍生物高产菌株

筛选可体内转化合成环孢菌素衍生物([γ-HyMeLeu4]CyA)的高产菌株。以稀有放线菌Nonomuraea dietziae为出发菌株,采用常温常压等离子体射流和紫外照射对其进行复合物理诱变。通过该诱变方法获得了具有稳定遗传性能的菌株,其转化效率比出发菌株提高了32%左右。结果表明,等离子体诱变可有效的用于该稀有放线菌,通过等离子体-紫外复合诱变筛选得到的突变菌株可用于工业生产。     

不同虫花棒束孢菌株固体培养提取物抗氧化和抗菌活性初步测定

虫花棒束孢(Isaria farinosa)是一种常见的土栖昆虫病原真菌,在害虫生物防治方面有着广泛研究和应用,其对人体保健、药效和活性成分等方面也有一定的研究。为了揭示不同菌株之间的差异,选择7个来源不同的菌株,经形态和分子鉴定后,通过大米固体培养和乙酸乙酯提取,进行了抗氧化和抗菌活性测定。研究结果表明不同来源的虫花棒束孢菌株,经相同条件的培养和提取得到的产物在抗氧化和抗菌活性方面呈现明显的差异,以菌株2142表现最佳,在抗菌实验中尤其突出。菌株2142乙酸乙酯粗提物(200 mg/m L)对蜡样芽胞杆菌的抗菌活性达到与阳性对照氨苄西林钠(80μg/m L)相似的水平。该菌株具有较好的应用前景,有待进一步深入研究。利用虫花棒束孢菌株研发保健产品或医药产品具有很好的潜力,但其菌株来源需要十分关注;筛选对人体安全可靠,并有利于产品开发利用的优良菌株是一项非常重要的工作。     

一株盐湖芽孢杆菌LG的鉴定及其抗金黄色葡萄球菌活性研究

【目的】从运城盐湖中分离获得一株耐盐细菌LG,对其进行分类鉴定及抗菌特性研究。【方法】利用16S rRNA基因序列分析对菌株进行分类鉴定。以金黄色葡萄球菌为指示菌,采用杯碟法对菌株LG发酵上清液进行抗菌活性检测,利用扫描电镜和透射电镜观察其抗菌效果。研究不同因素对上清液抗菌活性的影响,并采用PCR技术对菌株基因组进行功能基因筛查。【结果】系统发育分析表明该菌为Bacillus属成员,在0–25%的NaCl浓度范围内生长良好,为耐盐细菌。电镜观察发现,菌株LG发酵上清液处理金黄色葡萄球菌可导致细胞结构明显出现异常,细胞质泄漏。抗菌稳定性研究表明,菌株LG发酵上清液活性稳定,表现出了良好的对紫外光、温度、pH和NaCl的耐受性。采用特异性引物,通过PCR筛查发现菌株LG基因组中含有聚酮合酶(PKS I)基因和非核糖体肽合成酶(NRPS)基因,表明该菌具有产多种代谢产物的潜力。【结论】极端环境中的微生物资源可作为抗菌活性物质的潜在新来源。     

海带藻际微生物抗菌活性及其多样性的初步研究

从浙江台州海域健康海带、病烂海带(Laminaria japonica)及其周围海水中分离纯化海带藻际微生物, 利用双层琼脂扩散法对获得的菌株进行抗菌活性筛选, 比较活性菌株与来源的相关性, 并对具有抗菌活性的菌株进行16S rRNA系统发生学分析。结果显示, 在分离的143株海带藻际微生物中, 有42株细菌具有抗菌活性, 其中来源于健康海带和海水的活性菌株比例(35%和29%)大于来源于病烂海带的细菌(23%)。对其中16株具有广谱抗菌活性的菌株进行的16S rRNA系统发生学分析显示, 分别属于Pseudoalteromonas、Rahnella、Donghaeana、Bacillus和Exiguobacterium 5个属。为从藻际微环境的微生物多样性入手了解海带病烂机制以及寻找新的抗菌药物提供研究材料。       

对萘磺酸钠修饰的石墨烯基纳米银复合抗菌材料的制备及性能评价

制备采用1-萘磺酸钠修饰的石墨烯基纳米银复合材料,并对其性能进行评价。首先制备了石墨烯基纳米银复合材料,采用1-萘磺酸钠修饰,记为AgNP/rGO-NA,然后通过与聚乙烯吡咯烷酮做保护剂的纳米银（PVP/AgNP）的比较,分析其稳定性,抗菌活性,细胞毒性。研究发现,纳米银AgNP在制备的复合材料表面的分布相对均匀,AgNP的质量分数为4.3%,粒径为5~15nm,Zeta电位为-42.5 mV;在无光或光照强度为3000 Lx（勒克斯）的低温光照仪环境下储存10 d,PVP/AgNP聚集作用较为明显,而AgNP/rGO-NA则分散性良好,聚集作用不明显;AgNP/rGO-NA具有更加良好的抗菌活性,生物相容性和相对较低的生物毒性。试验表明经过1-萘磺酸钠修饰的石墨烯基纳米银复合材料质量可靠,性能良好,具有广阔的应用前景。     

硅纳米针阵列抗菌材料的制备及其抗菌性能研究

本文以简易经济的金属辅助化学刻蚀技术制备了具有高效杀菌性能的硅纳米抗菌材料并研究其形貌与结构,以大肠杆菌和金黄色葡萄球菌为代表菌株,研究了纳米针抗菌材料的抗菌活性。实验证明,该抗菌材料对在其表面培养3 h的大肠杆菌和金黄色葡萄球菌的杀菌效率分别为85.12%,76.40%,表明该材料对革兰氏阳性和革兰氏阴性菌均有高的杀菌效果,所制备的抗菌材料有望为医疗卫生系统在抵抗细菌污染方面提供解决方案。     

Nanoparticles functionalized with ampicillin destroy multiple-antibiotic-resistant isolates of Pseudomonas aeruginosa and Enterobacter aerogenes and methicillin-resistant Staphylococcus aureus

We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nanoparticles (AuNP) were antimicrobial only when ampicillin was bound to their surfaces. Both AuNP and AgNP functionalized with ampicillin were effective broad-spectrum bactericides against Gram-negative and Gram-positive bacteria. Most importantly, when AuNP and AgNP were functionalized with ampicillin they became potent bactericidal agents with unique properties that subverted antibiotic resistance mechanisms of multiple-drug-resistant bacteria.     

Extracellular biosynthesis of silver nanoparticles using a novel and non-pathogenic fungus,Neurospora intermedia: controlled synthesis and antibacterial activity

In the present study, the biosynthesis of silver nanoparticles (AgNPs) using Neurospora intermedia, as a new non-pathogenic fungus was investigated. For determination of biomass harvesting time, the effect of fungal incubation period on nanoparticle formation was investigated using UV–visible spectroscopy. Then, AgNPs were synthesized using both culture supernatant and cell-free filtrate of the fungus. Two different volume ratios (1:100 and 1:1) of the culture supernatant to the silver nitrate were employed for AgNP synthesis. In addition, cell-free filtrate and silver nitrate were mixed in presence and absence of light. Smallest average size and highest productivity were obtained when using equal volumes of the culture supernatant and silver nitrate solution as confirmed by UV–visible spectra of colloidal AgNPs. Comparing the UV–visible spectra revealed that using cell-free filtrate for AgNP synthesis resulted in the formation of particles with higher stability and monodispersity than using culture supernatant. The absence of light in cell-free filtrate mediated synthesis led to the formation of nanoparticles with the lowest rate and the highest monodispersity. The presence of elemental silver in all prepared samples was confirmed using EDX, while the crystalline nature of synthesized particles was verified by XRD. FTIR results showed the presence of functional groups which reduce Ag⁺ and stabilize AgNPs. The presence of nitrate reductase was confirmed in the cell-free filtrate of the fungus suggesting the potential role of this enzyme in AgNP synthesis. Synthesized particles showed significant antibacterial activity against E. coli as confirmed by examining the growth curve of bacterial cells exposed to AgNPs.     

Rapid synthesis of antimicrobial paper under microwave irradiation

The silver-nanoparticle (AgNP) containing paper was successfully prepared. The AgNP is deposited by the in situ reduction of silver nitrate on the acrylamide grafted bagasse paper sheets in the presence of citrate molecules as stabilizing agent. In the present paper, grafting of acrylamide onto bagasse paper sheets using potassium persulfate was carried out under the influence of microwave radiations (MWR). The modified paper sheets were characterized by Fourier transform infrared spectroscopy (FTIR), UV-spectroscopy, and scanning electron microscopy (SEM). Antimicrobial activities of the prepared paper sheets were also investigated against G+ve bacterium Staphylococcus aureus, G-ve bacterium Pseudomomas aeruginosa, and yeast Candida albicans, which are model microorganisms for testing bactericidal properties. The AgNP containing paper sheets exhibited antibacterial activity.     

Synthesis,characterization, and antibacterial properties of silver nanoparticles-graphene and graphene oxide composites

In the field of nanotechnology, silver nanoparticles have been considered a promising antibacterial material for a century. The potential applications of graphene-based materials are increasingly recognized for their special physico-chemical and biological properties. In particular, graphene and graphene oxide as the foundation of nanocomposites have garnered much interest among researchers in many fields. In this review, we concentrate on different aspects of silver nanoparticle composites with graphene and graphene oxide, focusing on their synthesis methods, special characteristics, and antibacterial properties; we also briefly discuss limitations and future research.     

Synthesis and antibacterial evaluation of a series of oligorhamnoside derivatives

A series of novel oligorhamnoside derivatives (1–10) and naturally occurring cleistrioside-5 were synthesized and evaluated for their in vitro antibacterial activities. Among them, dirhamnoside derivative 7 and cleistrioside-5 displayed similar antibacterial profiles and exhibited moderate to good inhibitory activities on bacterial growth against a panel of Gram-positive bacteria (MICs ? 4–32 μg/mL). The results revealed that these two compounds showed selectivity towards bacterial species strictly, without being affected by the antibiotic-resistant/susceptible properties of one species, which suggested that they might have the potential to avoid antibiotic cross-resistance. In addition, the preliminary SARs of this type of oligorhamnoside derivatives on the antibacterial activities were determined.     

Physical, mechanical, and antibacterial properties of chitosan/PEO blend films

Films formed by blending of two polymers usually have modified physical and mechanical properties compared to films made of the individual components. Our preliminary studies indicated that incorporation of chitosan in polyethylene oxide (PEO) films may provide additional functionality to the PEO films and may decrease their tendency to spherulitic crystallization. The objective of this study was to determine the correlation between chitosan/PEO weight ratio and the physical, mechanical, and antibacterial properties of corresponding films. Films with chitosan/PEO weight ratios from 100/0 to 50/50 in 10% increments were characterized by measuring thickness, puncture strength (PS), tensile strength (TS), elongation at break (%E), water vapor permeability (WVP), and water solubility (WS). Additionally, the films were examined by polarized microscopy, wide-angle X-ray diffraction (WAXD), and Fourier transform infrared (FTIR) spectroscopy, and their antibacterial properties were tested against Escherichia coli. The chitosan fraction contributes to antimicrobial effect of the films, decreases tendency to spherulitic crystallization of PEO, and enhances puncture and tensile strength of the films, while addition of the PEO results in thinner films with lower water vapor permeability. Films with 90/10 blend ratio of chitosan/PEO showed the most satisfactory PS, TS, %E, and antibacterial properties of all tested ratios.     

掺银二氧化钛空心球的制备及其抗菌性能研究

以硫酸钛、尿素为原料,碳球为模板,采用水热沉淀法制备了二氧化钛空心球,以聚乙烯吡咯烷酮(PVP)为分散剂、硼氢化钾还原硝酸银的方法得到银掺杂的二氧化钛空心球。采用X射线粉末衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、能谱仪(EDS)和傅里叶变换红外光谱仪(FT-IR)等测试手段对所得的样品进行了表征。采用抑菌圈法对其抗菌性能进行了检测,实验结果表明,在自然光条件下,商品二氧化钛P25和二氧化钛空心球对大肠杆菌、金黄色葡萄球菌、白色念珠菌没有任何抗菌效果,而载银量9.4 mol%的二氧化钛在常温范围内对三个菌种都具有优良的抗菌性能,可用于抗菌塑料、抗菌食品包装和抗菌纺织制品等领域。     

The antibacterial properties of secreted phospholipases A(2)

There is a considerable body of evidence to support the antibacterial properties of the group IIa phospholipase A(2) as an important physiological function. This enzyme is able to act as an acute phase protein and may be part of the innate defence system of the body, acting in concert with other antibacterial proteins and peptides. The enzyme is most effective against Gram-positive bacteria whereas penetration of the lipopolysaccharide coat of Gram-negative bacteria requires bactericidal/permeability-increasing protein (BPI) as an additional permeabilizing factor. The global cationic nature of this protein (pI>10.5) appears to facilitate penetration of the anionic bacterial cell wall. In addition, the considerable preference of the enzyme for anionic phospholipid interfaces provides specificity toward anionic bacterial membranes as opposed to zwitterionic eucaryotic cell membranes.