共查询到19条相似文献，搜索用时 46 毫秒
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采用介观动力学(MesoDyn)模拟方法研究了聚乙二醇(PEG)与十二烷基羟丙基磺基甜菜碱(DSB)在水溶液中的聚集行为,从介观层次上探讨了PEG以及与DSB混合体系的聚集过程和聚集形态,并对混合体系中DSB的体积分数、温度和剪切速率等影响因素进行了分析。实验结果表明,PEG在水溶液中随体积分数增加会形成球形、棒状、蠕虫状聚集体和网状结构;PEG与表面活性剂DSB之间存在着较强的协同作用,在较低的DSB体积分数下PEG即可产生聚集现象;随着温度的增加,PEG/DSB混合体系聚集变得较为困难,而且聚集的速度也逐渐变慢,说明整个聚集过程是放热的;并且剪切作用对体系聚集行为影响较大。 相似文献
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磺基甜菜碱分子结构中具有强酸根基团,是典型阴离子性和阳离子性极性集于一身季胺内盐型两性表面活性剂。磺基甜菜碱具有耐酸碱、钙皂分散性强、毒性低,化学稳定性好等优点;因而日益受到人们的重视,在日用化工及其它行业中的应用前景看好。本文主要介绍一种新型表面活性剂—双十四烷基双磺基甜菜碱的合成工艺条件。考察反应时间、温度等工艺条件对反应产物收率的影响。并通过红外光谱图验证了产物结构。通过优化工艺条件,在125℃反应16h甜菜碱的收率达到95.8%。 相似文献
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为了研究非-两性离子混合型表面活性剂的构效关系,以乙氧基(EO)长度n分别为1,2,3和4的N,N-二甲基-N-十二烷基聚氧乙烯醚磺基甜菜碱(C_(12)EO_nSBe)为研究对象,利用滴体积法、时间分辨荧光法等获得C_(12)EO_nSBe的临界胶束浓度(cmc)、胶束聚集数(Nm)等性质参数。实验结果表明:与分子结构相近的传统十二烷基磺基甜菜碱(C_(12)SBe)相比,C_(12)EO_nSBe的cmc更低;随着n增大,C_(12)EO_nSBe的cmc降低,饱和吸附量(Γ_m)增大,分子占据面积(A_(min))减小,临界胶束聚集数(N_(m,c))减小。 相似文献
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研究了N-十二烷基-N,N-二甲基-N-苄磺基甜菜碱(DBSB)作为代磷助剂的性能。结果表明,DBSB的钙皂分散指数为3%,与十二烷基苯磺酸钠(LAS)二元复配后,可提高复配体系的钙离子稳定性,当DBSB占二元体系的质量分数为15%时,体系承受的钙离子浓度从5 mmol·L-1升高到30 mmol·L-1。以DBSB替代4A沸石加入到无磷模拟洗衣粉配方中,可保持较好的去污力,且DBSB的加入可大幅度提高配方的抗硬水性能。通过正交试验得到优化配方5,其在250和400 mg·L-1硬水中的去污力均优于4A沸石无磷模拟配方(配方6),且灰分残留量较少,具有低泡性,pH、总活性物含量及游离碱含量符合国标要求。 相似文献
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以十二烷基二甲基苄基氯化铵为原料,经磺化合成了一种磺基位于芳香环上的两性离子型表面活性剂——N-十二烷基-N,N-二甲基苄磺基甜菜碱(SBAS),用ESI-MS和1HNMR表征了其结构。同时,考察了SBAS分别与十二烷基苯磺酸钠(LAS)或脂肪酸钠皂的复配性能。实验结果表明,在保持去污效果的前提下,SBAS能显著提高LAS和脂肪酸钠皂的抗硬水能力。因此,SBAS有望用于无磷洗涤剂或复合皂配方中作为高效抗硬水助剂。 相似文献
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以3-氯-2-羟基丙磺酸钠与n-十二烷基咪唑为原料,合成了两性型离子液体(IL)表面活性剂1-(2-羟丙基磺基)-3-十二烷基咪唑内盐(HPSDim),通过ESI-MS,FTIR及1HNMR表征其分子结构;分别用表面张力法和稳态荧光法测定了35℃时HPSDim在0.5 mol·L-1的NaCl水溶液中的临界胶束浓度(cmc)和平均胶束聚集数(Nm)等表面活性参数。结果表明,HPSDim的Krafft点高达(65.8±0.5)℃,但在室温下易溶于0.5 mol·L-1的NaCl水溶液中;表面张力法测得其cmc为0.98 mmol.L-1(荧光探针法为1.0 mmol·L-1);在6.0～8.0 mmol·L-1范围内,Nm随HPSDim浓度增加而线性增大,推算其临界胶束聚集数(Nm,c)为30.9;其堆积参数(Pc)为0.40,推测HPSDim胶束形状可能为柱状。 相似文献
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Andrej Minich Zdenko Levarski Mria Mikul&#x;ov Marek Straka Adrina Liptkov Stanislav Stuchlík 《International journal of molecular sciences》2022,23(3)
The presence of Staphylococcus epidermidis biofilms on medical devices is a major cause of nosocomial diseases and infections. Extensive research is directed at inhibiting the formation and maturation of such biofilms. Natural plant-derived phenolic compounds have promising antimicrobial effects against drug-resistant bacteria. The anti-biofilm activity of two selected phenolic compounds (vanillin and syringic acid) was tested against three biofilm-forming methicillin-resistant S. epidermidis strains with different genotypes. Resazurin assay combining crystal violet staining and confocal microscopy was used for biofilm and extracellular polymer substance (EPS) inhibition tests. Effects on EPS compounds such as proteins, extracellular DNA, and polysaccharides were also examined. Combined with quantitative real-time PCR of selected agr quorum-sensing systems and biofilm genetic determinants, our complex analysis of vanillin and syringic acid showed similar biofilm and EPS inhibition effects on S. epidermidis strains, reducing biofilm formation up to 80% and EPS up to 55%, depending on the genotype of the tested strain. Natural antimicrobial agents are thus potentially useful inhibitors of biofilms. 相似文献
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目的从表皮葡萄球菌发酵液中分离纯化脂肽粗提物,并分析其生物学活性。方法通过酸沉淀分离和有机溶剂抽提的方法,从表皮葡萄球菌1457发酵液中得到脂肽粗提物。利用排油圈试验和薄层色谱(TLC)分析脂肽粗提物的性质,HPLC分析其纯度。小鼠皮下注射脂肽粗提物后,再经皮肤感染金黄葡萄球菌,检测其对小鼠体内白细胞的影响及抑菌作用;实时定量PCR检测其对小鼠体内β防御素14(mBD14)表达的影响。结果所得脂肽粗提物F2的排油活性大于F1;TLC分析显示,F2中存在性质相近的脂肽类同系物,纯度>60%;脂肽粗提物能减缓小鼠因感染金黄葡萄球菌引起的急性炎症,降低由感染引起的白细胞增多,并通过上调mBD14的表达抑制细菌在皮肤内的增殖。结论已从表皮葡萄球菌发酵液中成功获得了具有生物学活性的新型脂肽粗提物。 相似文献
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目的分析表皮葡萄球菌耐药性与生物被膜的相关性。方法采用刚果红平板法检测表皮葡萄球菌胞间多糖黏附素(PIA);半定量生物被膜形成试验检测生物被膜表型;采用二倍稀释法检测各药物对该菌的最低抑菌浓度(MIC)。结果42株表皮葡萄球菌中,9株为PIA+/生物被膜表型+,4株为PIA+/生物被膜表型-,29株为PIA-/生物被膜表型-;3组菌对苯唑西林、克林霉素、阿米卡星、左氧氟沙星和阿莫西林/克林霉素的耐药性差异有统计学意义;万古霉素和阿莫西林/克拉维酸对3组菌的MIC低于NCCLS给出的敏感值,青霉素、苯唑西林、克林霉素、红霉素和头孢西丁对3组菌的MIC则远远高于NCCLS给出的敏感值,且β-内酰胺类的3种药物对3组菌的MIC差异有统计学意义。结论表皮葡萄球菌生物被膜形成是多基因调控过程,在细菌耐药中具有重要作用。 相似文献
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Itzia S. Gmez-Alonso Sergio Martínez-García Gabriel Betanzos-Cabrera Esmeralda Jurez María C. Sarabia-Len María Teresa Herrera Fernando Gmez-Chvez Luvia Sanchez-Torres Sandra Rodríguez-Martínez Mario E. Cancino-Diaz Jorge Cancino Juan C. Cancino-Diaz 《International journal of molecular sciences》2022,23(9)
Neutrophils play a crucial role in eliminating bacteria that invade the human body; however, cathepsin G can induce biofilm formation in a non-biofilm-forming Staphylococcus epidermidis 1457 strain, suggesting that neutrophil proteases may be involved in biofilm formation. Cathepsin G, cathepsin B, proteinase-3, and metalloproteinase-9 (MMP-9) from neutrophils were tested on the biofilm induction in commensal (skin isolated) and clinical non-biofilm-forming S. epidermidis isolates. From 81 isolates, 53 (74%) were aap+, icaA−, icaD− genotype, and without the capacity of biofilm formation under conditions of 1% glucose, 4% ethanol or 4% NaCl, but these 53 non-biofilm-forming isolates induced biofilm by the use of different neutrophil proteases. Of these, 62.3% induced biofilm with proteinase-3, 15% with cathepsin G, 10% with cathepsin B and 5% with MMP -9, where most of the protease-induced biofilm isolates were commensal strains (skin). In the biofilm formation kinetics analysis, the addition of phenylmethylsulfonyl fluoride (PMSF; a proteinase-3 inhibitor) showed that proteinase-3 participates in the cell aggregation stage of biofilm formation. A biofilm induced with proteinase-3 and DNAse-treated significantly reduced biofilm formation at an early time (initial adhesion stage of biofilm formation) compared to untreated proteinase-3-induced biofilm (p < 0.05). A catheter inoculated with a commensal (skin) non-biofilm-forming S. epidermidis isolate treated with proteinase-3 and another one without the enzyme were inserted into the back of a mouse. After 7 days of incubation period, the catheters were recovered and the number of grown bacteria was quantified, finding a higher amount of adhered proteinase-3-treated bacteria in the catheter than non-proteinase-3-treated bacteria (p < 0.05). Commensal non-biofilm-forming S. epidermidis in the presence of neutrophil cells significantly induced the biofilm formation when multiplicity of infection (MOI) 1:0.01 (neutrophil:bacteria) was used, but the addition of a cocktail of protease inhibitors impeded biofilm formation. A neutrophil:bacteria assay did not induce neutrophil extracellular traps (NETs). Our results suggest that neutrophils, in the presence of commensal non-biofilm-forming S. epidermidis, do not generate NETs formation. The effect of neutrophils is the production of proteases, and proteinase-3 releases bacterial DNA at the initial adhesion, favoring cell aggregation and subsequently leading to biofilm formation. 相似文献
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Rahman RN Kamarudin NH Yunus J Salleh AB Basri M 《International journal of molecular sciences》2010,11(9):3195-3208
An organic solvent tolerant lipase gene from Staphylococcus epidermidis AT2 was successfully cloned and expressed with pTrcHis2 in E. coli TOP10. Sequence analysis revealed an open reading frame (ORF) of 1,933 bp in length which coded for a polypeptide of 643 amino acid residues. The polypeptide comprised of a signal peptide (37 amino acids), pro-peptide and a mature protein of 390 amino acids. Expression of AT2 lipase resulted in an 18-fold increase in activity, upon the induction of 0.6 mM IPTG after a 10 h incubation period. Interestingly, this lipase was stable in various organic solvents (25% (v/v), mainly toluene, octanol, p-xylene and n-hexane). Literature shows that most of the organic solvent stable bacterial lipases were produced by Pseudomonas sp. and Bacillus sp., but very few from Staphylococcus sp. This lipase demonstrates great potential to be employed in various industrial applications. 相似文献
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Staphylococcus epidermidis is a bacterium that is part of the human microbiota. It is most abundant on the skin, in the respiratory system and in the human digestive tract. Also, Staphylococcus aureus contributes to human infections and has a high mortality rate. Both of these bacterial species produce biofilm, a pathogenic factor increasing their resistance to antibiotics. For this reason, we are looking for new substances that can neutralize bacterial cells. One of the best-known substances with such effects are silver nanoparticles. They exhibited antibacterial and antibiofilm formation activity that depended on their size, shape and the concentration used. In this review, we presented the data related to the use of silver nanoparticles in counteracting bacterial growth and biofilm formation published in scientific papers between 2017 and 2021. Based on the review of experimental results, the properties of nanoparticles prompt the expansion of research on their activity. 相似文献