A Hierarchical 3D Nanostructured Microfluidic Device for Sensitive Detection of Pathogenic Bacteria

Efficient capture and rapid detection of pathogenic bacteria from body fluids lead to early diagnostics of bacterial infections and significantly enhance the survival rate. We propose a universal nano/microfluidic device integrated with a 3D nanostructured detection platform for sensitive and quantifiable detection of pathogenic bacteria. Surface characterization of the nanostructured detection platform confirms a uniform distribution of hierarchical 3D nano‐/microisland (NMI) structures with spatial orientation and nanorough protrusions. The hierarchical 3D NMI is the unique characteristic of the integrated device, which enables enhanced capture and quantifiable detection of bacteria via both a probe‐free and immunoaffinity detection method. As a proof of principle, we demonstrate probe‐free capture of pathogenic Escherichia coli (E. coli) and immunocapture of methicillin‐resistant‐Staphylococcus aureus (MRSA). Our device demonstrates a linear range between 50 and 10⁴ CFU mL^?1, with average efficiency of 93% and 85% for probe‐free detection of E. coli and immunoaffinity detection of MRSA, respectively. It is successfully demonstrated that the spatial orientation of 3D NMIs contributes in quantifiable detection of fluorescently labeled bacteria, while the nanorough protrusions contribute in probe‐free capture of bacteria. The ease of fabrication, integration, and implementation can inspire future point‐of‐care devices based on nanomaterial interfaces for sensitive and high‐throughput optical detection.     

大菱鲆出血症病原菌的分离和鉴定

从患病大菱鲆体内分离到一株病原菌SMP1,经人工感染试验计算出SMP1的半致死量LD50 =1.94× 10 6 。药敏实验表明氟哌酸、丙氟哌酸、复合磺胺、氯霉素、四环素对SMP1有较强的抑制作用。BIOLOG细菌鉴定系统不能对SMP1鉴定。综合形态观察、生理生化特征、16SrDNA、溶血素基因保守区分析等实验结果 ,可将SMP1鉴定为鳗弧菌。     

低聚壳聚糖复配体系对皮肤致病菌的体外抗菌活性研究

采用药敏纸片法和对倍稀释法分别考察了低聚壳聚糖与茶树油对化脓性链球菌、表皮葡萄球菌、金黄色葡萄球菌和大肠杆菌的抑菌性和最小抑菌浓度(MIC);采用定量法测定了低聚壳聚糖和茶树油复配体系的杀菌率,并与单组分杀菌率进行对比。结果表明:低聚壳聚糖和茶树油对4种实验菌均有抑菌性的MIC分别为0.5g/L和7.50mL/L;0.5g/L低聚壳聚糖与7.50mL/L茶树油复配后,对4种实验菌均有优异的杀菌率,复配体系明显优于单组分杀菌效果,其20min杀菌率均达到100%。     

Antibacterial Action of Chemically Synthesized and Laser Generated Silver Nanoparticles against Human Pathogenic Bacteria

Silver nanoparticles in the range of 10–40 nm were synthesized chemically and by laser ablation, employed for in vitro antibacterial action against human pathogenic bacterium. Their formation was evidenced by UV-visible spectrophotometer; particle size confirmed by atomic force microscopy, crystal structure determined by X-ray diffraction and chemical composition investigated by Fourier transform infrared spectroscopy. The calculated MIC(minimum inhibitory concentration) of chemically synthesized nanoparticles with 30–40 nm in size are 2.8 μg/m L, 4.37 μg/m L, 13.5 μg/m L and 2.81 μg/m L for E. coli, S. aureus, B. subtillis and Salmonella, respectively. Whereas laser ablated nanoparticles exhibit MIC of 2.10 μg/m L, 2.36 μg/m L and 2.68 μg/m L for E. coli, S. aureus and Salmonella, respectively.     

Biomimetic Nanosponges Suppress In Vivo Lethality Induced by the Whole Secreted Proteins of Pathogenic Bacteria

Polymeric nanoparticles coated with membrane of intact red blood cells have emerged as biomimetic toxin nanosponges (RBC‐NS) that absorb and neutralize bacterial virulence factors associated with numerous bacterial infections. Despite its promise, a clear correlation between in vitro neutralization of complex bacterial toxins and in vivo therapeutic efficacy remains elusive. In this study, the whole secreted proteins (wSP) of methicillin‐resistant Staphylococcus aureus (MRSA) are collected to induce lethality in mice. The wSP preserve the complexity of bacterial virulence profile while avoiding the intricacy and dynamics of infections by live bacteria. RBC‐NS are first quantified for their neutralization capacity against the hemolytic activity of MRSA wSP in vitro. Using a mouse model, in vivo studies further demonstrate that, by neutralizing the hemolytic activity, RBC‐NS confer significant survival benefits against wSP‐induced lethality. Furthermore, when mice are challenged with a sublethal dosage of MRSA supernatant, RBC‐NS reduce lung damages and inhibit the activation of nuclear factor kappa B in the spleen. These results provide a systematic evaluation of RBC‐NS toward the treatment of severe MRSA infections such as MRSA bacteremia and MRSA‐induced sepsis.     

Detection and Inhibition of Bacteria on a Dual‐Functional Silver Platform

Detection and inhibition of bacteria are universally required in clinics and daily life for health care. Developing a dual‐functional material is challenging and in demand, engaging advanced applications for both defined bioanalysis and targeted biotoxicity. Herein, magnetic silver nanoshells are designed as a multifunctional platform for the detection and inhibition of bacteria. The optimized magnetic silver nanoshells enable direct laser desorption/ionization mass spectrometry based metabolic analysis of bacteria (≈10 µL^?1), in complex biofluids. The serum infection process (0–10 h) is monitored by statistics toward clinical classification. Moreover, magnetic silver nanoshells facilitate surface adhesion on bacteria due to nanoscale surface roughness and thus display long‐term antibacterial effects. Bacteria metabolism is studied with metabolic biomarkers (e.g., malate and lysine) identified during inhibition, showing cell membrane destruction and dysfunctional protein synthesis mechanisms. This work not only guides the design of material‐based approaches for bioanalysis and biotoxicity, but contributes to bacteria‐related diagnosis by using specific metabolic biomarkers for sensitive detection and new insights by monitoring metabolomic change of bacteria for antibacterial applications.     

Nanomotion Detection Method for Testing Antibiotic Resistance and Susceptibility of Slow‐Growing Bacteria

Infectious diseases are caused by pathogenic microorganisms and are often severe. Time to fully characterize an infectious agent after sampling and to find the right antibiotic and dose are important factors in the overall success of a patient's treatment. Previous results suggest that a nanomotion detection method could be a convenient tool for reducing antibiotic sensitivity characterization time to several hours. Here, the application of the method for slow‐growing bacteria is demonstrated, taking Bordetella pertussis strains as a model. A low‐cost nanomotion device is able to characterize B. pertussis sensitivity against specific antibiotics within several hours, instead of days, as it is still the case with conventional growth‐based techniques. It can discriminate between resistant and susceptible B. pertussis strains, based on the changes of the sensor's signal before and after the antibiotic addition. Furthermore, minimum inhibitory and bactericidal concentrations of clinically applied antibiotics are compared using both techniques and the suggested similarity is discussed.     

USB2.0技术在色差法检测乳品菌群中的应用

将USB芯片应用到色差法检测乳品菌群,是将所采集到的视频信号传给PC机,然后由相应的客户软件进行处理.最终得出乳品中菌群的含量.具有操作方便.实时快速,检测误差小,当菌群浓度大于41万/mL时,测量误差不大于10%,同时将PC机应用到乳品检测领域,可充分发挥了计算机快速,准确,为企业赢得了时间,降低了成本.     

A Quantitative Bacteria Monitoring and Killing Platform Based on Electron Transfer from Bacteria to a Semiconductor

A platform with both bacteria killing and sensing capabilities is crucial for monitoring the entire bacteria-related process on biomaterials and biomedical devices. Electron transfer (ET) between the bacteria and a Au-loaded semiconductor (ZnO) is observed to be the primary factor for effective bacteria sensing and fast bacteria killing. The electrons produce a saturation current that varies linearly with the bacteria number, semi-logarithmically, with R² of 0.98825, thus providing an excellent tool to count bacteria quantitatively in real-time. Furthermore, ET leads to continuous electron loss killing of about 80% of Escherichia coli in only 1 h without light. The modularity and extendability of this ET-based platform are also demonstrated by the excellent results obtained from other semiconductor/substrate systems and the stability is confirmed by recycling tests. The underlying mechanism for the dual functions is not due to conventional attributed Zn²⁺ leaching or photocatalysis but instead electrical interactions upon direct contact. The results reveal the capability of real-time detection of bacteria based on ET while providing information about the antibacterial behavior of ZnO-based materials especially in the early stage. The concept can be readily incorporated into the design of smart and miniaturized devices that can sense and kill bacteria simultaneously.     

粪菌低温保存的研究进展

肠道菌群在人类和动物的健康方面起着越来越重要的作用,而粪便样本的保存质量对研究结果有直接影响。本文归纳了粪菌保存的主要作用,介绍了低温保存的机制,总结粪菌的保存方法,包括冷冻保存、冷冻干燥保存、冷藏保存和其他非低温保存方式,表明在-80 ℃下冷冻的样本具有较稳定的DNA和微生物群落,提出添加有效的低温保护剂能阻止冰晶形成,提高粪菌活性。探讨了影响样本保存效果的主要因素,并对未来具有可行性的新方法进行展望。     

纳米酶:对抗细菌的新策略

由细菌引发的相关疾病和环境污染等问题引起了人们的高度重视,同时随着抗生素的使用,细菌的耐药性逐渐增强,人们急需开发新型抗菌剂。诸如溶菌酶、髓过氧化物酶等天然酶具有显著的抗菌能力,但其作为抗菌剂存在保质期短、生产成本高等缺点,很难大规模生产。因此,人们正探索寻求天然酶的替代品。纳米酶是新一代人工模拟酶,兼具纳米材料独特的理化性质和类酶催化活性,因其结构稳定、生产成本低等优点受到广泛关注。本文综述了纳米酶的抗菌机制和近期抗菌纳米酶的主要研究进展,并对未来该领域的研究进行展望。     

发光细菌的研究和应用

发光细菌是一类在正常的生理条件下能够发射可见荧光的细菌，主要分布在海洋环境中。发光细菌及其发光基因在环境监测等领域中具有广泛的应用价值。本文综述了发光细菌的分类、发光机理及其应用。     

A Nanophotonic Structure Containing Living Photosynthetic Bacteria

Photosynthetic organisms rely on a series of self‐assembled nanostructures with tuned electronic energy levels in order to transport energy from where it is collected by photon absorption, to reaction centers where the energy is used to drive chemical reactions. In the photosynthetic bacteria Chlorobaculum tepidum, a member of the green sulfur bacteria family, light is absorbed by large antenna complexes called chlorosomes to create an exciton. The exciton is transferred to a protein baseplate attached to the chlorosome, before migrating through the Fenna–Matthews–Olson complex to the reaction center. Here, it is shown that by placing living Chlorobaculum tepidum bacteria within a photonic microcavity, the strong exciton–photon coupling regime between a confined cavity mode and exciton states of the chlorosome can be accessed, whereby a coherent exchange of energy between the bacteria and cavity mode results in the formation of polariton states. The polaritons have energy distinct from that of the exciton which can be tuned by modifying the energy of the optical modes of the microcavity. It is believed that this is the first demonstration of the modification of energy levels within living biological systems using a photonic structure.     

产淀粉酶菌的筛选和诱变

淀粉酶在造纸工业中被广泛利用,淀粉酶的需求量越来越大,获得高产淀粉酶菌株是解决该问题的重要途径。采用透明圈法筛选获得 3 株产淀粉酶的细菌,并对它们进行紫外光和超声波诱变研究,探究其产淀粉酶的最佳诱变条件。实验结果显示,菌株紫外光诱变的适宜照射时间为 30 s,最佳照射距离为 15 cm,C1 菌和 S 菌的诱变效果较好,在此条件下的比透明圈都为 3.00。超声波诱变的适宜时间为 20 min,C1 菌和 S 菌的比透明圈都为 2.50。 研究表明,紫外光和超声波诱变都能提高产酶量,紫外光诱变的效果较超声 波诱变更稳定,超声波诱变后的产酶量低于紫外光诱变。     

硫酸盐还原菌腐蚀研究进展

在油田注水系统和工业循环冷却水系统中,硫酸盐还原菌（SRB）是微生物腐蚀（MIC）的主要原因之一。硫酸盐还原菌对金属的腐蚀主要表现在SRB的生长代谢在金属表面形成生物膜,改变了生物膜内微环境,其代谢产物与金属基体相互作用,加速了金属的腐蚀过程。从硫酸盐还原菌的微生物生理学,SRB的腐蚀机理,SRB对材料的腐蚀,SRB腐蚀研究方法和SRB腐蚀防治等几个方面,对微生物腐蚀的近期研究状况进行综述,并展望了微生物腐蚀研究的近期发展趋势。     

致病性鳗弧菌金属蛋白酶基因克隆及序列分析

从我国山东沿海发病的鲈鱼（Lateolabrax japonicus）分离到一株致病性鳗弧菌（Vibrio anguillarum）W-1，该菌的胞外蛋白酶活性为4226u/ml，部分纯化的胞外蛋白酶对海水养殖大菱鲆鱼有一定的毒性。应用PCR扩增，从鳗弧菌W-1染色体DNA扩增出一条长约1.925kb的特异性PCR产物，DNA序列分析表明：克隆的片段含有完整的金属蛋白酶基因阅读框，编码611个氨基酸残基的蛋白质，该金属蛋白酶基因与一株致病性鳗弧菌蛋白酶基因的核苷酸及氨基酸序列同源性为100%，而与解蛋白弧菌（V.proteolyticus)、创作弧菌（V.vulnificus）、霍乱弧菌（V.cholerae)、斑点气单胞菌（Aeromonas punctata），嗜水气单胞菌（Aeromonas hydrophila）的氨基酸序列同源性分别为73%、70%、69%、53%、51%。