抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

Microfabricated integrated circuits revolutionized computation by vastly reducing the space, labor, and time required for calculations. Microfluidic systems hold similar promise for the large-scale automation of chemistry and biology, suggesting the possibility of numerous experiments performed rapidly and in parallel, while consuming little reagent. While it is too early to tell whether such a vision will be realized, significant progress has been achieved, and various applications of significant scientific and practical interest have been developed. Here a review of the physics of small volumes (nanoliters) of fluids is presented, as parametrized by a series of dimensionless numbers expressing the relative importance of various physical phenomena. Specifically, this review explores the Reynolds number Re, addressing inertial effects; the Peclet number Pe, which concerns convective and diffusive transport; the capillary number Ca expressing the importance of interfacial tension; the Deborah, Weissenberg, and elasticity numbers De, Wi, and El, describing elastic effects due to deformable microstructural elements like polymers; the Grashof and Rayleigh numbers Gr and Ra, describing density-driven flows; and the Knudsen number, describing the importance of noncontinuum molecular effects. Furthermore, the long-range nature of viscous flows and the small device dimensions inherent in microfluidics mean that the influence of boundaries is typically significant. A variety of strategies have been developed to manipulate fluids by exploiting boundary effects; among these are electrokinetic effects, acoustic streaming, and fluid-structure interactions. The goal is to describe the physics behind the rich variety of fluid phenomena occurring on the nanoliter scale using simple scaling arguments, with the hopes of developing an intuitive sense for this occasionally counterintuitive world.

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Microfluidics: Fluid physics at the nanoliter scale

Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13

In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28

Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37



Figure 1

Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.



In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.

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Gold nanoparticles in chemical and biological sensing.

5.1. Detection Formats 475 5.2. Food Quality and Safety Analysis 477 5.2.1. Pathogens 477 5.2.2. Toxins 479 5.2.3. Veterinary Drugs 479 5.2.4. Vitamins 480 5.2.5. Hormones 480 5.2.6. Diagnostic Antibodies 480 5.2.7. Allergens 481 5.2.8. Proteins 481 5.2.9. Chemical Contaminants 481 5.3. Medical Diagnostics 481 5.3.1. Cancer Markers 481 5.3.2. Antibodies against Viral Pathogens 482 5.3.3. Drugs and Drug-Induced Antibodies 483 5.3.4. Hormones 483 5.3.5. Allergy Markers 483 5.3.6. Heart Attack Markers 484 5.3.7. Other Molecular Biomarkers 484 5.4. Environmental Monitoring 484 5.4.1. Pesticides 484 5.4.2. 2,4,6-Trinitrotoluene (TNT) 485 5.4.3. Aromatic Hydrocarbons 485 5.4.4. Heavy Metals 485 5.4.5. Phenols 485 5.4.6. Polychlorinated Biphenyls 487 5.4.7. Dioxins 487 5.5. Summary 488 6. Conclusions 489 7. Abbreviations 489 8. Acknowledgment 489 9. References 489

Surface Plasmon Resonance Sensors for Detection of Chemical and Biological Species

OBJECTIVE To identify the prevalence of multidrug-resistant (MDR) bacteria and identify their specific risk factors in routine urine specimens of spinal cord injury (SCI) patients. METHODS This study was designed in a retrospective manner, reviewing the medical records of SCI patients who were admitted to a specialized SCI unit between January 2001 and December 2013. Patients were investigated for age, gender, American Spinal Injury Association impairment scale, SCI level, duration after injury, bladder management method, and hospitalization history within four weeks prior to visiting our unit. The results of routine urine cultures including presence of MDR organisms were analyzed. RESULTS Among the total 2,629 urine samples from the newly admitted SCI patients, significant bacteriuria was identified in 1,929 (73.4%), and MDR organisms were isolated in 29 (1.1%) cultures. There was an increasing trend of MDR organism prevalence from 2001 to 2013 (p<0.01). The isolation of MDR organisms in inpatients who were admitted for rehabilitation (1.3%) was significantly higher than it was among community-residing persons (0.2%) (p<0.05). By voiding method, patients who used a suprapubic indwelling catheter (3.3%) or a urethral indwelling catheter (2.6%) showed a higher rate of MDR organism isolation (p<0.05). CONCLUSION There was an increasing trend of MDR organism isolation in SCI patients. Inpatients and persons who used indwelling catheters showed a higher risk of MDR organism isolation.

/pdf/prevalence-of-and-risk-factors-for-multidrug-resistant-47e38lvzf2.pdf

Prevalence of and Risk Factors for Multidrug-Resistant Bacteria in Urine Cultures of Spinal Cord Injury Patients.

Positively charged carbon electrocatalyst for enhanced power performance of L-ascorbic acid fuel cells

Laboratoire d’Electrochimie Physique et Analytique, Station 6, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, SwitzerlandReceived December 18, 2011, Accepted February 27, 2012Voltammetric characterization of hydrophilic anion transfer processes across a 66 microhole array interfacebetween the water and polyvinylchloride-2-nitrophenyloctylether gel layer is demonstrated. Since the transferof hydrophilic anions including Br

Voltammetric Studies of Anion Transfer Reactions Across a Microhole Array-Water/PVC-NPOE Gel Interface

A substrate for testing a carrier liquid for biomolecules using SPR or other techniques provides a metallic island surrounded by a hydrophobic layer, the islands being a location for the attachment of probe molecules. The hydrophobic layer may also be a dielectric material providing improved sensitivity in SPR imaging.

Hye Jin Lee

Papers

Prevalence of and Risk Factors for Multidrug-Resistant Bacteria in Urine Cultures of Spinal Cord Injury Patients.

Positively charged carbon electrocatalyst for enhanced power performance of L-ascorbic acid fuel cells

Voltammetric Studies of Anion Transfer Reactions Across a Microhole Array-Water/PVC-NPOE Gel Interface

Versatile substrate for SPR detection

Ionode detection and capillary electrophoresis integrated on a polymer micro-chip