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

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

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.

Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

Phenolics are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potent antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. In the last few years, the identification and development of phenolic compounds or extracts from different plants has become a major area of health- and medical-related research. This review provides an updated and comprehensive overview on phenolic extraction, purification, analysis and quantification as well as their antioxidant properties. Furthermore, the anticancer effects of phenolics in-vitro and in-vivo animal models are viewed, including recent human intervention studies. Finally, possible mechanisms of action involving antioxidant and pro-oxidant activity as well as interference with cellular functions are discussed.

/pdf/plant-phenolics-extraction-analysis-and-their-antioxidant-2ee2ft7zgl.pdf

Plant phenolics: extraction, analysis and their antioxidant and anticancer properties.

A new detector of water based on the piezoelectric crystal with separated electrode (PCSE) is proposed. The frequency response of the PCSE to the dielectric constant of nonelectrolyte solution is derived. The detector was applied to determine the microcontent of water in organic solvents. The detection limits are 0.022, 0.013 and 0.010 g/L in acetone, tetrahydrofuran, and dioxane, respectively. For the water content in ethanol, linear and nonlinear regression methods are employed, and the average relative errors of prediction are 1.67% and 2.77%, respectively

Piezoelectric detection of water with a separated electrode

The effect of the size of the molecularly imprinted polymers (MIPs) on the piezoelectric quartz crystal (PQC) sensor performance was investigated. Erythromycin imprinted polymers microspheres with different sizes were synthesized by precipitation polymerization. The size of the MIPs was characterized by using transmission electron microscope (TEM) analysis. Being coated with a poly(vinyl chloride) (PVC) membrane containing MIPs, the proposed PQC sensor can selectively adsorb the template molecule. Investigation of the performance of sensors modified with different sizes of MIPs showed that PQC sensor modified with smaller size MIPs exhibited better performance and excellent selectivity. Other influencing factors on sensor functions modified with different sizes MIPs were also investigated.

Effect of the size of molecularly imprinted polymers sensing materials on piezoelectric quartz crystal sensor performance.

Ion chromatographic determination of calcium and magnesium cations in human saliva and urine with a piezoelectric detector.

A Series Piezoelectric Quartz Crystal Microbial Sensing Technique Used for Biochemical Oxygen Demand Assay in Environmental Monitoring

We developed a highly specific sensing platform for the sequential detection of two analytes in a homogenous solution by using colorimetric and fluorescence methods. This design used aptamer units [thiolated aptamer I (Apt I) for platelet-derived growth factor BB (PDGF-BB); fluorescein amidite (FAM)-labeled aptamer II (Apt II) for adenosine]. A bifunctional aptasensor was prepared by the self-assembly of thiolated Apt I on gold nanoparticles (AuNPs) and partial hybridization between Apt I and Apt II. The fabricated bifunctional aptasensor was used to detect two targets (PDGF-BB and adenosine) sequentially and selectively in a homogenous solution. In the presence of target molecules PDGF-BB, the color and absorbance of the aptamer-modified AuNPs changed because of AuNP aggregation. The increase of fluorescence intensity of FAM at 520 nm was used to analyze adenosine in the test system. The proposed aptasensor had low detection limit, high sensitivity, and bifunctional recognition and was successfully used for real serum samples. It also highlights promising applications for other aptamers and a broad range of other analytes.

Shouzhuo Yao

Papers

Piezoelectric detection of water with a separated electrode

Effect of the size of molecularly imprinted polymers sensing materials on piezoelectric quartz crystal sensor performance.

Ion chromatographic determination of calcium and magnesium cations in human saliva and urine with a piezoelectric detector.

A Series Piezoelectric Quartz Crystal Microbial Sensing Technique Used for Biochemical Oxygen Demand Assay in Environmental Monitoring

A colorimetric and fluorescence sensing platform for two analytes in homogenous solution based on aptamer-modified gold nanoparticles