There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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

Recent developments have greatly improved the sensitivity of optical sensors based on metal nanoparticle arrays and single nanoparticles. We introduce the localized surface plasmon resonance (LSPR) sensor and describe how its exquisite sensitivity to size, shape and environment can be harnessed to detect molecular binding events and changes in molecular conformation. We then describe recent progress in three areas representing the most significant challenges: pushing sensitivity towards the single-molecule detection limit, combining LSPR with complementary molecular identification techniques such as surface-enhanced Raman spectroscopy, and practical development of sensors and instrumentation for routine use and high-throughput detection. This review highlights several exceptionally promising research directions and discusses how diverse applications of plasmonic nanoparticles can be integrated in the near future.

Biosensing with plasmonic nanosensors

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

Synthesis of Highly Fluorescent Gold Nanoparticles for Sensing Mercury(II)

F gold nanoclusters (Au NCs) or nanodots (NDs) with sizes smaller than 3 nm are a specific type of gold nanomaterials. In this review, Au NCs are used to represent fluorescent Au nanomaterials with sizes smaller than 3 nm. Unlike the most popular and well-known spherical, large gold nanoparticles, Au NCs do not exhibit surface plasmon resonance (SPR) absorption in the visible region but have fluorescence in the visible to near-infrared (NIR) region. With advantages of long lifetime, large Stokes shift, and biocompatibility, Au NCs have become interesting sensing and imaging materials. Although Au NCs prepared from Au in the presence of small thiol compounds such as 2-phenylethanethiol (PhCH2CH2SH) have been reported over the past decade, 5 their use for bioapplications have not been well recognized, mainly because of their low quantum yield (usually less than 1%), poor water dispersibility, photo and chemical instability, and difficulty for conjugation. In the past decade, many strategies for the preparation of stable, water dispersible, highly fluorescent, and biocompatible Au NCs have been reported. There are two major categories elucidating the recent advanced techniques for the preparation of Au NCs. The first category is through etching of larger sizes of nonfluorescent gold nanoparticles (Au NPs) by thiol compounds such as mercaptopropionic acid. The second category is from reduction of Au in the presence of a ligand or template (protein) such as bovine serum albumin (BSA). The optical properties of biocompatible Au NCs are dependent on their size, surface ligand or template, and the surrounding medium, and thus they can be studied to develop sensitive and selective sensing and imaging systems for the detection of various analytes. The growing popularity of Au NCs in analytical applications has been realized in these few years. Several excellent review papers dealing with Au NCs from the viewpoint of analytical chemistry have been reported to highlight their potential for the analysis of environmental and biological samples. This review focuses on recent advances in Au NCs based sensing and imaging systems between 2012 and 2014. Current challenges and future prospects of Au NCs for fundamental studies and analytical applications will be provided.

Fluorescent Gold Nanoclusters: Recent Advances in Sensing and Imaging

We have developed a highly specific sensing system for platelet-derived growth factors (PDGFs) and platelet-derived growth factor receptors (PDGFR) that uses gold nanoparticles (GNPs). We synthesized GNPs modified with an aptamer (Apt-GNPs) that is specific to PDGFs and used them to detect PDGFs by monitoring the changes in the color and extinction of the Apt-GNPs that occur as a result of aggregation. The color of the Apt-GNPs changes from red to purple at low concentrations ( 400 nM). We found that the sensitivity of the Apt-GNPs for the three PDGFs is highly salt-dependent, with an optimum condition of 200 mM NaCl. We obtained biphasic curves when plotting of the ratios of the extinction coefficients of the Apt-GNPs at 650 and 530 nm against the concentrations of PDGF-AA at various concentrations of Apt-GNPs. The linear ranges of the increases and decreases in this extinction ratio are 2.5−10 and 10−20 nM, respectively, for 0.42 nM Apt-GNPs ...

Aptamer-Modified Gold Nanoparticles for Colorimetric Determination of Platelet-Derived Growth Factors and Their Receptors

Synthesis of high-quality carbon nanodots from hydrophilic compounds: role of functional groups

A new gold-nanoparticle (AuNP)-based sensor for detecting Hg(II) ions in aqueous solution has been developed. Rhodamine B (RB) molecules that are highly fluorescent in bulk solution fluoresce weakly when they are adsorbed onto AuNP surfaces as a result of fluorescence resonance energy transfer and collision with AuNPs. In the presence of metal ions such as Hg(II), RB molecules are released from the AuNP surface and thus restore the florescence of RB. The modulation of the photoluminescence quenching efficiency of RB−AuNPs in the presence of Hg(II) ions can achieve a large turn-on fluorescence enhancement (400-fold) in aqueous solution, and the entire detection takes less than 10 min. We have improved the selectivity of the probe further by modifying the AuNP surfaces with thiol ligands (mercaptopropionic acid, mercaptosuccinic acid, and homocystine) and adding a chelating ligand (2,6-pyridinedicarboxylic acid) to the sample solutions. Under the optimum conditions, the selectivity of this system for Hg(II)...

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Huan-Tsung Chang

Papers

Synthesis of Highly Fluorescent Gold Nanoparticles for Sensing Mercury(II)

Fluorescent Gold Nanoclusters: Recent Advances in Sensing and Imaging

Aptamer-Modified Gold Nanoparticles for Colorimetric Determination of Platelet-Derived Growth Factors and Their Receptors

Synthesis of high-quality carbon nanodots from hydrophilic compounds: role of functional groups

Selective Gold-Nanoparticle-Based “Turn-On” Fluorescent Sensors for Detection of Mercury(II) in Aqueous Solution