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

Signaling Recognition Events with Fluorescent Sensors and Switches.

In the last 10 years the field of molecular diagnostics has witnessed an explosion of interest in the use of nanomaterials in assays for gases, metal ions, and DNA and protein markers for many diseases. Intense research has been fueled by the need for practical, robust, and highly sensitive and selective detection agents that can address the deficiencies of conventional technologies. Chemists are playing an important role in designing and fabricating new materials for application in diagnostic assays. In certain cases assays based upon nanomaterials have offered significant advantages over conventional diagnostic systems with regard to assay sensitivity, selectivity, and practicality. Some of these new methods have recently been reviewed elsewhere with a focus on the materials themselves or as subclassifications in more generalized overviews of biological applications of nanomaterials.1-7 We intend to review some of the major advances and milestones in the field of detection systems based upon nanomaterials and their roles in biodiagnostic screening for nucleic acids, * To whom correspondence should be addressed. Phone: 847-4913907. Fax: 847-467-5123. E-mail: chadnano@northwestern.edu. Nathaniel L. Rosi earned his B.A. degree at Grinnell College (1999) and his Ph.D. degree from the University of Michigan (2003), where he studied the design, synthesis, and gas storage applications of metal−organic frameworks under the guidance of Professor Omar M. Yaghi. In 2003 he began postdoctoral studies as a member of Professor Mirkin’s group at Northwestern University. His current research focuses on the rational assembly of DNA-modified nanostructures into larger-scale materials.

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Nanostructures in Biodiagnostics

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.

I read this book the same weekend that the Packers took on the Rams, and the experience of the latter event, obviously, colored my judgment. Although I abhor anything that smacks of being a handbook (like, \"How to Earn a Merit Badge in Neurosurgery\") because too many volumes in biomedical science already evince a boyscout-like approach, I must confess that parts of this volume are fast, scholarly, and significant, with certain reservations. I like parts of this well-illustrated book because Dr. Sj6strand, without so stating, develops certain subjects on technique in relation to the acquisition of judgment and sophistication. And this is important! So, given that the author (like all of us) is somewhat deficient in some areas, and biased in others, the book is still valuable if the uninitiated reader swallows it in a general fashion, realizing full well that what will be required from the reader is a modulation to fit his vision, propreception, adaptation and response, and the kind of problem he is undertaking. A major deficiency of this book is revealed by comparison of its use of physics and of chemistry to provide understanding and background for the application of high resolution electron microscopy to problems in biology. Since the volume is keyed to high resolution electron microscopy, which is a sophisticated form of structural analysis, but really morphology in a modern guise, the physical and mechanical background of The instrument and its ancillary tools are simply and well presented. The potential use of chemical or cytochemical information as it relates to biological fine structure , however, is quite deficient. I wonder when even sophisticated morphol-ogists will consider fixation a reaction and not a technique; only then will the fundamentals become self-evident and predictable and this sine qua flon will become less mystical. Staining reactions (the most inadequate chapter) ought to be something more than a technique to selectively enhance contrast of morphological elements; it ought to give the structural addresses of some of the chemical residents of cell components. Is it pertinent that auto-radiography gets singled out for more complete coverage than other significant aspects of cytochemistry by a high resolution microscopist, when it has a built-in minimal error of 1,000 A in standard practice? I don't mean to blind-side (in strict football terminology) Dr. Sj6strand's efforts for what is \"routinely used in our laboratory\"; what is done is usually well done. It's just that …

Methods in Enzymology.

This invention concerns a coordination complex and salts and optically resolved enantiomers thereof, of the formula (R) 3 --M, wherein R comprises 1,10-phenanthroline or a substituted derivative thereof, M comprises a suitable transition metal, e.g. ruthenium(II), RHODIUM(III) or cobalt(III), and R is bonded to M by a coordination bond. The complexes of this invention are useful in methods for labeling, nicking and cleaving DNA. The lambda enantiomer of complexes of this invention is useful in methods for specifically labeling, detecting, nicking and cleaving Z-DNA or A-DNA. The complexes may also be used in a method for killing tumor cells and may be combined with a pharmaceutically acceptable carrier to form a pharmaceutical composition for the treatment of tumor cells in a subject. The invention further concerns methods for treating a subject affilicted with tumor cells.

Chemical probes for left-handed DNA and for A-DNA; chiral metal complexes as Z-specific antitumor agents and as double strand cleavers

Our recent paper describes the rR spectra of Ru(phen)_2dppz^(2+), Ru(phen)_2(F_2-dppz)^(2+), and Os(phen)_2(dppz)^(2+) (phen = 1,10-phenanthroline, dppz = dipyrido[3,2-a:2‘,3‘-d]phenazine, F_2-dppz = 7,8-difluoro-dppz) obtained utilizing 354.7 nm excitation (fwhm ∼ 10 ns). The spectra collected for Ru(phen)_2(F_2-dppz)^(2+) and Os(phen)_2(dppz)^(2+) were assigned to the ground state of the complexes at both high and low pulse energies. In the case of Ru(phen)_2dppz^(2+), the power dependence of the peaks at 1365 and 1453 cm^(-1) were consistent with an excited state. Our interpretation described below and on the recent paper was not based on the assumption that the ^3ππ* state of the dppz ligand lies below the MLCT in Ru(phen)_2dppz^(2+), but rather that pumping directly into the dppz ^1ππ* manifold could lead to trapping of the excitation at short time scales on the lowest LC dppz state (^3ππ*) if crossing to the MLCT required activation. Lowering of the MLCT relative to the ^3ππ* in Ru(phen)_2(F_2-dppz)^(2+) and Os(phen)_2(dppz)^(2+) would result in lowering the activation barrier and much faster crossing to the MLCT.

Reply to the Comment on “Resonance Raman Investigation of Ru(phen)2dppz2+ and Related Complexes in Water and in the Presence of DNA”

The design of small complexes that bind and react at specific sequences of DNA becomes important as we begin to delineate, on a molecular level, how genetic information is expressed. A more complete understanding of how to target DNA sites with specificity will lead not only to novel chemotherapeutics but also to a greatly expanded ability for chemists to probe DNA and to develop highly sensitive diagnostic agents.

Recognition and Reaction of Metallointercalators with DNA

The disclosed subject matter provides a techniques for precisely and/or functionally cutting carbon nanotubes, e.g., single walled carbon nanotubes (“SWNTs”) and integrating a single nucleic acid molecule (e.g., a DNA molecule) into a gap formed into the carbon nanotubes. In one aspect, a method of fabricating a molecular electronic device includes disposing a SWNT on a base layer, forming a gap in the SWNT using a lithographic process, and disposing a single DNA strand across the gap so that each end of the nucleic acid contacts a gap termini. The disclosed subject matter also provides techniques for measuring the electrical properties (charge transport) of a DNA molecule which is integrated into an SWNT. Furthermore, a molecular electronic device including an SWNT with an integrated nucleic acid molecule is disclosed.

Jacqueline K. Barton

Papers

Chemical probes for left-handed DNA and for A-DNA; chiral metal complexes as Z-specific antitumor agents and as double strand cleavers

Reply to the Comment on “Resonance Raman Investigation of Ru(phen)2dppz2+ and Related Complexes in Water and in the Presence of DNA”

Recognition and Reaction of Metallointercalators with DNA

Systems And Methods For Integrating A Single DNA Molecule Into A Molecular Electronic Device

Protein site recognition by chromium(III) complexes probed through NOE quenching