/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

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

Monodisperse samples of silver nanocubes were synthesized in large quantities by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP). These cubes were single crystals and were characterized by a slightly truncated shape bounded by {100}, {110}, and {111} facets. The presence of PVP and its molar ratio (in terms of repeating unit) relative to silver nitrate both played important roles in determining the geometric shape and size of the product. The silver cubes could serve as sacrificial templates to generate single-crystalline nanoboxes of gold: hollow polyhedra bounded by six {100} and eight {111} facets. Controlling the size, shape, and structure of metal nanoparticles is technologically important because of the strong correlation between these parameters and optical, electrical, and catalytic properties.

http://science.sciencemag.org/content/sci/298/5601/2176.full.pdf

Shape-Controlled Synthesis of Gold and Silver Nanoparticles

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?

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.

/pdf/nanostructures-in-biodiagnostics-5553cs9yqw.pdf

Nanostructures in Biodiagnostics

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

We synthesized multimetal microrods intrinsically encoded with submicrometer stripes. Complex striping patterns are readily prepared by sequential electrochemical deposition of metal ions into templates with uniformly sized pores. The differential reflectivity of adjacent stripes enables identification of the striping patterns by conventional light microscopy. This readout mechanism does not interfere with the use of fluorescence for detection of analytes bound to particles by affinity capture, as demonstrated by DNA and protein bioassays.

https://science.sciencemag.org/content/sci/294/5540/137.full.pdf

Submicrometer metallic barcodes.

±COOAr, m to ±CH2O±, m to ArCOO± and m to ±OOCAr), 7.25±7.32 (m, 4 Ar±H, o to ±CH2O± and o to ArCOO±), 6.96±7.04 (m, 4 Ar±H, o to ±OCH2(CH2)11± and o to ±OOCAr), 4.20 (t, 2H, ArOCH2CH2O±), 4.05 (t, 2 H, ArOCH2(CH2)10±, J=6.6 Hz), 3.54±4.00 (m, 68 H, ±CH2O±), 3.37 (s, 3 H, CH3O±), 1.77±1.85 (m, 2 H, ±CH2(CH2)9±), 1.14±1.47 (m, 18 H, ±CH2(CH2)9±), 0.87 (t, 3 H, CH3(CH2)11±, J=6.8 Hz). C-NMR (62.5 MHz, CDCl3) d 165.6, 165.4 164.0, 159.6, 151.0, 150.9, 146.4, 138.7, 138.4, 132.7, 131.2, 128.8, 128.6, 128.5, 127.9, 127.1, 122.6, 122.5, 121.9, 115.5, 114.7, 72.3, 71.3, 71.1, 71.0, 68.8, 68.0, 59.4, 32.3, 30.04, 29.99, 29.97, 29.8, 29.5, 26.4, 23.7, 23.1, 14.5: Anal. calcd for C79H116O23: C, 66.18; H, 8.15. Found: C, 66.72, H, 8.33. MW/Mn=1.03 (gel permeation chromatography).

Orthogonal Self‐Assembly on Colloidal Gold‐Platinum Nanorods

branes. The tubes are well ordered but somewhat tilted due to their relatively low mechanical strength compared with cylinders. The Raman spectra of the tubes have shown two broad peaks centered on 1345 and 1565 cm ‐1 , indicating that the tubes consist mainly of DLC. All the nanotubes have a uniform outer diameter of about 300 nm. The wall thickness of the tubes is very small, which can be controlled by optimizing the growth conditions. The tube length was about 7 lm, as in the case of cylinders. All the tubes have uniform height and are found to be hollow inside. Such nanotube arrays are probably useful for field emitters as well as for depositing metal catalysts or enzymes in the tubes, which in turn may be useful for new technologies. Other applications presumably include their use as porous electrodes in electrochemistry, as conductive diamond is known to exhibit outstanding electrochemical properties such as low background current, wide electrochemical potential window and high resistance to deactivation. [19] The present technique is a simple one for producing highly ordered diamond nanocylinders and nanotubes in high yield. The dimensions of these nanofibers are easily controllable by varying the pore dimensions of the alumina membrane. This technique enables others to adopt it easily and study the physical properties of these arrays for various applications in fieldemission displays, photonic bandgap materials, composite materials, and electrochemistry.

DNA‐Directed Assembly of Gold Nanowires on Complementary Surfaces

The effect of colloidal Au nanoparticle immobilization on surface plasmon resonance (SPR) reflectivity is reported. Immobilization of 25 nm diameter colloidal Au on to an evaporated Au film results in a large shift in plasmon angle, a broadened plasmon resonance and an increase in minimum reflectance. This results in increased SPR sensitivity, demonstrated in several ways, including a sandwich immunoassay for human IgG, enlargement of a 1.4 nm diameter Au cluster, and detection of displacement of surface-bound biotinylated colloidal Au by free biocytin in solution. Similarly large changes in reflectivity are realized upon binding of colloidal Au to electrolessly deposited Au films prepared entirely by wet-chemical methods. These results represent potentially significant advances in the generality and sensitivity of SPR.

Brian D. Reiss

Papers

Submicrometer metallic barcodes.

Orthogonal Self‐Assembly on Colloidal Gold‐Platinum Nanorods

DNA‐Directed Assembly of Gold Nanowires on Complementary Surfaces

Surface plasmon resonance of colloidal Au-modified gold films

Electrochemical synthesis and optical readout of striped metal rods with submicron features