Multiplexed detection of oligonucleotide targets has been performed with gold nanoparticle probes labeled with oligonucleotides and Raman-active dyes. The gold nanoparticles facilitate the formation of a silver coating that acts as a surface-enhanced Raman scattering promoter for the dye-labeled particles that have been captured by target molecules and an underlying chip in microarray format. The strategy provides the high-sensitivity and high-selectivity attributes of gray-scale scanometric detection but adds multiplexing and ratioing capabilities because a very large number of probes can be designed based on the concept of using a Raman tag as a narrow-band spectroscopic fingerprint. Six dissimilar DNA targets with six Raman-labeled nanoparticle probes were distinguished, as well as two RNA targets with single nucleotide polymorphisms. The current unoptimized detection limit of this method is 20 femtomolar.

https://science.sciencemag.org/content/sci/297/5586/1536.full.pdf

Nanoparticles with Raman Spectroscopic Fingerprints for DNA and RNA Detection

The development of novel materials is a fundamental focal point of chemical research; and this interest is mandated by advancements in all areas of industry and technology. A good example of the synergism between scientific discovery and technological development is the electronics industry, where discoveries of new semiconducting materials resulted in the evolution from vacuum tubes to diodes and transistors, and eventually to miniature chips. The progression of this technology led to the development * To whom correspondence should be addressed. B.L.C.: (504) 2801385 (phone); (504) 280-3185 (fax); bcushing@uno.edu (e-mail). C.J.O.: (504)280-6846(phone);(504)280-3185(fax);coconnor@uno.edu (e-mail). 3893 Chem. Rev. 2004, 104, 3893−3946

http://depa.fquim.unam.mx/amyd//archivero/FidelmarLechugaSanabria_4940.pdf

Recent advances in the liquid-phase syntheses of inorganic nanoparticles.

In the mid-1970s, surface-enhanced Raman scattering (SERS) was discovered which impacted on surface science and spectroscopy because of its extremely high surface sensitivity. However, SERS had not developed as many people had hoped to be a powerful surface diagnostic technique that can be widely used because of some obstacles. For example, only three noble metals Au, Ag, and Cu could provide large enhancement, severely limiting the widespread applications involving other metallic materials of both fundamental and practical importance. In this article, emphasis is put on the recent work of our group to directly generate SERS on net transition metals (e.g., Pt, Ru, Rh, Pd, Fe, Co, Ni, and their alloys) by developing various roughening procedures and optimizing the performance of the confocal Raman microscope. An approach of replacing the randomly roughened surface with ordered nanorod arrays of transition metals is introduced as a promising class of highly SERS-active substrates. The surface enhancement fa...

Surface-Enhanced Raman Scattering: From Noble to Transition Metals and from Rough Surfaces to Ordered Nanostructures

Nanoparticles can display four unique advantages over macroelectrodes when used for electroanalysis: enhancement of mass transport, catalysis, high effective surface area and control over electrode microenvironment. Therefore, much work has been carried out into their formation, characterisation and employment for the detection of many electroactive species. This paper aims to give an overview of the investigations carried out in this field. Particular attention is paid to examples of the advantages and disadvantages nanoparticles show when compared to macroelectrodes and the advantages of one nanoparticle modification over another. Most work has been carried out using gold, silver and platinum metals. However, iron, nickel and copper are also reviewed with some examples of other metals such as iridium, ruthenium, cobalt, chromium and palladium. Some bimetallic nanoparticle modifications are also mentioned because they can cause unique catalysis through the mixing of the properties of both metals.

The use of nanoparticles in electroanalysis: a review

Self-assembled multilayer thin films consisting of alternating layers of ∼6-nm Au nanoparticles and α,ω-dithiols have been prepared on glass substrates. They have been studied by UV/Vis spectroscopy, ellipsometry, scanning tunneling microscopy, and temperature-dependent conductivity measurements. The electronic and optical properties of the thin film material are nonmetallic, and the Au particles maintain their individual character without fusion to larger units. Electronic conduction within the films occurs via activated electron hopping.

Self-Assembled Gold Nanoparticle Thin Films with Nonmetallic Optical and Electronic Properties

Very highly conductive Au films on glass substrates have been prepared by stepwise, layer-by-layer immobilization of 11-nm diameter colloidal Au particles and a short organic cross-linker Particle

Stepwise Construction of Conductive Au Colloid Multilayers from Solution

This paper describes three closely related experiments utilizing colloidal Au nanoparticles to teach basic concepts in physical chemistry This is done in the context of surface chemistry and nanomaterials synthesis, areas of intense current research interest in both academics and industry First, students investigate the optical properties and stability of aqueous Au colloidal suspensions, determining the amount of a protein (protein A) necessary to prevent salt-induced flocculation of colloidal Au Then, the kinetics of Au nanoparticle surface immobilization on silanized glass slides is followed by visible spectrophotometry Data are fit to a (time)1/2 curve that describes particle diffusion and adsorption from an unstirred solution onto a planar substrate Finally, the adsorption isotherm data are fit to a Frumkin isotherm, demonstrating the effects of interparticle repulsions upon the thermodynamics of Au particle monolayer formation Each experiment benefits from the intense visible absorption of col

Kinetics and Thermodynamics of Au Colloid Monolayer Self-Assembly: Undergraduate Experiments in Surface and Nanomaterials Chemistry

Methods for the preparation of novel metal nanoparticle and glass composites are disclosed. The composites themselves are also disclosed. In particular, a method for the preparation of colloidal metal nanoparticles imbedded in a glass surface is disclosed. Further disclosed is a method for making an array of zeptoliter vials by preparing a composite of colloidal metal nanoparticles imbedded in a glass surface, and dissolving the colloidal metal nanoparticles.

Melinda H. Keefe

Papers

Stepwise Construction of Conductive Au Colloid Multilayers from Solution

Kinetics and Thermodynamics of Au Colloid Monolayer Self-Assembly: Undergraduate Experiments in Surface and Nanomaterials Chemistry

Thermal immobilization of colloidal metal nanoparticles