Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study shows nanoshells ideal as chemical nanosensors

12.01.2005


’Nanoshells’ enhance sensitivity to chemical detection by factor of 10 billion



New research published in the Proceedings of the National Academy of Science finds that tailored nanoparticles known as nanoshells can enhance chemical sensing by as much as 10 billion times. That makes them about 10,000 times more effective at Raman scattering than traditional methods.

When molecules and materials scatter light, a small fraction of the light interacts in such a way that it allows scientists to determine their detailed chemical makeup. This property, known as Raman scattering, is used by medical researchers, drug designers, chemists and other scientists to determine what materials are made of. An enormous limitation in the use of Raman scattering has been its extremely weak sensitivity. While it was discovered almost three decades ago that roughened metallic surfaces could enhance Raman scattering signals by factors of 1 million, this "surface-enhancement" effect has been difficult to control, predict, and reproduce for practical sensing applications. Now, Rice researchers have shown that nanoshells can provide large, clean, reproducible enhancements of this effect, opening the door for new, all-optical sensing applications.


"Not only did we find that nanoshells are extremely effective at magnifying the Raman signature of molecules, we found each individual nanoshell acts as an independent Raman enhancer," said lead researcher Naomi Halas, the Stanley C. Moore Professor of Electrical and Computer Engineering, Professor of Chemistry and Director of Rice’s Laboratory of Nanophotonics. "That creates an opportunity to design all-optical nanoscale sensors -- essentially new molecular-level diagnostic instruments -- that could detect as little as a few molecules of a target substance, which could be anything from a drug molecule or a key disease protein to a deadly chemical agent."

About 1/20th the size of a red blood cell, nanoshells are about the size of a virus. They are ball-shaped and consist of a core of non-conducting glass that is covered by a metallic shell, typically either gold or silver. The metal shell "captures" passing light and focuses it, a property that directly leads to the enormous Raman enhancements observed. Furthermore, nanoshells can be "tuned" to interact with specific wavelengths of light by varying the thickness of their shells. This tunability allows for the Raman enhancements to be optimized for specific wavelengths of light.

Discovered by Halas at Rice in the 1990s, nanoshells are already being developed for applications including cancer diagnosis, cancer therapy, diagnosis and testing for proteins associated with Alzheimer’s disease, drug delivery and rapid whole-blood immunoassay.

In the current study, Halas and former graduate student Joseph B. Jackson, now with Nanospectra Biosciences, Inc., created thin films of nanoshells deposited atop plates of glass. Films with various densities were studied, as were films containing both silver and gold nanoshells.

Through painstaking analysis, Halas and Jackson showed that the nanoshells’ 10 billion-fold increase in Raman effect was due entirely to the interactions of light with individual nanoshells. This is markedly different from the pattern exhibited by pure gold or silver nanoparticle films. In that case, the Raman enhancement is an aggregate effect, due to the presence of localized "junctions" or "hot spots" between metallic regions of the metallic film substrate.

The finding that individual nanoshells can vastly enhance the Raman effect opens the door for biosensor designs that use a single nanoshell, something that could prove useful for engineers who are trying to probe the chemical processes within small structures such as individual cells, or for the detection of very small amounts of a material, like a few molecules of a deadly biological or chemical agent.

Jade Boyd | EurekAlert!
Further information:
http://www.rice.edu

More articles from Studies and Analyses:

nachricht Do microplastics harbour additional risks by colonization with harmful bacteria?
05.04.2018 | Leibniz-Institut für Ostseeforschung Warnemünde

nachricht Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

Im Focus: The Future of Ultrafast Solid-State Physics

In an article that appears in the journal “Review of Modern Physics”, researchers at the Laboratory for Attosecond Physics (LAP) assess the current state of the field of ultrafast physics and consider its implications for future technologies.

Physicists can now control light in both time and space with hitherto unimagined precision. This is particularly true for the ability to generate ultrashort...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model

19.04.2018 | Materials Sciences

Electromagnetic wizardry: Wireless power transfer enhanced by backward signal

19.04.2018 | Physics and Astronomy

Ultrafast electron oscillation and dephasing monitored by attosecond light source

19.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>