Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Novel nanocrystals with advanced optical properties developed for use as luminescent biomarkers

Abstract:
Researchers from Singapore, Saudi Arabia and China develop a synthesis that yields lanthanide-doped nanocrystals with advanced light-control properties, leading to potential applications in cancer diagnostics, medical imaging and therapeutic delivery.

Novel nanocrystals with advanced optical properties developed for use as luminescent biomarkers

Singapore | Posted on November 14th, 2011

Upconversion emission materials are ideal for bioimaging due to its effectiveness as contrast agents for the detection of cancer cells, more so when the background emission of non-cancerous tissues can be minimised. These materials could be used as biomarkers for luminescent labeling of cancerous cells. Opaque tissues can be turned into glassy, transparent substances by using these biomarkers which rely on near-infrared excitation.

The Singapore research team led by Associate Professor Xiaogang Liu and its co-researchers from Saudi Arabia and China succeeded in developing an efficient upconversion process in nanoparticles, ensuring a broad tunability of light emission that could be used in imaging applications. They found a chemical structure that can exhibit efficient upconversion properties through a special arrangement of energy levels. Their synthesis of lanthanide-doped core-shell nanocrystals which resulted in advanced optical properties that can control light, proved to be a novel approach.

For sensing applications, separating optical signals from the background can be tricky when the signal and noise occur at the same wavelength. This problem can be solved with upconversion - a nonlinear optical process - where two low-energy photons of an incident beam can be converted into a single photon of higher energy, which can then be easily distinguished from the background.

The ability to convert light using these nanomaterials for heating also offers promising applications in photodynamic therapy and drug delivery.

The work of Assoc Prof Liu and team was reported in the Nature Materials journal, one of the best known materials research-related journals in the world, on 23 October 2011. His team comprises research fellow Dr Feng Wang and graduate students Renren Deng and Juan Wang from the National University of Singapore's (NUS) Department of Chemistry. They worked alongside researchers from King Abdullah University of Science and Technology and Fujian Institute of Research on the Structure of Matter. Assoc Prof Liu and Dr Feng Wang are also scientists at the Institute of Materials Research and Engineering (IMRE), a research institute of Singapore's Agency for Science, Technology and Research (A*STAR).

The published research work was funded by Singapore's A*STAR and Ministry of Education.

A novel approach to cancer detection

The team of researchers focuses on controlling the optical properties of nanomaterials by doping rare-earth metals in confined layer-by-layer structures. The nanoparticle shell can be doped with different rare earth metals, resulting in a broad tunability of the upconverted emission.

By producing nanoparticles with tunable emission which should also have a low toxicity, the researchers have made a great leap in the development of upconverting materials.

Their novel approach involves the designing of core-shell nanoparticles that separates the upconversion process from that of light emission. Photons are absorbed in the core of the nanoparticles and turned into excited electrons, after which they cascade from the core of the nanoparticles into the excited state of rare earth dopants in the shell. While there, these electrons relax and emit light.

Although such sequential energy transfer has been investigated for certain semiconductor nanoparticles and nanowires for solar energy applications, it has not been done so before for rare earth-doped nanoparticles.

Assoc Prof Liu pointed out that effort to find upconverting ions that emit in a wide-ranging spectral region has been unsuccessful until now. This is because an efficient photon upconversion has generally been restricted to a small number of lanthanide ions with emitted light signal detectable by the naked eye.

Explaining his successful approach, Assoc Prof Liu said: "We perform photon upconversion on an array of rare-earth metals. Photon upconversion turns low energy near-infrared light into higher energy made visible with the rational design and chemical synthesis of a core-shell nanostructure."

Assoc Prof Liu and team prepared nanoparticles which could demonstrate an upconversion emission ranging from violet, blue, green to red yellow, with significantly longer infrared excitation wavelengths of up to 980 nm. An important aspect of using light with 980 nm wavelength is such that the transparency of living tissues is high in infrared. This enhances the opportunity for the use of these nanoparticles for cancer detection. Furthermore, the multiple emission colours demonstrated in this research can potentially be used for a more reliable biological diagnostics application, for instance, multiple cell markers.

Opportunities for wider use

The ability to convert low energy near-infrared light into higher energy visible emission, along with low levels of toxicity to cells, and ease of processing, will turn nanometer-sized lanthanide-doped crystals into ideal materials for numerous applications.

According to the group from NUS, the results indicate that a large "library" of luminescent upconversion nanocrystals with distinguishable spectroscopic fingerprints can now be established. When coupled with biological molecules, these nanomaterials would provide a platform for a rapid and reliable route to multiplex detection of cancer or other diseases. The ability of these nanomaterials to induce light-control release of drugs for site-specific delivery also bodes well for future medicine - fewer or reduced side effects can be expected as lanthanide-doped crystals have been tested to be non toxic.

"This work made me confident that we will see exciting new applications for these particles soon," says Thomas Nann, a research professor from the University of South Australia whose research is in this same field. Prof Nann adds that "Up-converting nanoparticles are materials with a tremendous potential for application. However, due to the need for a rigorous selection of usable up-converting ions, Science appeared not to have made any headway for some time prior to this discovery."

Assoc Prof Liu and co-researchers noted the uniqueness of their design, which is the use of core-shell nanostructures and gadolinium ions for energy migration that enhances the ability to produce a wide range of lanthanide-doped nanocrystals to yield upconverted luminescence.

"Benefiting from the sub-lattice of gadolinium ions as a network for energy migration, these judiciously-designed nanoparticles light up those less commonly used lanthanide ions like terbium, europium, and samarium under near-infrared excitation," explains Professor Chun-Hua Yan, a chemistry professor and well known scientist in the same field in Peking University, China. Adding, Prof Yan says "I do believe that this model, with its uniqueness and versatility, will vastly enrich the currently available upconversion materials, and will have impact on relevant fields such as luminescent biolabelling, multiplexed data storage and display."

The Singapore group has recently filed a related patent for their ground-breaking discovery. Currently, they are working with clinicians to develop clinical diagnostic models for use in a practical manner.

####

About National University of Singapore
A leading global university centred in Asia, the National University of Singapore (NUS) is Singapore's flagship university which offers a global approach to education and research, with a focus on Asian perspectives and expertise.

NUS has 16 faculties and schools across three campuses. Its transformative education includes a broad-based curriculum underscored by multi-disciplinary courses and cross-faculty enrichment. Over 36,000 students from 100 countries enrich the community with their diverse social and cultural perspectives.

NUS has three Research Centres of Excellence (RCE) and 21 university-level research institutes and centres. It is also a partner in Singapore's 5th RCE. NUS shares a close affiliation with 16 national-level research institutes and centres. Research activities are strategic and robust, and NUS is well-known for its research strengths in engineering, life sciences and biomedicine, social sciences and natural sciences. It also strives to create a supportive and innovative environment to promote creative enterprise within its community.

For more information, please visit www.nus.edu.sg.

About the Institute of Materials Research and Engineering (IMRE)

The Institute of Materials Research and Engineering (IMRE) is a research institute of the Agency for Science, Technology and Research (A*STAR). The Institute has capabilities in materials analysis & characterisation, design & growth, patterning & fabrication, and synthesis & integration. We house a range of state-of-the-art equipment for materials research including development, processing and characterisation. IMRE conducts a wide range of research, which includes novel materials for organic solar cells, photovoltaics, printed electronics, catalysis, bio-mimetics, microfluidics, quantum dots, heterostructures, sustainable materials, atom technology, etc. We collaborate actively with other research institutes, universities, public bodies, and a wide spectrum of industrial companies, both globally and locally.

For more information about IMRE, please visit www.imre.a-star.edu.sg.

For more information, please click here

Contacts:
Swee Kang Ng

65-651-65125

Mr Eugene LOW
Manager, Corporate Communications
Institute of Materials Research and Engineering (IMRE)
Tel: (65) 6874 8491
Mobile: (65) 9230 9235

Copyright © National University of Singapore

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

'Energy migration upconversion in lanthanide-doped core-shell nanocrystals' by Feng Wang, Renren Deng, Juan Wang, Qingxiao Wang, Yu Han, Haomiao Zhu, Xueyuan Chen & Xiaogang Liu was published online on 23 October 2011 in Nature Materials and is available at www.nature.com/nmat (DOI: 10.1038/NMAT3149).

Related News Press

News and information

Stanford team achieves 'holy grail' of battery design: A stable lithium anode - Engineers use carbon nanospheres to protect lithium from the reactive and expansive problems that have restricted its use as an anode July 27th, 2014

Iranian Scientists Produce Reusable Nanoadsorbent to Detect Sulfamide in Chicken July 27th, 2014

Breakthrough laser experiment reveals liquid-like motion of atoms in an ultra-cold cluster: University of Leicester research team unlocks insights into creation of new nano-materials July 25th, 2014

Scientists Test Nanoparticle "Alarm Clock" to Awaken Immune Systems Put to Sleep by Cancer July 25th, 2014

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

Imaging

New imaging agent provides better picture of the gut July 25th, 2014

Nanomedicine

New imaging agent provides better picture of the gut July 25th, 2014

Scientists Test Nanoparticle "Alarm Clock" to Awaken Immune Systems Put to Sleep by Cancer July 25th, 2014

Researchers create vaccine for dust-mite allergies Main Page Content: Vaccine reduced lung inflammation to allergens in lab and animal tests July 22nd, 2014

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

Discoveries

Stanford team achieves 'holy grail' of battery design: A stable lithium anode - Engineers use carbon nanospheres to protect lithium from the reactive and expansive problems that have restricted its use as an anode July 27th, 2014

Iranian Scientists Produce Reusable Nanoadsorbent to Detect Sulfamide in Chicken July 27th, 2014

New imaging agent provides better picture of the gut July 25th, 2014

Breakthrough laser experiment reveals liquid-like motion of atoms in an ultra-cold cluster: University of Leicester research team unlocks insights into creation of new nano-materials July 25th, 2014

Announcements

Stanford team achieves 'holy grail' of battery design: A stable lithium anode - Engineers use carbon nanospheres to protect lithium from the reactive and expansive problems that have restricted its use as an anode July 27th, 2014

Iranian Scientists Produce Reusable Nanoadsorbent to Detect Sulfamide in Chicken July 27th, 2014

Breakthrough laser experiment reveals liquid-like motion of atoms in an ultra-cold cluster: University of Leicester research team unlocks insights into creation of new nano-materials July 25th, 2014

Scientists Test Nanoparticle "Alarm Clock" to Awaken Immune Systems Put to Sleep by Cancer July 25th, 2014

Photonics/Optics/Lasers

NUS scientists use low cost technique to improve properties and functions of nanomaterials: By 'drawing' micropatterns on nanomaterials using a focused laser beam, scientists could modify properties of nanomaterials for effective applications in photonic and optoelectric applicat July 22nd, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Future Electronics May Depend on Lasers, Not Quartz July 17th, 2014

Research partnerships

Breakthrough laser experiment reveals liquid-like motion of atoms in an ultra-cold cluster: University of Leicester research team unlocks insights into creation of new nano-materials July 25th, 2014

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE