Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > Carrying and releasing nanoscale cargo with 'nanowrappers': Nanocubes with hollow interiors and surface openings whose shape, size, and location are precisely controlled could be used to load and unload materials for biomedical, catalysis, and optical sensing applications

The 3-D structure and chemical composition characterizations of the products obtained after five minutes (a), 20 minutes (b), and one hour (c). The scanning electron microscope images (subscript 1, scale bars are 100 nanometers), reconstructed 3-D volume renderings (subscript 2), and 3-D elemental mappings (subscript 3, gold in green and silver in red) show the transformation of the silver nanocubes into gold-silver nanowrappers.

CREDIT
Brookhaven National Laboratory
The 3-D structure and chemical composition characterizations of the products obtained after five minutes (a), 20 minutes (b), and one hour (c). The scanning electron microscope images (subscript 1, scale bars are 100 nanometers), reconstructed 3-D volume renderings (subscript 2), and 3-D elemental mappings (subscript 3, gold in green and silver in red) show the transformation of the silver nanocubes into gold-silver nanowrappers. CREDIT Brookhaven National Laboratory

Abstract:
This holiday season, scientists at the Center for Functional Nanomaterials (CFN)--a U.S. Department of Energy Office of Science User Facility at Brookhaven National Laboratory--have wrapped a box of a different kind. Using a one-step chemical synthesis method, they engineered hollow metallic nanosized boxes with cube-shaped pores at the corners and demonstrated how these "nanowrappers" can be used to carry and release DNA-coated nanoparticles in a controlled way. The research is reported in a paper published on Dec. 12 in ACS Central Science, a journal of the American Chemical Society (ACS).

Carrying and releasing nanoscale cargo with 'nanowrappers': Nanocubes with hollow interiors and surface openings whose shape, size, and location are precisely controlled could be used to load and unload materials for biomedical, catalysis, and optical sensing applications

Upton, NY | Posted on January 3rd, 2019

"Imagine you have a box but you can only use the outside and not the inside," said co-author Oleg Gang, leader of the CFN Soft and Bio Nanomaterials Group. "This is how we've been dealing with nanoparticles. Most nanoparticle assembly or synthesis methods produce solid nanostructures. We need methods to engineer the internal space of these structures."

"Compared to their solid counterparts, hollow nanostructures have different optical and chemical properties that we would like to use for biomedical, sensing, and catalytic applications," added corresponding author Fang Lu, a scientist in Gang's group. "In addition, we can introduce surface openings in the hollow structures where materials such as drugs, biological molecules, and even nanoparticles can enter and exit, depending on the surrounding environment."

Synthetic strategies have been developed to produce hollow nanostructures with surface pores, but typically the size, shape, and location of these pores cannot be well-controlled. The pores are randomly distributed across the surface, resulting in a Swiss-cheese-like structure. A high level of control over surface openings is needed in order to use nanostructures in practical applications--for example, to load and release nanocargo.

In this study, the scientists demonstrated a new pathway for chemically sculpturing gold-silver alloy nanowrappers with cube-shaped corner holes from solid nanocube particles. They used a chemical reaction known as nanoscale galvanic replacement. During this reaction, the atoms in a silver nanocube get replaced by gold ions in an aqueous solution at room temperature. The scientists added a molecule (surfactant, or surface-capping agent) to the solution to direct the leaching of silver and the deposition of gold on specific crystalline facets.

"The atoms on the faces of the cube are arranged differently from those in the corners, and thus different atomic planes are exposed, so the galvanic reaction may not proceed the same way in both areas," explained Lu. "The surfactant we chose binds to the silver surface just enough--not too strongly or weakly--so that gold and silver can interact. Additionally, the absorption of surfactant is relatively weak on the silver cube's corners, so the reaction is most active here. The silver gets "eaten" away from its edges, resulting in the formation of corner holes, while gold gets deposited on the rest of the surface to create a gold and silver shell."

To capture the structural and chemical composition changes of the overall structure at the nanoscale in 3-D and at the atomic level in 2-D as the reaction proceeded over three hours, the scientists used electron microscopes at the CFN. The 2-D electron microscope images with energy-dispersive X-ray spectroscopy (EDX) elemental mapping confirmed that the cubes are hollow and composed of a gold-silver alloy. The 3-D images they obtained through electron tomography revealed that these hollow cubes feature large cube-shaped holes at the corners.

"In electron tomography, 2-D images collected at different angles are combined to reconstruct an image of an object in 3-D," said Gang. "The technique is similar to a CT [computerized tomography] scan used to image internal body structures, but it is carried out on a much smaller size scale and uses electrons instead of x-rays."

The scientists also confirmed the transformation of nanocubes to nanowrappers through spectroscopy experiments capturing optical changes. The spectra showed that the optical absorption of the nanowrappers can be tuned depending on the reaction time. At their final state, the nanowrappers absorb infrared light.

"The absorption spectrum showed a peak at 1250 nanometers, one of the longest wavelengths reported for nanoscale gold or silver," said Gang. "Typically, gold and silver nanostructures absorb visible light. However, for various applications, we would like those particles to absorb infrared light--for example, in biomedical applications such as phototherapy."

Using the synthesized nanowrappers, the scientists then demonstrated how spherical gold nanoparticles of an appropriate size that are capped with DNA could be loaded into and released from the corner openings by changing the concentration of salt in the solution. DNA is negatively charged (owing to the oxygen atoms in its phosphate backbone) and changes its configuration in response to increasing or decreasing concentrations of a positively charged ion such as salt. In high salt concentrations, DNA chains contract because their repulsion is reduced by the salt ions. In low salt concentrations, DNA chains stretch because their repulsive forces push them apart.

When the DNA strands contract, the nanoparticles become small enough to fit in the openings and enter the hollow cavity. The nanoparticles can then be locked within the nanowrapper by decreasing the salt concentration. At this lower concentration, the DNA strands stretch, thereby making the nanoparticles too large to go through the pores. The nanoparticles can leave the structure through a reverse process of increasing and decreasing the salt concentration.

"Our electron microscopy and optical spectroscopy studies confirmed that the nanowrappers can be used to load and release nanoscale components," said Lu. "In principle, they could be used to release optically or chemically active nanoparticles in particular environments, potentially by changing other parameters such as pH or temperature."

Going forward, the scientists are interested in assembling the nanowrappers into larger-scale architectures, extending their method to other bimetallic systems, and comparing the internal and external catalytic activity of the nanowrappers.

"We did not expect to see such regular, well-defined holes," said Gang. "Usually, this level of control is quite difficult to achieve for nanoscale objects. Thus, our discovery of this new pathway of nanoscale structure formation is very exciting. The ability to engineer nano-objects with a high level of control is important not only to understanding why certain processes are happening but also to constructing targeted nanostructures for various applications, from nanomedicine and optics to smart materials and catalysis. Our new synthesis method opens up unique opportunities in these areas."

"This work was made possible by the world-class expertise in nanomaterial synthesis and capabilities that exist at the CFN," said CFN Director Charles Black. "In particular, the CFN has a leading program in the synthesis of new materials by assembly of nanoscale components, and state-of-the-art electron microscopy and optical spectroscopy capabilities for studying the 3-D structure of these materials and their interaction with light. All of these characterization capabilities are available to the nanoscience research community through the CFN user program. We look forward to seeing the advances in nano-assembly that emerge as scientists across academia, industry, and government make use of the capabilities in their research."

####

About Brookhaven National Laboratory
Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Follow @BrookhavenLab on Twitter or find us on Facebook.

For more information, please click here

Contacts:
Ariana Tantillo

631-344-2347

Copyright © Brookhaven National Laboratory

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

RELATED JOURNAL ARTICLE:

Related News Press

News and information

Nanometrics to Announce Fourth Quarter and Full Year Financial Results on February 5, 2019 January 18th, 2019

ULVAC Inc., and Oxford Instruments Plasma Technology collaborate to bring Atomic Scale Processing solutions to the Japanese Power and RF markets January 18th, 2019

Kiel physicists discover new effect in the interaction of plasmas with solids January 18th, 2019

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

Chemistry

Chirality in 'real-time' January 14th, 2019

Chemical synthesis of nanotubes: Nanometer-sized tubes made from simple benzene molecules January 11th, 2019

Quantum chemistry on quantum computers: A quantum algorithm for tracking complex chemical reactions with neither performing demanding post-Hartree-Fock calculations nor exponential time explosion January 4th, 2019

Strem Chemicals, Inc., Receives National Performance Improvement Honor: Company Recognized for Stakeholder Communications December 20th, 2018

Laboratories

Revealing hidden spin: Unlocking new paths toward high-temperature superconductors: Berkeley Lab researchers uncover insights into superconductivity, leading potentially to more efficient power transmission January 4th, 2019

New composite advances lignin as a renewable 3D printing material December 28th, 2018

Scientists use magnetic defects to achieve electromagnetic wave breakthrough December 20th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

Nanobiotix Plans to Conduct Registered Public Offering in the United States January 17th, 2019

2D materials may enable electric vehicles to get 500 miles on a single charge January 11th, 2019

Spintronics 'miracle material' put to the test: Physicists build devices using mineral perovskite January 11th, 2019

Possible Futures

Kiel physicists discover new effect in the interaction of plasmas with solids January 18th, 2019

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

Nanobiotix Plans to Conduct Registered Public Offering in the United States January 17th, 2019

Power stations driven by light: More efficient solar cells imitate photosynthesis January 16th, 2019

Nanomedicine

Nanobiotix Plans to Conduct Registered Public Offering in the United States January 17th, 2019

Chirality in 'real-time' January 14th, 2019

Ultra-sensitive sensor with gold nanoparticle array January 9th, 2019

Arrowhead Pharmaceuticals Begins Dosing in Phase 1 Study of ARO-ANG3 for Treatment of Dyslipidemias and Metabolic Diseases January 7th, 2019

Discoveries

Using bacteria to create a water filter that kills bacteria: New technology can clean water twice as fast as commercially available ultrafiltration membranes January 18th, 2019

Kiel physicists discover new effect in the interaction of plasmas with solids January 18th, 2019

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

Light up logic: Engineers from UTokyo and RIKEN perform computational logic with light January 18th, 2019

Materials/Metamaterials

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

Drilling speed increased by 20% yet another upgrade in the oil & gas sector made possible by graphene nanotubes January 15th, 2019

New materials could help improve the performance of perovskite solar cells January 11th, 2019

Spintronics 'miracle material' put to the test: Physicists build devices using mineral perovskite January 11th, 2019

Announcements

Nanometrics to Announce Fourth Quarter and Full Year Financial Results on February 5, 2019 January 18th, 2019

ULVAC Inc., and Oxford Instruments Plasma Technology collaborate to bring Atomic Scale Processing solutions to the Japanese Power and RF markets January 18th, 2019

Kiel physicists discover new effect in the interaction of plasmas with solids January 18th, 2019

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Using bacteria to create a water filter that kills bacteria: New technology can clean water twice as fast as commercially available ultrafiltration membranes January 18th, 2019

Kiel physicists discover new effect in the interaction of plasmas with solids January 18th, 2019

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

New materials could help improve the performance of perovskite solar cells January 11th, 2019

Nanobiotechnology

Using bacteria to create a water filter that kills bacteria: New technology can clean water twice as fast as commercially available ultrafiltration membranes January 18th, 2019

Nanobiotix Plans to Conduct Registered Public Offering in the United States January 17th, 2019

Cartilage could be key to safe 'structural batteries' January 11th, 2019

Ultra-sensitive sensor with gold nanoparticle array January 9th, 2019

Photonics/Optics/Lasers

Brilliant glow of paint-on semiconductors comes from ornate quantum physics January 18th, 2019

Light up logic: Engineers from UTokyo and RIKEN perform computational logic with light January 18th, 2019

Media invited to open meeting on the future of quantum technology held at RIT Jan. 23-25: Leaders from NASA, NSF, NIST and Sandia National Laboratory to attend January 11th, 2019

Nanoscribe Presents Successor Model Photonic Professional GT2 for High-Resolution 3D Microfabrication: The first ever production of structures in millimeter size with micrometer precision December 4th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project