Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Study Improves Understanding of Surface Molecules in Controlling Size of Gold Nanoparticles

The bulkier the ligand, the fewer ligands can sit side-by-side -- leading to a smaller nanoparticle.
The bulkier the ligand, the fewer ligands can sit side-by-side -- leading to a smaller nanoparticle.

Abstract:
Use of bulky ligands (BLs) in the synthesis of metal nanoparticles (NPs) gives smaller core sizes, sharpens the size distribution, and alters the discrete sizes. For BLs, the highly curved surface of small NPs may facilitate growth, but as the size increases and the surface flattens, NP growth may terminate when the ligand monolayer blocks BLs from transporting metal atoms to the NP core. Batches of thiolate-stabilized Au NPs were synthesized using equimolar amounts of 1-adamantanethiol (AdSH), cyclohexanethiol (CySH), or n-hexanethiol (C6SH). The bulky CyS- and AdS-stabilized NPs have smaller, more monodisperse sizes than the C6S-stabilized NPs. As the bulkiness increases, the near-infrared luminescence intensity increases, which is characteristic of small Au NPs. Four new discrete sizes were measured by MALDI-TOF mass spectrometry, Au30(SAd)18, Au39(SAd)23, Au65(SCy)30, and Au67(SCy)30. No Au25(SAd)18 was observed, which suggests that this structure would be too sterically crowded. Use of BLs may also lead to the discovery of new discrete sizes in other systems.

Study Improves Understanding of Surface Molecules in Controlling Size of Gold Nanoparticles

Raleigh, NC | Posted on June 18th, 2012

North Carolina State University researchers have shown that the "bulkiness" of molecules commonly used in the creation of gold nanoparticles actually dictates the size of the nanoparticles - with larger so-called ligands resulting in smaller nanoparticles. The research team also found that each type of ligand produces nanoparticles in a particular array of discrete sizes.

"This work advances our understanding of nanoparticle formation, and gives us a new tool for controlling the size and characteristics of gold nanoparticles," says Dr. Joseph Tracy, an assistant professor of materials science and engineering at NC State and co-author of a paper describing the research. Gold nanoparticles are used in industrial chemical processes, as well as medical and electronics applications.

When creating gold nanoparticles, scientists often use organic molecules called ligands to facilitate the process. The ligands effectively bring gold atoms together in a solution to create the nanoparticles. In the process, ligands essentially line up side by side and surround the nanoparticles in all three dimensions.

The researchers wanted to see whether the bulkiness of the ligands affected nanoparticle size, and opted to assess three types of thiol ligands - a family of ligands commonly used to synthesize gold nanoparticles. Specifically, the molecules bound to the gold nanoparticles are linear hexanethiolate (-SC6), cyclohexanethiolate (-SCy) and 1-adamantanethiolate (-SAd). Each of these ligands has a bulkier configuration than the last.

For example, picture each ligand as a slice of pie, with a gold atom attached to the pointed end. -SC6 looks like a very narrow slice of pie. -SCy is slightly larger, and -SAd is the largest of the three - with the "crust" end of the pie wedge far wider than the pointed end.

The researchers found that the bulkiness of the ligands determined the size of the nanoparticles. Because fewer -SAd and -SCy ligands can line up next to each other in three dimensions, fewer gold atoms are brought together in the core. Therefore, the nanoparticles are smaller. -SC6, the least bulky of the thiolates, can create the largest nanoparticles.

"While we've shown that this is an effective means of controlling size in gold nanoparticles, we think it may have implications for other materials as well," says Peter Krommenhoek, a Ph.D. student at NC State and lead author of the paper. "That's something we're exploring."

But the researchers made another interesting finding as well.

When particularly small nanoparticles form, they tend to form at very specific sizes, called discrete sizes. For instance, some types of nanoparticles may consist of 25 or 28 atoms - but never 26 or 27 atoms.

In this study, the researchers found that the bulkiness of the ligands also changed the discrete sizes of the nanoparticles. "This is interesting, in part, because each discrete size represents a different number of gold atoms and ligands," Tracy says, "which could influence the nanoparticle's chemical behavior. That question has yet to be addressed."

The paper, "Bulky Adamantanethiolate and Cyclohexanethiolate Ligands Favor Smaller Gold Nanoparticles with Altered Discrete Sizes," was published online June 15 in ACS Nano. The paper was co-authored by Dr. Junwei Wang, a former postdoctoral research associate at NC State; Dr. Nathaniel Hentz, of the Golden LEAF Biomanufacturing Training and Education Center at NC State; Krystian Kozek, a former undergraduate at NC State; Dr. Aaron Johnston-Peck, a postdoctoral researcher at Brookhaven National Laboratory; and Dr. Gregory Kalyuzhny of San Diego State University.

The research was supported by the National Science Foundation and the U.S. Department of Education.

####

For more information, please click here

Contacts:
Matt Shipman
News Services
919.515.6386


Dr. Joe Tracy
919.513.2623

Copyright © North Carolina State University

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

Download paper - “Bulky Adamantanethiolate and Cyclohexanethiolate Ligands Favor Smaller Gold Nanoparticles with Altered Discrete Sizes.”

Related News Press

News and information

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

“Cysteine Rose” Wins 2016 Thermo Fisher Scientific Electron Microscopy Image Contest: Thermo Fisher honors Andrea Jacassi of the Italian Institute of Technology for image of cysteine crystals using focused ion beam techniques March 27th, 2017

Leti and HORIBA Scientific to Host Webinar on Ultrafast Characterization Tool: Plasma Profiling Time-of-Flight Mass Spectrometer Tool Cuts Optimization Time In Layer Deposition and Fabrication of Wide Range of Applications March 27th, 2017

Laser activated gold pyramids could deliver drugs, DNA into cells without harm: Microstructures create temporary pores in cells March 27th, 2017

Chemistry

Promising results obtained with a new electrocatalyst that reduces the need for platinum: Researchers from Aalto University have succeeded in manufacturing electrocatalysts used for storing electric energy with one-hundredth of the amount of platinum that is usually needed March 24th, 2017

Researchers develop groundbreaking process for creating ultra-selective separation membranes: Discovery could greatly improve energy-efficiency of separation and purification processes in the chemical and petrochemical industries March 15th, 2017

Optical fingerprint can reveal pollutants in the air: Researchers at Chalmers University of Technology have proposed a new, sophisticated method of detecting molecules with sensors based on ultra-thin nanomaterials March 15th, 2017

Triboelectric Nanogenerators Boost Mass Spectrometry Performance March 1st, 2017

Govt.-Legislation/Regulation/Funding/Policy

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

Laser activated gold pyramids could deliver drugs, DNA into cells without harm: Microstructures create temporary pores in cells March 27th, 2017

Cryo-electron microscopy achieves unprecedented resolution using new computational methods March 25th, 2017

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Chip Technology

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

ATTOPSEMI Technology Joins FDXcelerator Program to Deliver Advanced Non-Volatile Memory IP to GLOBALFOUNDRIES 22 FDX® Technology Platform: Leading-edge I-fuse™ brings higher reliability, smaller cell size and ease of programmability for consumer, automotive, and IoT applications March 27th, 2017

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Scientists discover new 'boat' form of promising semiconductor: GeSe Uncommon form attenuates semiconductor's band gap size March 23rd, 2017

Nanomedicine

Laser activated gold pyramids could deliver drugs, DNA into cells without harm: Microstructures create temporary pores in cells March 27th, 2017

Researchers make flexible glass for tiny medical devices: Glass can bend over and over again on a nanoscale March 27th, 2017

Cryo-electron microscopy achieves unprecedented resolution using new computational methods March 25th, 2017

Nanobiotix: The Independent Data Monitoring Committee Recommends the Continuation of the Ongoing Phase II/III Trial of NBTXR3 in Soft Tissue Sarcoma March 23rd, 2017

Discoveries

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

Laser activated gold pyramids could deliver drugs, DNA into cells without harm: Microstructures create temporary pores in cells March 27th, 2017

Researchers make flexible glass for tiny medical devices: Glass can bend over and over again on a nanoscale March 27th, 2017

Cryo-electron microscopy achieves unprecedented resolution using new computational methods March 25th, 2017

Announcements

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

“Cysteine Rose” Wins 2016 Thermo Fisher Scientific Electron Microscopy Image Contest: Thermo Fisher honors Andrea Jacassi of the Italian Institute of Technology for image of cysteine crystals using focused ion beam techniques March 27th, 2017

ATTOPSEMI Technology Joins FDXcelerator Program to Deliver Advanced Non-Volatile Memory IP to GLOBALFOUNDRIES 22 FDX® Technology Platform: Leading-edge I-fuse™ brings higher reliability, smaller cell size and ease of programmability for consumer, automotive, and IoT applications March 27th, 2017

Leti and HORIBA Scientific to Host Webinar on Ultrafast Characterization Tool: Plasma Profiling Time-of-Flight Mass Spectrometer Tool Cuts Optimization Time In Layer Deposition and Fabrication of Wide Range of Applications March 27th, 2017

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