Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Silver cycle: New evidence for natural synthesis of silver nanoparticles

Transmission electron microscopy (TEM) image of silver nanoparticles formed from silver ions in solution with humic acid. The acid tends to coat the nano particles (visible here as a pale cloud), keeping them in a colloidal suspension instead of clumping together. (Color added for clarity.)

Credit: SUNY, Buffalo
Transmission electron microscopy (TEM) image of silver nanoparticles formed from silver ions in solution with humic acid. The acid tends to coat the nano particles (visible here as a pale cloud), keeping them in a colloidal suspension instead of clumping together. (Color added for clarity.)

Credit: SUNY, Buffalo

Abstract:
Nanoparticles of silver are being found increasingly in the environment—and in environmental science laboratories. Because they have a variety of useful properties, especially as antibacterial and antifungal agents, silver nanoparticles increasingly are being used in a wide variety of industrial and consumer products. This, in turn, has raised concerns about what happens to them once released into the environment. Now a new research paper* adds an additional wrinkle: Nature may be making silver nanoparticles on its own.

Silver cycle: New evidence for natural synthesis of silver nanoparticles

Gaithersburg, MD | Posted on May 11th, 2011

A team of researchers from the Florida Institute of Technology (FIT), the State University of New York (SUNY), Buffalo, and the National Institute of Standards and Technology (NIST) reports that, given a source of silver ions, naturally occurring humic acid will synthesize stable silver nanoparticles.

"Our colleague, Virender Sharma, had read an article in which they were using wine to form nanoparticles. He thought that, based on the similar chemistry, we should be able to produce silver nanoparticles with humic acids," explains FIT chemist Mary Sohn. "First we formed them by traditional methods and then we tried one of our river sediment humic acids. We were really excited that we could see the characteristic yellow color of the nanoparticles." Samples were sent to Sarbajit Banerjee at SUNY Buffalo and Robert MacCuspie at NIST for detailed analyses to confirm the presence of silver nanoparticles.

"Humic acid" is a complex mixture of many organic acids that are formed during the decay of dead organic matter. Although the exact composition varies from place to place and season to season, humic acid is ubiquitous in the environment. Metallic nanoparticles, MacCuspie explains, have characteristic colors that are a direct consequence of their size.** Silver nanoparticles appear a yellowish brown.

The team mixed silver ions with humic acid from a variety of sources at different temperatures and concentrations and found that acids from river water or sediments would form detectable silver nanoparticles at room temperature in as little as two to four days. Moreover, MacCuspie says, the humic acid appears to stabilize the nanoparticles by coating them and preventing the nanoparticles from clumping together into a larger mass of silver. "We believe it's actually a similar process to how nanoparticles are synthesized in the laboratory," he says, except that the lab process typically uses citric acid at elevated temperatures.

"This caught us by surprise because a lot of our work is focused on how silver nanoparticles may dissolve when they're released into the environment and release silver ions," MacCuspie says. Many biologists believe the toxicity of silver nanoparticles, the reason for their use as an antibacterial or antifungal agent, is due to their high surface area that makes them an efficient source of silver ions, he says, but "this creates the idea that there may be some sort of natural cycle returning some of the ions to nanoparticles." It also helps explain the discovery, over the past few years, of silver nanoparticles in locations like old mining regions that are not likely to have been exposed to man-made nanoparticles, but would have significant concentrations of silver ions.

* N. Akaighe, R.I. MacCuspie, D.A. Navarro, D.S. Aga, S. Banerjee, M. Sohn and V.K. Sharma. Humic acid-induced silver nanoparticle formation under environmentally relevant conditions. Environmental Science & Technology, Published online Apr. 1, 2011. dx.doi.org/10.1021/es103946g.

** The effect is called "surface plasmon resonance" and is caused by surface electrons across the nanoparticle oscillating in concert.

####

For more information, please click here

Contacts:
Michael Baum

301-975-2763

Copyright © National Institute of Standards and Technology (NIST)

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 News Press

News and information

Maximum Precision in 3D Printing: New complete solution makes additive manufacturing standard for microfabrication February 26th, 2015

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Bruker-Sponsored Sixth AFM BioMed Conference Highlights Increasing Impact of AFM in Biological Applications February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Laboratories

Dendrite eraser: New electrolyte rids batteries of short-circuiting fibers: Solution enables a battery with both high efficiency & current density February 24th, 2015

Researchers synthesize material for efficient plasmonic devices in mid-infrared range February 16th, 2015

New design tool for metamaterials: Berkeley Lab study shows how to predict metamaterial nonlinear optical properties February 10th, 2015

X-ray pulses uncover free nanoparticles for the first time in 3-D 'Super microscope' reveals unexpected variety of shapes February 4th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Warming up the world of superconductors: Clusters of aluminum metal atoms become superconductive at surprisingly high temperatures February 25th, 2015

SUNY Poly CNSE Researchers and Corporate Partners to Present Forty Papers at Globally Recognized Lithography Conference: SUNY Poly CNSE Research Group Awarded Both ‘Best Research Paper’ and ‘Best Research Poster’ at SPIE Advanced Lithography 2015 forum February 25th, 2015

European roadmap for graphene science and technology published February 25th, 2015

Cutting-edge technology optimizes cancer therapy with nanomedicine drug combinations: UCLA bioengineers develop platform that offers personalized approach to treatment February 24th, 2015

Discoveries

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Simple, Cost-Efficient Method Used to Determine Toxicants Growing in Pistachio February 26th, 2015

In quest for better lithium-air batteries, chemists boost carbon's stability: Nanoparticle coatings improve stability, cyclability of '3DOm' carbon February 25th, 2015

Announcements

Maximum Precision in 3D Printing: New complete solution makes additive manufacturing standard for microfabrication February 26th, 2015

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Bruker-Sponsored Sixth AFM BioMed Conference Highlights Increasing Impact of AFM in Biological Applications February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Environment

Simple, Cost-Efficient Method Used to Determine Toxicants Growing in Pistachio February 26th, 2015

Purification of Industrial Wastewater Using Visible-Light Sensitive Photocatalysts February 24th, 2015

Nanocomposite Membranes Used in Iran for Water Desalination, Sweetening February 16th, 2015

Scientists in Iran Use Nanotechnology for Industrial Purification of Drinking Water February 13th, 2015

Safety-Nanoparticles/Risk management

Potential toxicity of cellulose nanocrystals examined in Industrial Biotechnology journal February 19th, 2015

A breakthrough in nanotoxicology by INRS researchers: Silver nanoparticles and inflammation February 18th, 2015

“Nanorama Laboratory“: Free Tool on Safe Handling of Nanomaterials Now Available in English! February 4th, 2015

Worms lead way to test nanoparticle toxicity: Rice University study validates low-cost, high-throughput technology February 2nd, 2015

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 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE