Nanoparticle Blog

What are nanoparticles used for? This blog collects and explains applications and further info from the web.

Oct 29

Water treatment by nanoparticles

Treating water with the help of nanoparticles is a huge topic in nanotechnology. Many nano-effects can contribute to a better water quality, by killing bacteria, removing toxic metals, decomposing organic contaminants, or even removing oil.

Such nanoparticle-initiated processes can be used in the field of groundwater remediation as well as in water treatment plants for drinking water, and shall - in the future - even be applied to single drinking portions.

The Guardian wrote an illustrative report about nanotech advances to the cleaning of drinking water for the developing world, especially listing nanoparticles from magnetite, silver and titania:

SciDev.Net has summarized “nano-based products” like nanofiltration membranes, nanosponges, or nanorust that are “relevant to developing countries” for specific kinds of water treatments:

In the field of groundwater remediation, the use of zero-valent iron nanoparticles has already become quite popular. During the process, the particles are usually dissolved.

For example, Nanoiron s.r.o. applied their material at a groundwater remediation site in the Czech Republic. It eliminated chlorinated hydrocarbons and hexavalent chromium showing convincing quantitative results:

Fe(0) nanoparticles by NANOIRON

Lehigh Nanotech from Pennsylvania are listing former projects in which their iron nanoparticles were applied for environmental remediation all over the US:

Field trials have also been conducted in Ontario, Canada. A recent press release from Sydney explains how iron nanoparticles helped to clean Canadian groundwater that was contaminated with toxic chemicals. It could also become relevant to hundreds of Australian sites:

For TCE, a carcinogen from degreasers that contaminates goundwaters all over the world, a recent publication by Rice University has demonstrated that nanoparticles based on palladium clean TCE “a billion times faster” than iron-based reductants:

Even pollution with oil could be removed with the help of nanoparticles, as demonstrated recently by researchers from Genova. They used a polyurethane foam that can swim on water surfaces. Such foams were equipped with microspheres from PTFE (binding oil and repelling water) and nanoparticles from iron oxide (for a subsequent magnetic collection) to potentially bind and remove oil from contaminated water surfaces:

Oil removal from water (Photo by Istituto Italiano Tecnologia)

So while some people are worrying about nanoparticles as water contaminants, others are employing them to get rid of contaminants. Sounding contradictory, this again demonstrates that every type of nanoparticles has different effects - and that “nanoparticles” are never generally magic, malicious, world-saving - or contaminating.

Sep 24

Silver nanoparticles can cause damage to human tissue

Today CENIDE, a nanotech center in Duisburg and Essen, Germany, announced that a series of research results has shown adverse health effects of silver nanoparticles, making them unsuitable for certain medical products.

pure laser-generated silver nanoparticles (100 nm)The press release title “The overrated precious metal" does not refer to the antibacterial effect of silver, which is undoubted. It helps to eliminate bacteria due to the emission of silver ions from the nanoparticle surface.

(Photo: pure, laser-generated silver nanoparticles.)

However, the group of Prof. Barcikowski found that high silver concentrations can also damage human fibroblasts when nano-silver products are exposed specifically to human tissue. This can be relevant for medical products like implants or catheters, as fibroblasts are involved in the healing of wounds. In addition, albumin (which is present in our blood) can weaken the antibacterial effect of nano-silver, making it even less useful for certain medical products.

It is important to understand, though, that these findings do not refer to non-medical products that make use of silver nanoparticles e.g. for hygienic purposes. Prof. Barcikowski explains that "both the dose and the applicational environment are decisive - so for certain applications, nothing speaks against controlled amounts of silver well below the toxicity threshold."

The reason why the current studies seem so reliable is the manufacturing process that the group employed: laser ablation in liquids. This physical process excludes any side effects from chemical impurities and generates nanoparticles from pure silver directly e.g. in a polymeric matrix. The same technology also allows to simply exchange silver by other metals like zinc, iron, or magnesium. These will now be investigated as potential alternatives to silver for certain medical products.

Link to CENIDE Press Release, published by Nanowerk:

Sep 10

Bimetallic nanoparticles as catalysts for biofuels

Core-shell nanoparticle in an apoferritin cage ( a recent article, summarizes why bimetallic core-shell nanoparticles, e.g. consisting of a gold core with a silver shell, can serve as catalysts in processes like the conversion of biomass into fuel.

In the scientific article, a protein cage template from apoferritin (Apo) was used as a “nanoreactor” for the synthesis of such nanoparticles.

Article by

Original article (Journal of Materials Chemistry):

Sep 6


Archimedes' principleResearchers from Italy have explained that Archimedes’ principle cannot be applied to nanoparticle dispersions. Despite the large density of metallic nanoparticles, some of them can float on the top of the lighter fluid due to perturbation effects in the colloid.

Article in RSC Chemistry World Blog:

Original article in RSC Soft Matter:

Aug 22

Aug 12

Silver kills germs by ion emission

What many publications about the effects of silver nanoparticles had implied for years has now been focused on explicitly in a Nano Letters publication from July 2012: the well-known antibacterial effect of nano-silver solely goes back to the emission of ions.

Silver nanoparticles in a surrounding that does not allow any release of ions do not show antibacterial behavior. Reversely, an oxidizing surrounding (such as air or water) supports antibacterial activity of nano-silver products.

Nano Letters: Antibacterial Activity of Silver Nanoparticles

Link to Nano Letters publication: 

Link to a summary on

Aug 6

Aug 1

Jul 28

CNN on “Dangers of Colloidal Silver”

A TV report from 2007 shows a man who has been taking nano-silver dispersions orally for years and whose skin color has turned blue-gray - which is scientifically known as “argyria”. This illustrates that many people seem to believe in nano-silver as an antibacterial health elixier, although the result does not look very convincing.

In November 2011, the Nanoparticle Blog published an article about “colloidal silver for oral taking”, explaining that dubious websites promoting colloidal silver should not be taken serious. Instead, the well-known antibacterial effect of nano-silver should rather be used for local treatments of surfaces that are known to be in contact with unwanted bacteria.

Blog article on “colloidal silver for oral taking”:

Wikipedia article on “argyria”:

Link to the CNN report on YouTube:

Jul 18

Nano-silicon for energy conversion

Germany’s “international broadcaster”, Deutsche Welle, has published a report about a new application of silicon nanoparticles. 

German scientists at the “Center for Nanointegration” at University of Duisburg-Essen are explaining how, instead of solar energy, heat energy shall now be converted into electricity using semiconductors at the nano-scale.

With this approach, they want nanoparticles from doped silicon to contribute to an efficient conversion of waste heat into electricity.

doped silicon (DW)

Direct link to the article by Deutsche Welle:„16091377,00.html

Jul 12
Manifold applications of Nanoparticles:This impressive overview of nanoparticle applications (that were known by 2009) was published on the webpages of the Deakon Institute for Frontier Materials.
Direct link to the webpage:

Manifold applications of Nanoparticles:
This impressive overview of nanoparticle applications (that were known by 2009) was published on the webpages of the Deakon Institute for Frontier Materials.

Direct link to the webpage:

Jul 7

Graphene production: patent overview

Graphene (Wikimedia) - by AlexanderAlUSAs the latest nanomaterial star, graphene has superseded carbon nanotubes as to public interest and potential applications. The 2-D carbon is mostly available in the form of nanoparticle flakes.

Nanowerk has published an abridged version of a review article by K. S. Sivudu and Y. Mahajan on the worldwide patent situation on graphene production methods.

Link to the Nanowerk spotlight article:

Jul 3

Jun 24

Extraterrestrial nanoparticles

Two recent discoveries have dealt with the presence of nanoparticles outside of the earth’s atmosphere.

One of them is about lunar dust and has even made it into TIME Magazine: Nanoparticles have now been detected in silica spheres contained in the moon dust that was brought to earth by the Apollo missions more than 40 years ago. Apart from their embedment in silica, these particles may be a normal ingredient of moon dust that, for example, leads to its strong electrostatical behavior that the astronauts observed.

lunar soil morphology show that fine, submicron dust particles
Figure by ISRN: SEM micrographs of studied lunar soil

The other article explains that in Mexico, nanodiamonds and other nanoparticles were found in a 12,900-year-old layer of dark sediment. Such particles had so-far only been found in 65-million-year-old layers from the time at which a major extraterrestrial impact had led to the extinction of the dinosaurs. 12,900 years ago, a similar impact of a comet or asteroid is supposed to have caused the extinction of mammoths and other large animals.

We do know that - apart from artificial nanomaterial - some nanoparticles have always been arising from natural processes on earth. Now, we have proof that some kinds of nanoparticles have even been imported from space.

TIME article on moon dust:
National Geographic article:
ISRN Astronomy and Astrophysics:

Nano Magazine (nanodiamonds):
UC Santa Barbara release on extraterrestrial sediments:

Jun 21

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