Tag Archives: Ag nanoparticles

“Living” bandages made from biocompatible anti-burn nanofibers

A February 16, 2018 news item on Nanowerk announces research from a Russian team about their work on “living” bandages,

In regenerative medicine, and particularly in burn therapy, the effective regeneration of damaged skin tissue and the prevention of scarring are usually the main goals. Scars form when skin is badly damaged, whether through a cut, burn, or a skin problem such as acne or fungal infection.

Scar tissue mainly consists of irreversible collagen and significantly differs from the tissue it replaces, having reduced functional properties. For example, scars on skin are more sensitive to ultraviolet radiation, are not elastic, and the sweat glands and hair follicles are not restored in the area.

The solution of this medical problem was proposed by the researchers from the NUST MISIS [National University of Science and Technology {formerly Moscow Institute of Steel and Alloys State Technological University})] Inorganic Nanomaterials Laboratory, led by PhD Anton Manakhov, a senior researcher. The team of nanotechnology scientists has managed to create multi-layer ‘bandages’ made of biodegradable fibers and multifunctional bioactive nanofilms, which [the bandages] prevent scarring and accelerate tissue regeneration.

A February 14, 2018 NUST MISIS press release, which originated the news item, provides more detail,

The addition of the antibacterial effect by the introduction of silver nanoparticles or joining antibiotics, as well as the increase of biological activity to the surface of hydrophilic groups (-COOH) and the blood plasma proteins have provided unique healing properties to the material.

A significant acceleration of the healing process, the successful regeneration of normal skin covering tissue, and the prevention of scarring on the site of burnt or damaged skin have been observed when applying these bandages made of the developed material to an injured area. The antibacterial components of multifunctional nanofibers decrease inflammation, and the blood plasma with an increased platelet level — vital and multi-purposed for every element in the healing process — stimulates the regeneration of tissues. The bandages should not be removed or changed during treatment as it may cause additional pain to the patient. After a certain period of time, the biodegradable fiber simply “dissolves” without any side effects.

“With the help of chemical bonds, we were able to create a stable layer containing blood plasma components (growth factors, fibrinogens, and other important proteins that promote cell growth) on a polycaprolactone base. The base fibers were synthesized by electroforming. Then, with the help of plasma treatment, to increase the material`s hydrophilic properties, a polymer layer containing carboxyl groups was applied to the surface. The resulting layer was enriched with antibacterial and protein components”, noted Elizabeth Permyakova, one of the project members and laboratory scientists.

The researchers have made images of their work available including this one,

Courtesy NUST MISS [downloaded from http://en.misis.ru/university/news/science/2018-02/5219/]

There is doesn’t appear to be an accompanying published paper.

Smaller (20nm vs 110nm) silver nanoparticles are more likely to absorbed by fish

An Oct. 8, 2015 news item on Nanowerk offers some context for why researchers at the University of California at Los Angeles (UCLA) are studying silver nanoparticles and their entry into the water system,

More than 2,000 consumer products today contain nanoparticles — particles so small that they are measured in billionths of a meter.

Manufacturers use nanoparticles to help sunscreen work better against the sun’s rays and to make athletic apparel better at wicking moisture away from the body, among many other purposes.

Of those products, 462 — ranging from toothpaste to yoga mats — contain nanoparticles made from silver, which are used for their ability to kill bacteria. But that benefit might be coming at a cost to the environment. In many cases, simply using the products as intended causes silver nanoparticles to wind up in rivers and other bodies of water, where they can be ingested by fish and interact with other marine life.

For scientists, a key question has been to what extent organisms retain those particles and what effects they might have.

I’d like to know where they got those numbers “… 2,000 consumer products …” and “… 462 — ranging from toothpaste to yoga mats — contain nanoparticles made from silver… .”

Getting back to the research, an Oct. 7, 2015 UCLA news release, which originated the news item, describes the work in more detail,

A new study by the University of California Center for Environmental Implications of Nanotechnology has found that smaller silver nanoparticles were more likely to enter fish’s bodies, and that they persisted longer than larger silver nanoparticles or fluid silver nitrate. The study, published online in the journal ACS Nano, was led by UCLA postdoctoral scholars Olivia Osborne and Sijie Lin, and Andre Nel, director of UCLA’s Center for Environmental Implications of Nanotechnology and associate director of the California NanoSystems Institute at UCLA.

Nel said that although it is not yet known whether silver nanoparticles are harmful, the research team wanted to first identify whether they were even being absorbed by fish. CEIN, which is funded by the National Science Foundation, is focused on studying the effects of nanotechnology on the environment.

In the study, researchers placed zebrafish in water that contained fluid silver nitrate and two sizes of silver nanoparticles — some measuring 20 nanometers in diameter and others 110 nanometers. Although the difference in size between these two particles is so minute that it can only be seen using high-powered transmission electron microscopes, the researchers found that the two sizes of particles affected the fish very differently.

The researchers used zebrafish in the study because they have some genetic similarities to humans, their embryos and larvae are transparent (which makes them easier to observe). In addition, they tend to absorb chemicals and other substances from water.

Osborne said the team focused its research on the fish’s gills and intestines because they are the organs most susceptible to silver exposure.

“The gills showed a significantly higher silver content for the 20-nanometer than the 110-nanometer particles, while the values were more similar in the intestines,” she said, adding that both sizes of the silver particles were retained in the intestines even after the fish spent seven days in clean water. “The most interesting revelation was that the difference in size of only 90 nanometers made such a striking difference in the particles’ demeanor in the gills and intestines.”

The experiment was one of the most comprehensive in vivo studies to date on silver nanoparticles, as well as the first to compare silver nanoparticle toxicity by extent of organ penetration and duration with different-sized particles, and the first to demonstrate a mechanism for the differences.

Osborne said the results seem to indicate that smaller particles penetrated deeper into the fishes’ organs and stayed there longer because they dissolve faster than the larger particles and are more readily absorbed by the fish.

Lin said the results indicate that companies using silver nanoparticles have to strike a balance that recognizes their benefits and their potential as a pollutant. Using slightly larger nanoparticles might help make them somewhat safer, for example, but it also might make the products in which they’re used less effective.

He added that data from the study could be translated to understand how other nanoparticles could be used in more environmentally sustainable ways.

Nel said the team’s next step is to determine whether silver particles are potentially harmful. “Our research will continue in earnest to determine what the long-term effects of this exposure can be,” he said.

Here’s an image illustrating the findings,

Courtesy ACS Nano

Courtesy ACS Nano

Here’s a link to and a citation for the paper,

Organ-Specific and Size-Dependent Ag Nanoparticle Toxicity in Gills and Intestines of Adult Zebrafish by Olivia J. Osborne, Sijie Lin, Chong Hyun Chang, Zhaoxia Ji, Xuechen Yu, Xiang Wang, Shuo Lin, Tian Xia, and André E. Nel. ACS Nano, Article ASAP DOI: 10.1021/acsnano.5b04583 Publication Date (Web): September 1, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.