Aug 252013
 

Gold255

Gold nanoparticles with special coatings can deliver drugs or biosensors to a cell’s interior without damaging it

Cells are very good at protecting their precious contents — and as a result, it’s very difficult to penetrate their membrane walls to deliver drugs, nutrients or biosensors without damaging or destroying the cell. One effective way of doing so, discovered in 2008, is to use nanoparticles of pure gold, coated with a thin layer of a special polymer. But nobody knew exactly why this combination worked so well, or how it made it through the cell wall.

Now, researchers at MIT and the Ecole Polytechnique de Lausanne in Switzerland have figured out how the process works, and the limits on the sizes of particles that can be used. Their analysis appears in the journal Nano Letters, in a paper by graduate students Reid Van Lehn, Prabhani Atukorale, Yu-Sang Yang and Randy Carney and professors Alfredo Alexander-Katz, Darrell Irvine and Francesco Stellacci.

Until now, says Van Lehn, the paper’s lead author, “the mechanism was unknown. … In this work, we wanted to simplify the process and understand the forces” that allow gold nanoparticles to penetrate cell walls without permanently damaging the membranes or rupturing the cells. The researchers did so through a combination of lab experiments and computer simulations.

The team demonstrated that the crucial first step in the process is for coated gold nanoparticles to fuse with the lipids — a category of natural fats, waxes and vitamins — that form the cell wall. The scientists also demonstrated an upper limit on the size of such particles that can penetrate the cell wall — a limit that depends on the composition of the particle’s coating.

The coating applied to the gold particles consists of a mix of hydrophobic and hydrophilic components that form a monolayer — a layer just one molecule thick — on the particle’s surface. Any of several different compounds can be used, the researchers explain.

“Cells tend to engulf things on the surface,” says Alexander-Katz, an associate professor of materials science and engineering at MIT, but it’s “very unusual” for materials to cross that membrane into the cell’s interior without causing major damage. Irvine and Stellacci demonstrated in 2008 that monolayer-coated gold nanoparticles could do so; they have since been working to better understand why and how that works.

Since the nanoparticles themselves are completely coated, the fact that they are made of gold doesn’t have any direct effect, except that gold nanoparticles are an easily prepared model system, the researchers say. However, there is some evidence that the gold particles have therapeutic properties, which could be a side benefit.

Gold particles are also very good at capturing X-rays — so if they could be made to penetrate cancer cells, and were then heated by a beam of X-rays, they could destroy those cells from within. “So the fact that it’s gold may be useful,” says Irvine, a professor of materials science and engineering and biological engineering and member of the Koch Institute for Integrative Cancer Research.

Significantly, the mechanism that allows the nanoparticles to pass through the membrane seems also to seal the opening as soon as the particle has passed. “They would go through without allowing even small molecules to leak through behind them,” Van Lehn says.

Irvine says that his lab is also interested in harnessing this cell-penetrating mechanism as a way of delivering drugs to the cell’s interior, by binding them to the surface coating material. One important step in making that a useful process, he says, is finding ways to allow the nanoparticle coatings to be selective about what types of cells they attach to. “If it’s all cells, that’s not very useful,” he says, but if the coatings can be targeted to a particular cell type that is the target of a drug, that could be a significant benefit.

Read more . . .

 

The Latest on: Gold nanoparticles
  • Method Uses DNA, Nanoparticles and Lithography to Make Optically Active Structures
    on January 21, 2018 at 1:46 am

    Using DNA as a key tool, the scientists took gold nanoparticles of different sizes and shapes and arranged them in two and three dimensions to form optically active superlattices. The structures could be programmed to exhibit almost any color across the ... […]

  • New Class of Light-Bending Material Spun With DNA and Gold Nanoparticles Can Achieve First Real-Life Invisibility Cloak
    on January 19, 2018 at 4:33 am

    In a huge achievement spanning both chemistry and physics, scientists have found a way to create entirely new classes of material that can bend oncoming light around them, making them appear invisible. No, that is not hyperbole, and yes, this is how the ... […]

  • New method uses DNA, gold nanoparticles and top-down lithography to fabricate optically active structures
    on January 18, 2018 at 12:22 pm

    Researchers have developed a new method to precisely arrange nanoparticles of different sizes and shapes in two and three dimensions, resulting in optically active superlattices. EVANSTON - Northwestern University researchers have developed a first-of-its ... […]

  • Metal nanoparticles for imaging guided phototherapy
    on January 18, 2018 at 2:08 am

    (Nanowerk News) National University of Singapore (NUS) chemists have recently discovered that gold-silver (Au-Ag) nanoparticles can be used to image and provide concurrent treatment for bacterial infections. The global spread of multidrug-resistant ... […]

  • How gold nanoparticles may make killing tumors easier
    on January 17, 2018 at 9:26 am

    One of the ways to kill a cancer is to cook it, since heat can kill cells. The trick, of course, is to only cook the cancer and not the surrounding tissue. To do this, you need to have an accurate idea of the extent of a tumor, a precise mechanism for ... […]

  • Shape and Size Measurements of Gold Nanoparticle
    on January 12, 2018 at 4:17 am

    Gold nanoparticles hold many applications in various areas, such as coatings, cosmetics and drug delivery – usually in extremely low concentrations. The ultimate product performance is based on the nanoparticles’ chemical nature, as well as their shape ... […]

  • Gold photothermal therapy: A positive for negative margins
    on January 10, 2018 at 12:47 pm

    The group used recently developed gold bipyramidal nanoparticles coated with polyethylene glycol. The bipyramidal nanostructure showed some preferable photothermal properties, negligible off-target toxicity was observed, and tumoral accumulation in an ... […]

  • Israeli researchers harness gold in battle with cancer
    on January 9, 2018 at 1:57 am

    The key was to get the gold to settle onto the tumors.” So, the researchers attempted to bind tiny particles of gold – nanoparticles that can be bought commercially — to a drug that is commonly used to treat the tumors, cetuximab. Through a chemical ... […]

  • Global Gold Nanoparticles Testing Services Industry 2017 Market Report
    on January 9, 2018 at 12:33 am

    The report firstly introduced the Gold Nanoparticles Testing Services basics: definitions, classifications, applications and market overview; product specifications; manufacturing processes; cost structures, raw materials and so on. Then it analyzed the ... […]

via Google News and Bing News

Other Interesting Posts

Leave a Reply

%d bloggers like this: