Brain Health: Are Nanoparticles Saints or Sinners?

Posted by: michael  :  Category: Factors affecting Brain Health

Nanoparticles hold enormous potential to change many aspects of our existence… some for the better, some for the worse. So what are nanoparticles; where do they come from; what have they got to do with brain health; and why have I referred to them as saints or sinners?

Let’s start our journey…
When we meet someone unexpectedly we often say “it’s a small world”. Well, you ain’t seen nothin’ yet!  Welcome to nano-land… where things are not just very small or even extremely small but unbelievably small!

In nano-land particles are so small that when you play (move, control, build) with them you do so with molecules and atoms as if they were the plastic bricks you used to build things when you were a child. So in nano-land we might build something with a cluster of atoms rather than a pile of plastics bricks

In case you are wondering, an atom is a basic unit… the basic building block of matter. Atoms where once considered indivisible, but we now know that the energy released in the process we call nuclear fission is achieved by splitting an atom. Just so we are all clear, when we work with nanoparticles the atoms we use have not been split   Molecules are bigger than atoms of the same material because they are composed of two or more atoms

Okay, enough of that stuff… here’s a question: Why would you want to play around with atoms when you can have a chunk of the material.

Well, this where it gets really interesting, so let me try and illustrate why by using silver as an example.

Silver is used in making jewellery, in part, because it tarnishes only slowly – that is to say it is not very reactive with the air or other materials. But if you take a piece of silver and keep on dividing it up until it’s so small that it’s much smaller than, for example, a red blood cell (and that’s pretty small) – something quite extraordinary happens.

What do you think it is?

It changes from being the reliable, ever so predictable – some might say, stodgy – metal to a reactive and somewhat unpredictable package of potential. Okay, so I’ve exaggerated a bit, but it certainly has exciting characteristics that the original chunk doesn’t display… for example, antibacterial properties.

Wow! What on earth is going on?

Introducing nanoparticles:. The  antibacterial properties referred to are related to the total surface area of the silver nanoparticles. Now we’re in nano-land we’d better get used to nano-things, because we’ll find nanotechnology, nanoscience, nanotoxicity, nanoethics, nanomedicine, as well as a whole lot more nano things.

So what is a nanoparticle?
Essentially, two criteria are used for identifying a nanoparticle. However, it is difficult to give a precise definition because my understanding is that while most do, not all nanoparticles meet both criterion.

Anyway, I don’t want to unnecessarily complicate things so the following descriptions will do for our purpose…
Very, very small particles (bits) of material that display different properties from the bulk material are called nanoparticles. Although there is no universally agreed definition of a nanoparticle it is accepted that the size of the particle should be another criterion. The agreed size range is from 0.1nm to 100nm.

What is an nm? It is an abbreviation of nanometre. One nm is one billionth of a metre (a metre being about 39 inches). That means if I take one metre and divide it by 1,000.000.000 I will have 1nm remaining. And that’s seriously small, like 0.000000039 inches!

Earlier I said nanoparticles display different properties from the bulk material from which they came. But why is that so?

Two popular explanations are put forward. The first is that volume for volume nanoparticles exhibit a larger surface area than the bulk piece and that fact has the potential to make them more reactive. It’s not hard to see why nanoparticles would have a larger surface area. If, for example, after breaking a bar of chocolate in half, you examine where it broke there are two new ends exposed that were previously joined. So that gives the two pieces a combined surface area greater than the original whole piece as you’ll no doubt discover when you come to wrap it up.

Imagine how much the surface area would increase if you were to break the chocolate pieces time and time again. Having a larger surface area makes nanoparticles potentially much more reactive.

The important thing to remember is that nanoparticles display different properties, characteristics, qualities or whatever you want to call them from the bulk material from which they came.

But why all the excitement about nanoparticles… after all they are not a new discovery. In fact, nanoparticles have been around for tens of thousands of years, for example, they occur naturally in volcanic dust, soil dust and sea salt spray. They also occur from burning fossil fuels and show up, for example, in vehicle exhaust emissions. The exciting news is that scientists have discovered how to make them which gives them access to a wide range of new and novel nanomaterials.

It is that fact that has enabled scientists to make new technologies and materials with potential applications in such diverse areas as communications, computers, robots medicine, stain proof materials, sunscreens, scratchproof paints and a myriad of other novel applications. 

By now you must be wondering what nanoparticles have got to do with brain health. As you’ll discover in a moment or two, the answer is plenty!

And that’s where the “saint or sinner” arises.
You see, nanoparticles have potential for far-reaching applications in the diagnosis and treatment of brain disease, and not just in brain cancer where most of the current research is focussed. But it’s not all good news. Why not?

Well, some nanoparticles can potentially cause brain damage because of their ability to pass through the blood brain barrier (BBB) into the brain itself.

The BBB is a tight seal of endothelial cells (cells that line the interior surface of the body’s blood vessels) in the brain. Basically, the purpose of the BBB is to protect the brain from toxins and other potentially harmful substances circulating in the bloodstream. The BBB selectively allows certain substances to pass through into the brain and one determinant of what gets through seems to be particle size. That fact exposes a possible means to get through the BBB using nanoparticles.

Welcome to nanomedicine….
1) The case for the Saints
(potential benefits) – bear in mind that much of the research is performed on rodents and does not necessarily translate to humans.

            1.1 Brain cancer imaging and surgery
It is difficult to treat brain cancer. Firstly, because imaging results are often imprecise it is hard to properly assess the spread of the tumour. Second, conventional treatment is by gaining access through the skull and removing as much of the tumour as can be done safely. As you might expect it is difficult for the surgeon to be sure that all the cancerous tissue has been removed so surgery is followed by radiation or chemotherapy in an effort to kill any cancer cells left in surrounding tissue.

 However, If doctors inject fluorescent nanoparticles into the bloodstream, and can get them to pass through the BBB, the contrast between cancerous cells and normal tissue will be much clearer and allow much greater accuracy in removing the tumour. And that’s a sample of the promise of nanoparticles.

            1.2 Killing brain cancer cells
Researchers at the University of Chicago have developed a technique that binds antibodies (proteins found in the blood and tissues that detect and destroy foreign invaders like bacteria) to nanoparticles and pass through the BBB. Broadly the idea is that the ‘modified’ nanoparticles will attach to cancerous cells and then be activated by light to create a substance that will destroy the cancer cells and leave the healthy surrounding tissue unharmed.

            1.3 Improved drug delivery to brain
In order to benefit from new drugs, the drugs first need to pass through the BBB to get to the brain. Research at the University of Portsmouth (UK) is employing special nanoparticles to create temporary openings in the BBB to allow for improved drug delivery. The particles will also act as a drug delivery container so that the drugs get straight to the brain

            1.4 Keeping brain cells alive
Researchers at the University of Central Florida found  they can prolong the life of brain cells using special nanoparticles. The finding raises hopes that the particles could one day be used to treat age-related disorders such as Alzheimer’s disease.

            1.5 Mopping up free radicals
The same researchers also suggested that certain special nanoparticles are four times as good at mopping up free radicals as natural scavengers such as vitamin C or vitamin E, and also seem to last much longer within the cells.

2. The case for the Sinners (potential hazards)

Size is the key to determining the potential toxicity of a particle. The smaller the particle the greater its surface area (for a given volume) and the more chemically reactive it is likely to be. The more chemically reactive a particle, the more readily it can produce free radicals. Hey, didn’t I just say that researchers found that a certain nanoparticle was very effective in mopping up free radicals – interesting! Anyway, the point I wanted to make is that free radicals have potential cause DNA damage which can lead to premature aging and potential early onset of age-related diseases.

Much of the current research on the possible deleterious effects of nanoparticles on human health is at what I’d call the ‘in principle” stage. By that I mean that we can say that this or that effect is very likely, or has a strong expectation, but we don’t yet have conclusive proof to back up the claims. While there is compelling evidence in some areas by and large we don’t yet know enough to be definitive and, anyway, often the full effects only become evident after many years of ‘exposure’ to a particular hazard.

So it is fair to say that we don’t know how nanoparticles will behave in the body – how, for example, the accumulation of nanoparticles might manifest in the body’s organs including the brain.. Nor do we know how nanoparticles might interfere with the body’s biological processes.

The fact that nanoparticles can get access to the body’s cells, tissues and organs should be of major concern to those of us concerned about our long-term health. Nanoparticles can get into the bloodstream through inhalation, ingestion and possibly through fractured or even stretched skin. Once in the bloodstream certain nanoparticles can get through the BBB straight to the brain. For me, that’s scary too.

But there’s more that concerns me: it’s the question of whether nanoparticles can interfere with the body’s immune system. I guess the answer is yes… but what we don’t know is whether that will be beneficial or deleterious.

In short, there is so much we don’t know about the potential effects of nanoparticles on human health in general, let alone on the brain.

Well, there you have it… a very brief layman’s overview of the exciting world of nanoparticles and their potential health benefits and hazards.

As most of my regular readers know my philosophy is the healing comes from within. By that I mean we already have all the knowledge we need, we are simply having trouble working out how to access and use it.  

So for my part I’ll name nanoparticles as Sinners. But then I’m not suffering from brain cancer.

What do you think? Are nanoparticles Saints or Sinners?

As always, I would be very interested in your comments. If you like this post please let your friends know – after all, maintaining good brain health is important for everyone, no matter how young or how old.

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