Lecture 12 Flashcards
What are some examples of how nanoparticles have been dispersed in nature?
Note that the point made at the end is much more important than the examples.
The described below should be coupled with their respective slides found in digital notes to get the full picture!
- “Red-tide” aerosols: This branch of algae, once it reaches optimal conditions, will bloom to reach a reproduction rate. These algae have red pigments that show a red tide in sunlight. The algae also by some type of mechanism fluoresce at night. The important thing about this is that this type of algae releases a toxin that isn’t itself a nanomolecule, but it does have nanostructures. Lucikly these toxins are not that toxic to humans
- “Blue haze” aerosols: Trees at a certain temp will release a large amount of nanomaterial that will reflect the light forming what is known as the blue hazeLuckilyly again this does not affect humans much
- Black ashes” from volcanoes: Ofc the black ashes from volcanoes will release particles some of which can be as small to be in the nanoscale. Those particles in the nanoscale can pose very serious health hazards to the people found within the smoke.
- “Dirty Fog” – “Smog”-from industrialized cities: We suspect that there are nanoparticles released as well but as of yet they haven’t been detected or seen.
The main message of this is that humans have been living and interacting with nanoparticles for a very long time and this could have some serious repercussions.
What are the 3 biggest concerns concerns of nanomaterials? (SO IMP. WILL COME IN THE EXAM)
1) Settling (deposition) and accumulation of nanoparticles
2) Agglomeration of nanomaterials
3) Interaction with the body and with cells
(also nanoparticles are airborne (bad), they have very reactive surfaces (baddd), and the nanoparticles who have different aspect ratios are so badddddd)
Why is it always never recommended to have nanoparticles interact directly with the body and the cells?
Due to the nanoparticles having a very large surface area (which is thus very reactive), they will cause the formation of free radicals in the body, which will result in the initiation of oxidative and inflammation processes in living organisms.
As depicted in the notes
How are humans exposed to nanoparticles?
Look at the notes
Assess the toxicity of carbon, iron oxide, silica, and CdSe nanoparticles.
CdSe - Cadmium is a toxic heavy
metal and appropriate precautions
should be taken when handling it and
its compounds
- Carbon, Silica, and Iron Oxide are
considered inert to the human
health, but when they get into the nanoscale they might have some long-term effects. Bas generally considered less toxic with silica being the least
How does the size of a nanoparticle affect the rate at which it settles and the rate at which it diffuses?
The smaller the particle is the faster it diffuses, the more it stays airborne and the slower it will settle.
The larger the particle, the slower it diffuses, and the faster it will settle.
Both small and large particles will accumulate once in the body and since the smaller nanoparticles are airborne longer they have a larger chance of going into the body.
Which is more dangerous, smaller or larger particles?
Okay, this is a dense question.
If we are talking in all scales, then any particle in the nanoscale is more dangerous than the particles in the microstate and above.
But if we are talking only in the nanoscale, then smaller particles are safer. That is because they travel faster through the body and therefore are eliminated more easily.
Now there is some confusion here since smaller particles (due to their high mobility) can reach deep tissues in our body and settle there, which will of course cause the initiation of oxidative and inflammation processes which are harder to treat.
So overall smaller nanoparticles are in principle safer because they are more easily eliminated from the body, but once allowed to settle will cause larger problems.
What is carbonaceous?
Carbonaceous refers to substances that contain a significant amount of carbon or are composed primarily of carbon. These materials can range from naturally occurring compounds like coal, graphite, and organic matter, to synthetic forms such as carbon-based nanomaterials.
Now carbonaceous nanoparticles from diesel engines have the potential to make their way into our airways and cause some really bad long-term effects.
In what way can the travel of nanoparticles into our tissues be useful?
We can use it in applications such as inhaled “drug delivery” systems!
OKAY, I WANT TO STRESS THAT the DIRECT contact between nanoparticles and any cell in the body no matter whether healthy or not MUST BE AVIODED.
What are the different ways that nanoparticles might make it into our bodies and how to we prevent it?
- Diffusion through the skin: Very little evidence that this happens. It is prevented by wearing gloves and making no direct contact
- Diffusion through and deposition at the
respiratory system: has proven critical for
interaction with nanoparticles. Prevention:
i) Work in well-ventilated areas
(fume-hoods)
ii) keep materials in solution, that way the released nanoparticles wont become airborne but instead stay with the solution
iii) masks. Keep in mind that there is a limited amount of good quality masks that do the job efficiently, but recently with COVID-19, more and more good masks are beginning to arrive.
What is the “asbestos” case and why is it mentioned?
The “asbestos” case is an unfortunate incident where in the 90s people discovered this mineral and used it a lot due to its good insulating properties.
From the amount of times it was used and how popular it was a lot of people became exposed to it, and many started becoming sick. Later on, scientists started to discover that the asbestos particles were inhaled into the lungs and were allowed to settle. Due to the asbestos aspect ratio, it ended up forming networks and zones, which caused cancer in many people.
This taught the world that any chemical substance should be considered and handled as potentially “dangerous” and “toxic” until proven otherwise! With this mindset and the right protection, nanoparticles will not cause humans any harm
Note that asbestos networks formed are in the nanoscale but rather in the microscale!
What is the importance of the aspect ratios for nanoparticles?
A nanoparticle (or generally any particle) that doesn’t have equal aspect ratios (i.e the length is larger than the radius) is considered highly dangerous due to its ability to form networks and zones as it grows from one side faster.
Note that a sphere shape is okay to use
What are the actions now required to take to ensure nanosafety?
- National and International programs for Safety of nanomaterials
- Procedures and prototype safety activities - where scientists have to sign many safety forms to allow them to use some nanomaterials
- New and more efficient methods of detection
- Some documentation and websites available for further reading
- Legislation on nanomaterial use
Note imp
from now onward anything mentioned is considered to be an action towards bringing nanosafety
What is the big challenge
It is a global challenge working towards developing safe technologies.
What are the possible ways to protect against nanomaterials?
In order to protect ourselves we need to be able to develop and collect nanoparticles:
- Air sampling: smoke detectors to (nano)particulate detectors.
- Liquid sampling: methods based on photon correlation spectroscopy, Brownian motion, or zeta potential (charges) measurement
*New particle collection methods: for both air and liquid, e.g. by charge separation
- Filters & Masks: with nano-pore size and nanoparticle selectivity - After COVID the masks and filters development has picked up.
what is the particle sizer (Malvern Instruments Zetasizer Nano ZS)?
It is an instrument used to determine to detect particles and surface charges.
It works by measuring the light scattering that happens in a solution. Different particle sizes will bring about different light scattering
it has a large size range (0.6 nm upwards) and it measures zeta potential (surface charges) for particles from 3 nm to 10 μm.
It is worth noting that from this method you can also determine the charge (like if it is + or -)
What are other particle-size instrumentations and detections?
Found in digital notes
What are the methods for evaluating toxicity?
- Animal tests are controversial and may not give good indications for humans - a case that can be made against this is that animals are different creatures than humans, and they might not give an accurate representation. In the digital notes, you can see examples of this!
- Need for developing in vitro tests on different cell types; in vivo is not always possible. One way to allow for vivo is to protect the toxic nanoparticle by encasing it in a shell of silica (or a non-toxic material)
- Nanoparticles are difficult to analyse because they agglomerate so readily causing confusion about whether to detect a single particle or an unknown amount of particles.
- Dispersion of nanoparticles raises other concerns: Does the dispersant (solvent) change their toxicity? Are the dispersants safe?
What are the important points of evaluation for impact over a lifetime?
before we start note that Impact over a lifetime basically means asseing the impact that nano molecules could have in the future (next 20-30 years)
- Evaluate risks in production and manufacturing of nanomaterials
- Evaluate risks during use and manipulation of the products
- Evaluate end-of-life aspects (how can we get rid of them): recycling? Incineration? Carbon foot-print? (note that nanomaterials form carbon dioxide in their production)
What are the predictive models of nanosafety?
- Can we use the data collected on engineered nanoparticles to predict their impact?
- Can we predict the transport and fate of the nanoparticles released into the environment? - How will the be released at the point of recycling (for example)
- Can we predict the effect that nanoparticles introduce into the body (including the use of drug-release agents)? - In most cases, the good brought by the drug-release agents is better than the harm
- Does the environment modify the nanoparticles? Simulate and predict? - For example, does it change the nanoparticle’s surface charge
Quick note because I don’t want to make a flash card about it: You can make money by teaching nanomaterial safety! This is a business opportunity within the field
What are the challenges for nanomaterials?
Look at the slides. NOTE THAT THIS IS VERY IMPORTANT YOU NEED TO KNOW BY HEART 4 EXAMPLES.
They might ask you questions such as:
a) Identify two application areas where nanomaterials could have a strong impact
in the future.
b) Which type of nanomaterials, amongst the ones discussed in the lectures,
could be used in the technological applications areas you mentioned in a)?
Explain how?
c) Which could be the risks (if any) for health, of the nanomaterials that you
mention in aline a). Note: if no risk, also explain why are they considered safe?
