Conclusion, Introduction, Drug Delivery, Solubility, Nanofibers, Toxicity

Medicine has thrived through the incorporation of nanotechnology in its discipline as the efficacy
of drugs improved significantly due to its implementation in drug delivery, isolation of cancer
cells in the body and reparations in clogged arteries. However, use of nanotechnology can be risky,
as particles behave differently at a nanoscale level. This unpredictability can pose hazards to
human health if it is unable to be controlled in its application in medicine. Substances such as
engineered fibrous nano-materials can cause inflammation on lungs while the small size of
individual particles allows them to enter cells and form clumps. This report will explore the risks
and hazards which nanotechnology carries in its application in medicine on human health.

Nanoparticles hold great significance in the field of medicine due to their frequent emergence:
they are everywhere from wound dressings to drug delivery. However, much of the disadvantages in
its application is yet to be researched, as whatever little information is available, it only comes
from inhaled nanoparticles. If not researched thoroughly, the risk of nanoparticles could increase
significantly, as it has already been demonstrated in lab rats which resulted in lung inflammation
and blood clotting. Furthermore, the high surface area of nanoparticles makes them particularly
sensitive when it comes to reactivity, which inside the human body could trigger unwanted
reactions, in turn causing damage to cells and organs. Therefore, the subject of nanoparticles
should be treated with caution, especially when it comes to application on humans in order to allow
for safer usage in medicine.

Nanofibre membranes from bipolymers are used as drug carriers or bioactive compounds. The benefit
of this is that the membranes are engineered to specifically target diseased cells, therefore
reducing the damage done to healthy cells. The benefits of using nanoparticles in drug delivery is
that it is possible to attach ethylene glycol molecules, which enables the nanoparticles to
circulate in the blood stream. It is ethylene glycol molecules which stop the white blood cells
from attacking the nanoparticles. While the benefits of nanoparticles in drug delivery are immense,
there are serious adverse effects which need to be researched further: cationic nanoparticles,
which are ligand coated nanoparticles used as agents for drug delivery, such as gold and
polystyrene have been shown to cause haemolysis (rupture of red blood cells) and blood clotting (De
Jong and Borm, 2008). Positive correlation is also observed between nanoparticle exposure and the
amount of cardiovascular diseases; however, there is no definitive explanation. Toxicological
studies have demonstrated that certain nanoparticles can gain access to the blood following
inhalation and can enhance experimental thrombosis (blood clotting in circulatory system) but it is
not clear whether this was an effect of pulmonary inflammation or particles translocated to the
blood. Another type of nanoparticle, DEP (Diesel exhaust particulate), was shown to cause altered
heart rate in hypertensive rats, whereas high concentrations of anionic nanoparticles and cationic
nanoparticles were toxic for the BBB (blood and brain barrier) (De Jong and Borm, 2008).

Different types of nanoparticles have varying solubility, and it is those nanoparticles with low
solubility that could pose the most health risks. The risks are greater if the nanoparticles
comprise inorganic metal oxides and metal, as they could react with bio-molecular structures within
the body. Another factor to consider is if they are able to be broken down and be degraded: it
would lead to the nanoparticles to accumulate within the body and damage organs. Furthermore, due
to its high reactivity and electrical charge, nanoparticles create conditions within the body where
they come together to form larger particles, described as "particle aggregation". This could
potentiate the risks even further as this alters their physiochemical properties leading to unknown
reactions inside cells.

Nanofibers are fibres that have diameters of less than 1000 nm, and their medical applications
range from wound dressings to artificial organ transplants. Nanofibers are created by an
electrospinning process that ranges from 10 nm to several hundred nanometres. The unique process
through which it is made gives the nanofibers special properties due to its high surface area to
mass ratio, such as low density, high pore volume, and tight pore size. Researchers have also
demonstrated new ways to make nanofibers out of proteins naturally occurring in blood, which makes
it ideal for use in bandages as they eventually dissolve in the body (Hegde, Dahiya, and Kamath,
2005). This also makes it possible to add antibacterial material and drugs to the nanofiber
structure, minimising infection rate, blood loss, and making it more effective as it is absorbed by
the body. Another field within medicine where nanofibers are used is tissue engineering, making
them possible substrates for growing cells. Nanofiber substrates effectively support cell
multiplication and enable tissue replacement prepared from a patient's cells. The material it is
made from also makes it possible to incorporate different bioactive materials and drugs. Barrier
textiles, when containing hydrophobic nanofibre layers, work as effective barriers for
microorganism penetration, such as viruses and bacteria (Nanofiber applications, 2004). However,
nanofibres can also pose significant health risks to humans. When silver nanofibres of different
lengths were injected into lungs of mice, those larger than 5000 nm in size became lodged in lungs
and caused inflammation while the smaller ones cleared away (BBC, 2012). Still, it is questionable
whether the same results are applicable to humans, as the test was done on mice.

The toxicity of the nanoparticles is also dependent on its size, as particles at the nanoscale
level lead to an increase in surface area to mass ratio. This means more chemical molecules are
present on the surface of the nanoparticles, which enhances toxicity. During the study of low
toxicity particles, TiO[2 ]particles with higher surface area were shown to induce more severe lung
inflammation and particle lymph node burden compared to BaSO[4 ]particles with lower surface area
(Tran et al 2000). Furthermore, their large surface area makes them highly reactive, which could
lead to activate unknown chemical reactions or to bond with toxins, allowing for nanoparticles to
enter cells other than the ones targeted.

Shapes also play a key role in the characteristics such as the respirability and inflammatory
potential of individual nanoparticles. A prime example of these are nanotubes. In addition to being
carcinogenic, single - wall carbon nanotubes where shown to induce Lung Granulomas, a type of
inflammation, and thus demonstrated to be very toxic. However, this could also be due to the high
mass dose. To add, studies using human keratinocyte cell line also showed that carbon nanotube
exposure resulted in cell toxicity and accelerated oxidative stress (Shvedova et al 2003), which is
an imbalance between the free radical production in the human body and the ability to neutralise
its harmful effects.

Nanotechnology is a branch of technology which involves manipulating with structures and properties
at the nanoscale range, from 1 to 100 nanometres. A particle which is 1 nanometre in size is 1 ×
10^-9 metres small - a billionth of a metre. With the concept introduced initially in 1959 by
physicist Richard P. Feynman during his "There's Plenty of Room at the Bottom" talk, where he
expressed the ability to control and manipulate individual atoms and molecules, the study has today
developed exponentially to revolutionise perspectives in cosmetics industry, agriculture and most
recently, medicine.

One of the major characteristics of nanoparticles is its toxicity and so far most of the research
done around this area comes from inhaled nanoparticles in the air. What makes nanoparticles toxic
in particular is their individual chemical properties, with Carbon Black nanoparticles causing more
severe health effects compared to its other counterparts. However, it is subjective to
contamination caused by human activity, such as pollution, as well as the fact that nanoparticles
in the ambient air have complex composition, with organic and metal components such as metallic
iron interacting, which may cause the adverse health effects. Metallic iron was shown to potentiate
the effect of Carbon Black nanoparticles through increased reactivity (Wilson et al 2002).


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