Imagine being able to completely customize and move around your DNA to change anything you desire or not having to worry about cancer because technologies existed to eradicate it at the source. Sounds like something out of a science-fiction movie? It can soon become reality with the help of nanotechnology. However, before we begin to understand these technologies we have to gain a grasp on nanotechnology itself and the different aspects of it that can be applied to medicine.
What is nanotechnology?
If you are like the majority of people, you probably don’t know what nanotechnology is. Nano is a prefix put in front of a unit of measure like with ‘centi’ in ‘centimeter’ or ‘milli’ in ‘milliliter’. The prefix is a way to denote the size of the unit of measure, so something that is a milliliter has a smaller volume than something that is a liter. Same applies for nanometers, which are smaller than
micrometers, but larger than picometers. The graphic to the right visualizes just how small this is. There are many different types of nanomaterials from organic to inorganic to polymeric structures. However, there are a few that are more notable than others in the biomedical field. These types of nanomaterials are either in the early stages of development and testing or, in some cases, already out in the field being used in biomedicines.
Nanotubes
Nanotubes are a group of nanoparticles that are formed into single- or multi-walled structures composed of self-assembling sheets of atoms arranged into tubes (Zdrojewicz, et.al, 2015). They consist of both organic and inorganic compounds. The most relevant of this category in biomedicine are carbon nanotubes (CNTs). They are large, cylindrical molecules built by hexagonally placed carbon atoms and their wall consists of one or more layers of graphene. Due to their high external surface area, CNTs are capable of achieving considerable loading capacity of chemotherapeutics (Zdrojewicz, et.al, 2015). This means that nanotubes, especially CNTs, will be essential in the future of cancer treatments as they have the ability to carry the high loading capacity of anticancer drugs, genes, and proteins needed in chemotherapy.
Nanocrystals
Nanocrystals are drugs formed into crystalline structures at the nanoscopic level. These nanoparticles can be used as a versatile method of improving
the ability of the body to metabolize a drug and a drug to affect the body with
poorly soluble medications (Zdrojewicz, et.al, 2015). This means that drugs that
are normally fairly insoluble and hard to
metabolize can be better used by the body and increases its bioavailability. The crystalline shape that the drug is formed into is the key as to why it is so easy to metabolize. The higher surface
area to volume ratio, especially at the nanoscopic scale, makes the drug that much more soluble and increases its ability to be used by the body.
Dendrimers
Dendrimer’s chemical structure consists of branched, tridimensional polymers that resemble a sphere; the internal structure consists of a multifunctional core and dendrons, which are branches of dendrimers, that fan out from said core (Zdrojewicz, et.al, 2015). The dendrons are capped with free functional groups that might be swapped with a variety of substitutes in order to modify the chemical and physical properties of the structure as a whole (Zdrojewicz, et.al, 2015).
Liposomes
These nanomaterials are described as spherical vesicles with the particle sizes ranging from 30 nm to several micrometers and they consist of one or more lipid bilayers located outside the aqueous units with polar groups headed both towards the exterior and interior aqueous phases (Zdrojewicz, et.al, 2015). These nanoparticles are used to encase drugs and other substances which can be both hydrophobic and hydrophilic to prevent the degradation of their contents and release them for a set purpose. Liposomes have already been implemented as drug carriers in medications such as with analgesics, anticancer and antifungal drugs. The wall of the liposome is selectively permeable and consists of phospholipids, much like with the membrane in a cell. Liposomal nano formulations are currently in the market today for cancer treatments and they have the ability to deliver drugs sequentially and at specific molar ratios within the tumor environment which means optimal treatment use (Ventola, 2016).
Soild Lipid Nanoparticles (SLN)
This final category of relevant biomedical nanoparticles consists of solid lipids stabilized with an emulsifying layer in an aqueous dispersion (Zdrojewicz, et.al, 2015). These nanoparticles promote the improved control over drug release, protect chemically labile and sensitive drug molecules from degradation in external environments and during their passage through the intestines, improvement of the bioavailability of such drugs, using biodegradable and physiological lipids to produce nanoparticles and, with a proper scaling, the low cost of industrial production (Zdrojewicz, et.al, 2015). This is all mostly due to the fact that drug mobility is generally lower in solid lipids than it is within an oily phase.
Current Applications of Nanotechnology in Medicine
Some of the nanoparticles listed above have already been implemented into current medical practice, and have been so for a few years. One example of this is in the field of cardiovascular medicine and involves the formation of a ‘good’ particle of cholesterol. Since cardiovascular disease is ranked the number one killer of Americans, the ability to collect and safely remove plaque deposits could save a countless number of lives (CDC, n.d).
In 2009, scientists created tiny particles in the laboratory that mimic those good cholesterol, scooping it up before it can grow into dangerous deposits of plaque (Eisenberg, 2009). They did this using the power of nanotechnology, because it would be otherwise impossible to create and manipulate such a small particle. The ‘good’ particle that the scientists artificially emulated is called HDL in its natural state, this stands for “high-density lipoproteins” and these particles will circulate the blood much like the artificially-generated ones. Because of their natural tendency to circulate the blood, these HDL particles can be especially useful for imaging (Eisenberg, 2009). There has also been development of HDL-like nanoparticles intended primarily for imaging and diagnosis by Mount Sinai School of Medicine (Eisenberg, 2009). The researchers filled the center of artificial HDL particles with gold and other heavy metals so that their activity can be seen and measured with different imaging technology.
Drawbacks of Nanotechnology in Medicine
Like anything else in life nanomedicine has its drawbacks. A majority of this lies in its scalability and its difficulty to manufacture, however, public opinion also plays a big role in its future. Many people and researchers suggest that we are getting ahead of ourselves, that the excitement and novelty of nanotechnology in medicine is blinding us and preventing us from doing the toxicology research of nanomedicine in order to see its potential harmful side effects (Paddock, 2012).
Conclusions
Nanotechnology can play a huge role in the future of biomedicine. It can completely revolutionize how we treat cancer, cardiovascular diseases, administer drugs and so much more. However, in our pursuit of knowledge and innovation we must remember to take a step back and think out things objectively. We can’t allow the glamor to hide the potential imperfections of nanotechnology and must make sure to properly and thoroughly analyze it.
References
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