Nanoparticles are very small materials, on the order of nanometers (a million times smaller than a millimeter). To give you an idea, they are about 5,000 times smaller than a grain of sand.
British museumCC BY
Although talk of nanoparticles sounds futuristic, already in ancient Mesopotamia (9th century BC) potters used them to add color to their works and achieve various optical effects. Until the 19th century, there was no scientific description of the optical properties of nanometals, provided by the British physicist Michael Faraday. In the 20th century, in the 70s, the term was finally coined. nanoparticle.
These tiny materials are now used in fields as diverse as cosmetics, environmental restoration, and healthcare. This is how nanomedicine was born – a branch of medicine that applies the knowledge and tools of nanotechnology to diagnose, prevent, and treat diseases.
Among the diseases that are in the spotlight of nanomedicine is cancer, one of the leading causes of death worldwide. It is estimated that one in five people suffers from this pathology during their lifetime, resulting in the death of one in nine men and one in twelve women.
The most commonly used methods of cancer treatment are surgery, chemotherapy and radiation therapy, but each of them has its own disadvantages. For example, not all tumors can be operated on due to their location, as is the case with pancreatic tumors. In addition, radiotherapy and chemotherapy are non-specific, that is, they affect both tumor and healthy cells, causing many side effects.
To improve this scenario, science is developing innovative treatments such as nanoparticle-based treatments.
Vehicle for transporting medicines
When drugs are absorbed, they enter the bloodstream where they circulate. Being small in size, a significant amount escapes from the vessels and accumulates in healthy tissues. Another important part is excreted through the liver and kidneys, causing long-term damage to these organs.
Given that some of the drug administered does not reach the tumor areas, the doses administered are usually high to ensure that the target is reached, which ultimately turns out to be toxic to the body.
How can tiny particles help us solve these huge problems? Although nanoparticles may seem small, they are large enough to encapsulate drug-sized molecules, such as chemotherapy agents, inside them. This allows them to be protected like armor, increasing their retention in the bloodstream and reducing both side effects on healthy tissue and their early elimination.
Given that all or almost all of the compound reaches the tumor site, this strategy allows for a reduction in the administration dose and hence toxicity without reducing the therapeutic effect.
Straight to the target
In addition to serving as a drug carrier, nanoparticles act as a carrier with a clear target: the tumor area. But how they know Will these nano-vehicles reach their destination?
In order for tumor cells to grow faster than healthy cells, they require a larger supply of nutrients and oxygen. They do this by emitting the necessary signals to synthesize new blood vessels around the tumor. These vessels are different from those that irrigate healthy tissue because they have windows or cavities through which everything that passes through the blood and passes through them exits.
Once a drug encapsulated in nanoparticles is injected into a patient, it travels through the bloodstream until it reaches the tumor site. Through the windows of these special vessels, the nanoparticles can exit the bloodstream, accumulating in the tumor. This process is known as passive drug delivery.
We can improve the delivery of a chemotherapeutic agent to a tumor by actively targeting it. It works like this: all the cells in our bodies have a series of molecules on their surface that provide identity, like a license plate or an ID card. These molecules vary depending on the type of cell; for example, the cells that make up our skin have different molecules on their surface than those in our neurons, and also different from those that characterize tumor cells.
Using this phenomenon as a strategy, molecules capable of recognizing and binding to tumor cells can be incorporated into the surface of nanoparticles, like a dart aiming at its target.
The first nanopreparations have appeared
In 1995, the first nanodrug called Doxil entered clinical practice. This drug, based on the use of nanoparticles as a carrier of the drug Doxorubicin, is used in the treatment of ovarian cancer, Kaposi’s sarcoma and multiple myeloma.
Although approval of a new drug is a slow and complex process, more than 70 nanomedicines have already reached patients, and about twice as many nanomedicines are currently undergoing clinical trials. Although most are anti-cancer, nanomedicines are also marketed for other purposes, such as treating autoimmune, neurological, or inflammatory diseases.
These little soldiers even fought the global Covid-19 pandemic, serving as a tool for the creation of the Pfizer/BioNTech and Moderna vaccines.
Conclusion
Throughout history, humans have always known how to use nature’s resources to meet their needs. The use of nanoparticles in medicine has proven to be a key strategy for improving the quality of life of patients, as it represents a bridge between traditional treatments such as chemotherapy and modern treatments based on specific and personalized therapy.
As Spanish Nobel laureate Severo Ochoa said:
“Science is always worth it because its discoveries are always applied sooner or later.”
This article was a finalist in the IV Youth Outreach Competition organised by the Lilly Foundation and The Conversation Spain.