Metal-Organic Frameworks: The Latest in Cancer Therapy
Finding the cure to cancer is one of the biggest challenges that modern scientists face. Over the past few decades, many drugs and cancer therapies have been developed. However, most of them have horrible side effects. Many therapies kill both cancerous and healthy cells, causing side effects such as hair loss, a weakened immune system, and overall poor health. To combat this problem, scientists are trying to find cures that target cancer cells alone. One of the methods that scientists are testing is using 3-D structures called metal-organic frameworks (MOFs). Scientists can use MOFs in multiple ways, with the most prevalent being a) engineering MOFs to respond to certain cancerous factors or b) programming MOFs to recognize the specific markers on cancer cells.
Before explaining how MOFs are used, it is important to examine why MOFs are used. MOFs are 3-D, net-like structures that can be made on the nano-level, which is essentially a billionth of a meter (1). Metal ions act as knots that are linked together by inorganic compounds. This structure is repeated many times, creating a net-like structure filled with holes. Tens of thousands of MOFs have been discovered and made so far (2). The variability of MOFs comes in the different ways they can be created. The metal ions and inorganic compounds used in the structure can be varied, as can the method of creation. These options allow for great diversity in the types of MOFs that can be made. The variability in building materials also leads to variability in function, so MOFs can be used to solve many real-life problems, such as global warming and renewable energy capture.
The characteristics described above are the reason that MOFs are used as drug carriers. The nanosize of MOFs allow them to be easily introduced into the human body. The porous nature of a MOF increases the ratio of its surface area to its volume. More importantly, the holes in MOFs enable them to carry particles both inside them and on their surface. Finally, depending on the type of MOF that is made, MOFs can change their structure based on external factors such as pH levels, ion concentration, geomagnetic factors, and more (3).
The first method of drug delivery with MOFs is to make them with materials that can respond to cellular factors. A study published in the Journal of Materials Chemistry describes the steps taken for this method. First, a MOF with pores large enough to incorporate the drug has to be made. Then, the drug has to be loaded in the MOF through multiple steps. The MOF is then introduced into the bloodstream, and breaks down when it reaches an area of low pH. Low pH is the cellular factor that the MOF responds to (3). The reason why this is important is because cancer cells generally acidify their environment, lowering the pH. So, some researchers theorize that if a MOF can break down only when it reaches an acidic environment, but can carry an anticancer drug until then, it can successfully act as a targeted drug delivery vehicle to cancerous regions.
The second method is to program the MOF so that it can recognize cancer cells and release its cargo in their vicinity. Every cell has markers on their surface to communicate and signal with other cells. Likewise, cancer cells also have unique markers. The MOF would be engineered with a receptor to a cancer cell’s unique marker. When a MOF encounters a cancer cell with the specific marker, it binds to it and releases the drug (4). These two methods have been advocated for by chemists and oncologists across the world. Everyday, new research in the field of MOFs is being performed, bringing scientists a step closer to a possible cure for cancer.
References:
1. Woodford, C. (2020, September 01). Nanotechnology: A simple and fun introduction! Retrieved November 20, 2020, from https://www.explainthatstuff.com/nanotechnologyforkids.html
2. New state-of-the-MOF materials. (2020, February 28). Retrieved November 20, 2020, from https://www.eurekalert.org/pub_releases/2020-02/ku-nsm022820.php
3. Wang, Lei, et al. “Nanoscale Metal–Organic Frameworks for Drug Delivery: a Conventional Platform with New Promise.” Journal of Materials Chemistry B, vol. 6, no. 5, 2018, pp. 707–717., doi:10.1039/c7tb02970e.
4. Cai, Mengru, et al. “Metal Organic Frameworks as Drug Targeting Delivery Vehicles in the Treatment of Cancer.” Pharmaceutics, vol. 12, no. 3, 2020, p. 232., doi:10.3390/pharmaceutics12030232.
