Monday, October 13, 2014

Supramolecular Chemistry in Drug Discovery

Contributing writer Lily Bryant

Supramolecular chemistry has important medical applications, as it aids the development of new drug therapies by helping researchers to understand how medications interact at the target binding sites in the body. This area of chemistry has also aided the development of binding drugs that are able to alter the target substance and its properties, so the substrate is unable to reach its action site or trigger the usual biological response. Examples of this are the phosphate binding drug sevelamer hydrochloride, which is used to manage raised phosphate levels in advanced cases of chronic kidney disease, and the selective binding agent sugammadex, which reverses neuromuscular block brought on by vecuronium and rocuronium during anesthesia. However, supramolecular chemistry is also important for the development of drug delivery systems, which offer encapsulation and targeted release.

Researchers from Lawrence Berkeley National Laboratory have recently made a development that will hopefully pave the way to more effective and safer drug delivery systems. These systems can help to reduce the unwanted side-effects associated drug therapies, which are sometimes severe enough to discourage patients from accepting medication or mean that they have to abandon treatment. As with opiate based painkillers, the untargeted nature of their actions means that some drugs may even lead to addiction. While intrathecal delivery of painkillers can help those people struggling with chronic pain that is difficult to control, it isn’t without its risks and more precise targeting of drugs with the aid of molecular delivery systems could offer more successful results without the adverse effects.

The team which previously developed peptoid nanosheets that come together where air and water meet have now created peptoid nanosheets that come together where oil and water meet. If you are not familiar with the concept of a peptoid nanosheet, this is a synthetic 2D protein structure, which typically has a thickness of just three nanometers, making it one of the thinnest organic 2D crystalline materials available. Just like natural proteins, peptoids are able to fold and curve into specific shapes, enabling them to complete precise functions. As it is possible to customize the peptoids from which they are formed, this makes the properties of these nanosheets flexible, meaning that they are a good candidate in the area of drug delivery. Additionally, the very large surface area of peptoid nanosheets makes them ideal for sensing and recognition, which is again vital for drug delivery. Another useful property for these applications is their hydrophobic core, which excludes water molecules, meaning that peptoid nanosheets have the potential to carry hydrophobic cargos, as demonstrated by research published in ACS Nano. Finally, peptoids are not as sensitive to chemical or metabolic changes as proteins, so they are less likely than natural proteins to break down, which is advantageous when using them within the body.

The latest findings, which were published in the September edition of the Proceedings of theNational Academy of Sciences USA, show how it is possible for these specific and highly organized peptoid sheets to form at a water-oil interface. Spectroscopic measurements confirm that the monolayers are extremely well ordered and that it is the electrostatic action between charged molecules on the peptoid that allow the formation of this orderly structure at the surface of oil and water. The ability to create these nanosheets using oil instead of air creates new possibilities for their production6. It would also allow the development of libraries of various functionalized nanosheets and allow screening for peptoid nanosheets that have the same molecular recognition as specific proteins, which would aid future drug discoveries. While the production of peptoid nanosheets with drugs in their interior is still some way off, these findings open up the possibility of extending the complexity and functions of 2D nanomaterials, which can only aid the development of drug delivery systems.

About Lily Bryant

Lily Bryant is a writer working with one of only two licensed online pharmacies in the US. She is strongly interested in promoting and creating content aimed at relevant readers as part of her role in ethical healthcare business. She believes that it is important that we play a strong role in leading society towards a healthier lifestyle through the promotion of exercise and healthy diet rather than an early adoption of drug treatment.

Tuesday, September 23, 2014

Old wisdom new tools

Some of the shapes depicted in ancient artefacts that were invisible to the human eye came into view with the advent of 20th century tools. Some being nano and microstructures. These tools also help chemists to see the formation of chemical bonds in real time.

The rapid development of modern nano-technological tools such as the Atomic Force Microscope (AFM), Scanning Tunnelling Microscope (STM) and Laser Scanning Confocal Microscope (LSCM) allow scientists to invent, explore and validate old scientific discoveries. From the perspective of scientists involved with chemistry, it helps to manipulate atoms and molecules precisely for the fabrication of macro scale products as well as to look at the real time covalent bond formation in a single molecule. Observing chemical reactions by force microscopy at sub molecular resolution has been reported by de Oteyza et al.  They reported  the atomically resolved imaging of a complex molecule as it undergoes a chemical reaction on a metal surface.

In addition to the normal covalent bond formation, very recently Wilson Ho, revealed the image of hydrogen bonding in porphyrin molecules using chemically modified STM tip, enlightening  us with the rapid advance in this field. These developments will have a huge impact in nanoscience especially in the field of single molecular electronics and bottom up fabrications. This new evolution of molecular nanotechnology will bring chemists, physicists, engineers and biologists together.

How practical is it to prove old theoroes with morden, technologically advanced tools? Is it really possible? However, if it is indeed possible, would it be a landmark achievement that would push chemistry into a new era, in the coming years? Let me exemplify. Mayan blue is a bright blue pigment that had been used by Mayans about 2000 years ago to paint murals. The distinct feature about these murals is that the mayan-blue has withstood the wrath of weather over centuries, and refuse to fade even to this day. Whereas, on the other hand, even the most advanced of paints of today, tend to wear off after a couple of years of harsh weather and negligent maintenance. This is a phenomenon that has baffled the scientists for several years. They were able to gain some insight into this in the recent past with the help of modern nano technological tools. The Mayan dye is based on Indigo dye, which is trapped in a porous fame work of clay called palygorskite.  The silicate hull forms a protective layer around the dye molecules. This prevents the dye pigments from directly interacting with the forces of nature, and other interferences such as organic solvents, acid and alkali treatment etc.

             It is the mayan’s ingenuity at developing the pigments for mayan blue that has set them eons beyond out reach. Reverse engineering this could help us understand its structure and shed some light into the properties of advanced hybrid materials. May be, the day is not far off, when we are able to decode this chemical phenomenon and come up with commercial paints that will last forever.