Gold nanobots are a well-known material with optical properties useful for application in the treatment of diseases such as some cancers in so-called photodynamic therapy. Scientists from Brazil, the United States, and China have shown that these nanostructures, when combined with molecules that correspond to the proteins present in our bodies, can help better understand, diagnose, and seek out new therapies for a wide variety of diseases.
The researchers combined the nanoribbons with synthetic peptides – small proteins identified by the acronym hIAPP – which are very similar to the peptides found in the healthy human body, but altered the cause of diseases as diverse as pancreatic cancer, type 2 diabetes, Alzheimer’s and Parkinson’s are. The change is due to the change in the conformation of these molecules and their resulting aggregation, which forms so-called amyloid plaques, which prevent neurons from functioning properly in people with Alzheimer’s or Parkinson’s, for example.
In humans, as well as in animal models used in drug development tests, these plaques can take months or years to form. The interaction between gold nanoribbons and peptides accelerated this process, which has now been mimicked in the laboratory in a few hours. This also makes it quicker to test which drugs can inhibit plaque build-up and thus may be useful in treating diseases.
Another result was the identification that the interaction with the peptides changed the way the material absorbs and emits light, leading to a property called dichroism, namely the ability to interact with a specific form of light, the circular is polarized. The synthetic peptide has an affinity for the peptides present in our body, and the interaction with light is different depending on whether the synthesized material finds isolated peptides (with a helix structure), which are typical for healthy tissue, or aggregated molecules in the form of Fibers or plaques (the structure of which is called a flat sheet and is associated with the development of diseases).
“The study showed the possibility of precisely identifying whether the peptides are in the form of a helix or a flat sheet, and this opens up the prospect of an early diagnosis before the onset of the disease, also because the detection is also in very low concentrations. ” explains André Farias de Moura, professor at the Department of Chemistry at the Federal University of São Carlos (UFSCar), who is responsible for the Brazilian part of the research. Other advantages, explains the researcher, are that the light emitted is so intense that it can be measured with devices as simple as a cell phone camera, and that the synthesized nanostructures interact with the light in the infrared range, which allows you to observe what happens in tissues or even organisms with a minimum of interference from other molecules.
“The article shows that we can develop platforms to search for and screen for new drugs, not only faster, but also more precisely, because we can examine the affected tissues directly and not in test cultures, for example tubes,” explains Moura.
He also explains that the synthetic model of the developed material can serve applications in scenarios that are currently not even imaginable. “It’s like vaccines against the new coronavirus. If basic research developed long before we imagined that the pandemic’s incidence couldn’t be adjusted quickly, we wouldn’t get to vaccines in less than a year, ”he compares. “If we can modify our platform in such a way that it detects the spike proteins or antibodies against Sars-CoV-2 rather than the peptide, it is possible, for example, to test new drugs and to accelerate the accuracy of the diagnosis increase and including inactivation of the virus, ”he predicts.
The research article entitled “Improving Optical Asymmetry in Long-Range Supramolecular Chiroplasmonic Arrays” was published in Science today. The research in Brazil was funded by the University Staff Improvement Coordination (Capes), the National Council for Scientific and Technological Development (CNPq) and the São Paulo State Research Support Foundation (Fapesp) in addition to using the resources of the Santos Dumont supercomputers. Partners in other countries are the University of Michigan, USA, and Jilin University, China.
Check out a video in which André de Moura presents his work.