Nanomaterials can be a sustainable alternative to combat plant diseases

The use of nanomaterials to combat diseases that affect plants was the subject of a study published in the magazine Nature Catalysis.

The article focuses on the tobacco mosaic virus (TMV), which, in addition to tobacco itself, infects and causes significant losses in tomato, potato and other members of the solanaceae family. But it also describes how nanomaterials can be used to combat other types of viruses, bacteria and fungi in a specific and efficient way.

The research was developed by André Farias de Moura, who is part of the team at the Center for Development of Functional Materials (CDMF), a FAPESP Research, Innovation and Diffusion Center (CEPID) based at the Federal University of São Carlos (UFSCar).

The researcher explains that, in the current scenario, there are several copper-based substances used to combat phytopathogens. An example is Bordeaux mixture, applied to treat fungal infections. Therefore, the investigation began with the choice of an active material: copper sulfide, a substance found in nature and which has a low potential for environmental contamination if used in low doses.

The aim was to discover how to increase the efficiency of copper sulfide so that it works at the lowest concentration possible. The first step was to look at the virus we wanted to combat.

“The tobacco mosaic virus is rod-shaped, with a central cavity along its entire length – about 4 nanometers in diameter. This defines the maximum size that a nanoparticle can have to enter the virus and attack it from the inside. This size control does not occur, for example, in the preparation of Bordeaux mixture, in which a copper salt, lime and water is simply mixed, so that all the particles end up being larger than the size we want to obtain”, explains the researcher.

The strategy was, based on these observations, to add a molecule that controlled the size of the nanoparticles as they were formed, which in this case was achieved with the addition of the amino acid penicillamine.

Moura says that the technique proved to be very effective and made it possible to obtain a material that inactivates the virus with very low concentrations of copper, in the order of 10 thousand times less than in Bordeaux mixture. So low that it can be comparable, for example, to the concentration of copper in water that comes from domestic solar heating.

“We hear a lot about precision medicine, in which each person will have treatment with personalized medicine in the future. This customization means finding the most effective medicine for the specific disease you want to treat and with the minimum number of side effects. What we demonstrate in this study is that this same idea can be applied to agriculture. We show how it is possible to treat a disease with a chemical pesticide that is practically harmless to the plant and the environment, but very efficient. This same philosophy can be applied to any disease caused by viruses, bacteria or fungi – just optimize a nanomaterial for each case”, comments the professor at UFSCar, who coordinates a the project financed by FAPESP.

The group of researchers that Moura is part of is finalizing the investigation of a new copper sulfide nanoparticle, also chiral, but with a different shape and size, and which has been shown to be active against SARS-CoV-2. This shows how it is possible to take advantage of learning from an investigation to accelerate advances in related topics.

The article Site-selective proteolytic cleavage of plant viruses by photoactive chiral nanoparticles can be read by accessing here.