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Materials engineering

The power of copper

Copper nanoparticles can be used to create biocidal fabrics and agricultural pesticides

Copper nanoparticles in powder form produced by the Cecil Group and IPT

Léo Ramos Chaves

Copper, a mineral with proven antimicrobial properties, has shown potential for use in more technologically elaborate products with a higher market value. Studies by startups and universities show that when used in nanoparticle form, the mineral can be incorporated into fabrics, paints, and plastics, offering protection against viruses and bacteria. It also has potential for use as an ingredient in poultry and swine feed to replace antibiotics, and in combating agricultural pests, emulating the role of conventional pesticides.

One of the most advanced studies is led by the Cecil Group, which operates in the metal laminates sector, and the São Paulo State Institute for Technological Research (IPT). At the end of 2020, the two partners filed a patent application for a production process that uses Brazilian technology to obtain copper nanoparticles. Research on the process began in 2018 and grew even more relevant with the arrival of the COVID-19 pandemic. Copper additives could help stop SARS-CoV-2 contamination. Upon coming into contact with the microorganism, the mineral breaks its outer membrane, leading to its destruction. A doorknob or a handrail coated with paint containing copper would thus kill the virus, minimizing its spread via hand contact.

Looking to gain a greater share of the market, the Cecil Group set up a new company called Abluo specially to design and develop technological solutions using this new material. The idea is for new technological solutions to be created based on the demands of the startup’s clients and in partnership with them. “With Abluo, we started to invest not only in commodities, but also in high-value materials, such as fabrics containing additives,” highlights Clayton Lambert, head of innovation and technology at the Cecil Group.

Copper nanoparticles, in liquid or powder form, can be used in hospitals, construction, the automobile industry, the textile sector, and many others. They are obtained by subjecting copper sulfate to a chemical reaction called oxidation-reduction (redox) and encapsulating the active element—protecting the nanocopper with a special coating. Biologist Patrícia Léo, technical manager of the Industrial Biotechnology Laboratory at IPT, explains that the nanoencapsulation process was found as a way of circumventing one of the biggest challenges faced when working with copper: its instability. “The nanoparticles created by the redox reaction are unstable and tend to agglomerate. To make them more stable, we created coatings using polymers and surfactants,” explains the researcher.

The Cecil Group and IPT are improving the manufacturing process in an effort to increase production scale. Léo explains that initially, a batch production process was used. “The reagents are placed into a reactor tank in a specific order, like the ingredients of a soup,” she says. “The amount produced per batch is limited by the size of the tank.” This limit can be overcome with the use of microfluidic reactors, a process being developed by IPT. “Microreactors operate in a continuous flow, without interruption,” explains the scientist. The new process is more precise and makes the nanoparticle sizes more homogeneous, which may increase their biocidal potential.

The partnership was established three years ago when the Cecil Group decided to create a product that would utilize the natural biocidal properties of copper, funding Pedro Paulo Noronha Silva de Jesus and Rúbia Rodrigues Conti, both students on IPT’s professional master’s program. Their research resulted in the now patented technology and earned them both jobs—Jesus works at Abluo and Rodrigues at IPT.

Léo Ramos Chaves Synthesis of nanocopper at IPT: copper sulfate pentahydrate solution, coating agent, reducing agent, and liquid copper nanoparticle solution (from left to right)Léo Ramos Chaves

Our growing knowledge about the novel coronavirus, which we now know spreads via the air more than through contact with contaminated surfaces, does not reduce the number of potential applications of the new product, say the researchers. “Every form of prevention is important. Copper nanoparticles can be used in air conditioning ducts and filters,” points out Léo.

Elson Longo, a chemist and professor at the Federal University of São Carlos (UFSCar) and director of the Center for the Development of Functional Materials (CDMF), one of the Research, Innovation, and Dissemination Centers (RIDCs) funded by FAPESP, agrees. “This is a field that is going to grow exponentially. The vaccine provides some immunity, but it is still important to wear a mask, wash hands, and protect places used by many people, such as bus seats, door handles, turnstiles. This protection will remain critical in the future.”

One subsidiary of the CDMF is Nanox, a startup that specializes in silver nanoparticles. The antimicrobial nanoparticles, created with funding from FAPESP’s Research for Innovation in Small Businesses program (RISB, or PIPE in Portuguese; see Pesquisa FAPESP issue 288), has already been applied to various materials, such as paper, plastic, and textile fibers. Copper nanoparticles, according to Longo, offer this market more options.

Green substitute
Brazilian Nano Feed (BNF), a startup from Santo André, São Paulo State, is also working with copper nanoparticles. With funding from FAPESP, the company is synthesizing copper and silver nanoparticles to use as additives in swine and poultry feed. The goal is to replace the antibiotics currently used to reduce pathogenic bacteria in the intestinal tracts of the animals and facilitate the absorption of nutrients.

“Indiscriminate use of antibiotics leads to resistance,” explains veterinarian Joaquim Gonçalves, commercial manager at BNF. The company has already formulated a product that can be incorporated into different types of feed. Camila Neves Lange, founding partner of the startup, highlights the advantages of using copper and silver together in the same additive. “Copper is more difficult to work with, but it is cheaper and a nutrient that is already widely used, while silver has a more efficient bactericidal effect,” she says. The next step will be to conduct field trials with farmers to compare the effectiveness of antibiotics versus the copper and silver nanoparticles.

Researchers at the Federal University of ABC (UFABC) are investigating the use of copper nanoparticles to replace conventional pesticides in agriculture. “We are using the material to combat plant pathogens and to stimulate biofortification. Copper is an important element for plant growth,” highlights Amedea Barozzi Seabra, a chemist funded by FAPESP.

The researcher is also using silver nanoparticles in a project that aims to eliminate post-harvest fungi. In this study, in partnership with the Agronomic Institute of Campinas, Seabra coated the nanoparticles with chitosan, a natural and biodegradable polymer, modified to release nitric oxide. “This element also has bactericidal properties. Together with the silver nanoparticles, it allows us to use less of the metal,” explains the researcher, who has already applied to patent the technology.

1. Synthesis of nanostructured copper and silver complexes to replace growth-promoting antibiotics in swine and poultry farming (nº 20/00766-7); Grant Mechanism Research for Innovation in Small Businesses (RISB/PIPE); Principal Investigator Camila Neves Lange (Brazilian Nano Feed) Investment R$184,923.00.
2. Essential oil containing metal nanoparticles functionalized with nitric oxide as a strategy to control plant pathogens in agriculture (nº 18/08194-2); Grant Mechanism Regular Research Grant; Principal Investigator Amedea Barozzi Seabra (UFABC); Investment R$219,784.78.

Scientific article
KOHATSU, M. Y. et al. Foliar spraying of biogenic CuO nanoparticles protects the defence system and photosynthetic pigments of lettuce (Lactuca sativa). Journal of Cleaner Production. Vol. 324. Nov. 15, 2021.