B-MRS live on materials research and COVID-19.

B-MRS live gathered 4 panelists from different points of the country  and around 100 participants.
B-MRS live gathered 4 panelists from different points of the country and around 100 participants.

In several Brazilian universities, multidisciplinary scientific teams are currently working to deliver to society, in the shortest possible time, solutions to help combat COVID-19. Beyond generating publications, and even knowledge, the main objective of these works is to save lives.

The materials research community is actively participating in some of these challenges, which could generate important solutions such as rapid, reliable diagnostic tests and virucidal materials for ventilator valves, as well as personal protective equipment (PPEs) produced in Brazil.

In the early afternoon of May 7, in its first live transmission, B-MRS brought together four researchers who are working on these challenges. These scientists told an audience of about 100 how they organized to respond to this emergency situation, and what may be the social impact of their projects. The reports showed the importance of continuous investment in research and collaboration between individuals and institutions.

The discussion was mediated by Carlos César Bof Bufon, researcher and head of the Devices Division at the Brazilian Nanotechnology Laboratory (LNNano/CNPEM). Bufon is part of the organizing committee of the next annual B-MRS event, the XIX B-MRS Meeting.

The online discussion panel, broadcasted on B-MRS’s Zoom platform and Facebook, was held within the Brazilian Virtual March for Science, an event promoted by Brazilian Society for the Progress of Science (SBPC) with the aim of calling attention to the importance of science.

National tests for COVID-19 diagnosis and detection of antibodies.

The scientists Mariana Roesch Ely (professor at the University of Caxias do Sul, UCS) and Talita Mazon (researcher at CTI Renato Archer) talked about their respective works to develop sensors for COVID-19 diagnostic tests, which they are carrying out with the support of specialists in the Chemistry, Electronics, Informatics, Physics, Materials, Biology and Health areas.

Both sensors are point-of-care instruments. This expression designates miniaturized devices that allow performing tests anywhere, without the need for laboratories or other equipment, and receiving the result within a few minutes.

According to the researchers, the sensors they are developing will be able to detect those infected with COVID-19 within the first day of infection – a characteristic that none of the diagnostic techniques currently used in the country allows. Finally, they said that the new sensors will provide more accurate results (with fewer false negatives or positives) than many of the rapid tests that are currently available on the market.

In both works, the development of the sensors is quite advanced. However, the two scientists concur in stating that 6 months is a reasonable time for a product to be ready, tested with respect to the RT-PCR method (the most reliable at the moment) and viable at an industrial scale.

In her statement, Professor Mariana said that since 2012 she has been working on developing sensors based on magnetoelastic technology, initially aimed at the detection of bacteria and yeasts. When Brazil experienced the outbreak of the Zika virus in 2015, the scientist and her entire research network directed their work towards this virus, gaining experience in detecting this type of organisms, which are much smaller than bacteria. According to Professor Mariana Roesch Ely, the magnetoelastic sensor would be able to detect both the viral particle (from the beginning of the infection) and the antibodies produced by the person who is or has been infected. Thus, it could be an important tool to define measures and protocols in all phases of the pandemic, including the resumption of face-to-face economic activities.

Researcher Talita Mazon said that she has worked five years on integrating ceramic and biological materials to develop point-of-care sensors, which, in her view, are well adapted to the Brazilian reality, given that a large part of the population lives far away from laboratories and hospitals. With the experience accumulated during that time, the scientist was able to finalize in 2019, together with a multidisciplinary team, an electrochemical sensor that detects the Zika virus accurately and within a few minutes. She is currently adapting this platform to detect Sars-COV-2 (the virus that causes the COVID-19 disease).

Thinking about the possibility of producing the sensor without the need for imported inputs, mainly at an industrial scale, the researcher looked for local partners and adapted the sensor to the biological inputs that could be produced in Brazil. In addition, she is establishing a partnership with the public microelectronics company CEITEC, located in the state of Rio Grande do Sul, whose installed capacity would allow it to manufacture the chips for all the sensors needed to test the Brazilian population in the next phases of the pandemic. “We have to join forces to develop solutions that can actually be met by the country’s industrial capacity,” said Professor Talita Mazon.

Virucidal materials for masks and respirators

In the panel, Dachamir Hotza, professor at the Federal University of Santa Catarina (UFSC), told of the individual and group efforts carried out to bring responses to society during the COVID-19 pandemic. In one of these works, the researcher and his collaborators are carrying out the physical and biochemical characterization of masks used in hospitals in order to define precisely when the masks lose their functionality and need to be replaced. In addition, working with other institutions and a regional company he previously collaborated with, the researcher is advancing in the development of fabrics with virucidal activity. One difficulty that has not yet been overcome, said the researcher, was accessing a laboratory that has the appropriate level of biosafety procedures to perform tests with the new coronavirus.

Active materials in the elimination of the Sars-COV-2 virus were also addressed by Professor Petrus Santa Cruz, from the Federal University of Pernambuco (UFPE). The scientist told how he accumulated knowledge generated over decades, available in articles and patents from his research group, for his work related to fighting the pandemic. One example relates to an emergency action aimed at providing the public health system with respirator valves that could be used in patients infected with COVID-19 in a phase prior to intubation, given situations of high occupancy rates of ICU beds and mechanical ventilators. Professor Petrus’ interdisciplinary team, which includes software experts, was able to overcome the challenge of manufacturing these valves on 3D printers with the necessary surface roughness to prevent the bacterial adherence (initially bacteria and, probably, also viruses). In addition, the group is working to give this and other materials an active role in eliminating the virus, using nanotechnology to break through the wall that protects the viral RNA.

Continuous investments for fast results

The four panelists highlighted that the capacity of science to quickly respond to society in times of emergency is the result of many years of efforts and investments. “There is no on/off button for science, because it is made up of the accumulation of knowledge,” said Professor Petrus.

On the other hand, with successive cuts to the CTI budget, many Brazilian researchers have developed strategies to circumvent the difficulties and continue working. It is a characteristic of the Brazilian scientist to adapt to adverse situations, commented Professor Dachamir.

The panelists’ statements showed that a combination of expertise and persistence, on the one hand, and creativity and reinvention, on the other, is part of the method they are applying in their work related to fighting the pandemic.

Another aspect the scientists highlighted as fundamental to the success of emergency projects was the work in multidisciplinary collaborative networks, including with companies that could produce solutions at an industrial scale. “This is the time to intersect everyone’s expertise to give a quick response to society,” said Professor Mariana Roesch Ely.

Featured paper: Conductive cotton thread for sewing wearable electronics.

SEM image of a conductive thread.
SEM image of a conductive thread.

The “old-fashioned” sewing thread universally used, for example, to sew buttons, has recently been transformed by a Brazilian scientific team into an electrically conductive and multifunctional material. In fact, the various uses of this new sewing thread go far beyond sewing. It works very well as a mini electric heater, as a component of supercapacitors (devices that store and release energy, similar to batteries) and as a bactericidal agent. In addition, the thread is flexible and comfortable to the touch, and retains its electronic properties even after being washed, twisted, curled or folded repeatedly.

With these characteristics, this fiber can play an important role in wearable electronics – the set of electronic devices designed to be worn on the human body, incorporated into clothing or accessories.

“As the thread is a basic element for the design of textiles, we imagine that any wearable product can make use of this technology”, says Helinando Pequeno de Oliveira, a professor at the Brazilian Federal University of the Vale de São Francisco (Univasf) and leader of the scientific team that developed the conductive and bactericidal thread. Together with three other authors, all linked to Univasf, Oliveira authors an article reporting this work, which was recently published in the journal ACS Applied Materials and Interfaces.

The conductive  and bactericidal fiber of Oliveira and his collaborators is made of a composite material: cotton thread of 0.5 mm diameter, coated with carbon nanotubes and polypyrrole. The resulting material presents, in addition to high electrical conductivity, good electrochemical activity – necessary characteristic for it to be used in supercapacitors.

To make the conductive  fiber, the Univasf team developed a very simple process, formed by two main stages. In the first step, pieces of cotton thread are submerged in a paint of carbon nanotubes, previously modified in order to increase their interaction with the cotton. As a result, the thread is coated by a continuous network of interconnected nanotubes.

The second step is intended to coat the fibers with a second material: polypyrrole. To do this, a solution is initially formed by pyrrole and the solvent hexane, in which the fibers coated with nanotubes are submerged. Thereafter, another solution is poured over this preparation. The second solution consists of water and some compounds, which will be incorporated in very small amounts into the chemical composition of the polypyrrole in a process called “doping” of the material. At the interface between both solutions, which do not mix, the small pyrrole molecules are bound together, resulting in the formation of polypyrrole macromolecules that are deposited on the surface of the fibers. This process, in which a polymer forms at the interface between two solutions, is called “interfacial polymerization”. “Given the good polypyrrole doping level (optimized for this synthesis) and its strong interaction with the functionalized nanotubes, the resulting fibers display excellent electrical properties,” says Professor Oliveira.

The scientific team also produced some variants of this sewing conductive  thread. For example, a fiber without carbon nanotubes and another fiber whose polypyrrole coating was produced by means of non-interfacial polymerization. However, the lines with carbon nanotubes and interfacial polymerization showed the best electrical and electrochemical performance.

Heaters and supercapacitors made of cotton fibers

First and second generation supercapacitor prototypes based on conductive sewing lines.
First and second generation supercapacitor prototypes based on conductive sewing lines.

“The high electrical conductivity (together with the good porosity of the material) made of the material a great prototype for application in electrodes of supercapacitors”, says Oliveira. “These properties also made it possible to use it as an electric heater with very low operating voltages (of the order of a few volts). In addition to these applications, the antibacterial potential of the matrix”, he adds.

In addition to testing the performance of the conductive and bactericidal fiber in isolation in the laboratory, Oliveira and his collaborators developed a proof of concept. “We used a needle to sew the thread in a glove”, says the professor. With this we could monitor the temperature that the hand, wearing this glove, would reach when we connected the device to a power supply,” he explains.

The heating system tested on the glove can be adapted to a variety of contexts, such as an ambulatory version of thermotherapy (therapeutic heating of body regions, which is often used in physiotherapy sessions)with the added advantage of antibacterial action. This property is particularly interesting in materials that are used in contact with the skin, since, in this way, they avoid diseases and odors. In the case of polypyrrole, the action occurs when the material electrostatically attracts the bacteria and promotes the breakdown of its cell wall, inhibiting its proliferation.

Local heating (in degrees centigrade) provided by the conductive thread sewn to the index finger of the glove, after applying an electric voltage of 12 V.
Local heating (in degrees centigrade) provided by the conductive thread sewn to the index finger of the glove, after applying an electric voltage of 12 V.

A possible wearable product based on the conductive sewing thread is a thermal jacket.It could be powered by a solar cell incorporated into the jacket, or by means of triboelectric devices, which would reap the energy generated by the user’s movement of the jacket.The resulting energy would be stored in a supercapacitor made with the conductive fiber. Tailored to the jacket, the supercapacitor would provide electricity to the heater when needed.
Another example is the energy storage t-shirt, in which Professor Oliveira’s group is currently working to generate a marketable product. We are currently optimizing the production of supercapacitors in pieces of cotton and lycra fabrics as a way to connect them directly to portable power generators, thus enabling the development of energy storage t-shirts,” says Oliveira.

Science and technology developed in the backlands

The work reported in the ACS Appl. Mater. Interfaces and their developments were fully carried out at the Materials Science Research Institute of Univasf, on the campus of the municipality of Juazeiro, located in the north of the state of Bahia. Univasf, which has six campuses located in the interior of the states of Bahia, Pernambuco and Piauí, was created in 2002 and inaugurated in 2004. In the same year, Oliveira became a professor at the institution.

The development of the conductive cotton lines was born from a thread of research on electronics and flexible devices, created in 2016. In 2017, the idea became the theme of the master’s work of Ravi Moreno Araujo Pinheiro Lima, guided by Professor Helinando Oliveira, within the Postgraduate Program in Materials Science at Univasf – Juazeiro, created in 2007. Post-doc José Jarib Alcaraz Espinoza, who was optimizing syntheses of conductive polymers for supercapacitors, adapted a methodology to interfacial polymerization in cotton. With this, the researchers realized that the conductor lines worked as good supercapacitor electrodes, and fabricated these devices. At the same time, with the collaboration of Fernando da Silva Junior, a doctoral student of the institutional postgraduate program Northeast Network of Biotechnology, the team tested the action of the material against the bacterium Staphylococcus aureus, responsible for a series of infections of varying degrees of severity not human.

“These results reflect Brazil’s investment in the internalization of its network of federal teaching and research institutions. With this, the migration of the sertanejo towards the great capitals in the search for knowledge has been reduced. Now there is also more science being produced in the northeastern backlands”, says Professor Oliveira. “However, recent cuts in S & T have launched a huge cloud of uncertainty about the future of science in the country (and in particular about these young institutions). The Brazilian government does not have the right to throw so many dreams in the trash. Science needs to overcome this crisis,” completes the researcher.

Photo of the research group led by Professor Oliveira at the Institute for Research in Materials Science. To the right, in blue, the authors of the article.
Photo of the research group led by Professor Oliveira at the Institute for Research in Materials Science. To the right, in blue, the authors of the article.

[Paper: Multifunctional Wearable Electronic Textiles Using Cotton Fibers with Polypyrrole and Carbon Nanotubes. Ravi M. A. P. Lima, Jose Jarib Alcaraz-Espinoza , Fernando A. G. da Silva, Jr., and Helinando P. de Oliveira. ACS Appl. Mater. Interfaces, 2018, 10 (16), pp 13783–13795. DOI: 10.1021/acsami.8b04695]