Professor Elson Longo (CDMF-UFSCar), founding member and former president of B-MRS, is the corresponding author of an article that appears in the Top 100 2018 ranking of the journal Scientific Reports in the area of Materials Science. The ranking highlights the most read articles in 2018, among those published that year in the journal of the Nature group. The paper was published on January 30, 2018 and received 1,042 views throughout the year.
Entitled Towards the scale-up of the formation of nanoparticles on alpha-Ag2WO4 with bactericidal properties by femtosecond laser irradiation, the article is signed by eleven authors, six of them from Brazilian institutions, including the researcher Camila Cristina de Foggi (UNESP), who is also a B-MRS member.
The work proposes a new process to produce bactericidal nanocomposites based on silver nanoparticles and semiconductor materials. The method increases 32 times the bactericidal action of the nanocomposite and, at the same time, generates a new class of spherical nanoparticles.
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
“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.
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.
[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]
In the research group of Professor Kirk Schanze, conjugated polyelectrolytes (CPEs) have been the subject of both fundamental studies and applications. The group has already explore CPEs as fluorescent sensors, in solar cells and as biocidal materials.
On September 13, in Gramado, Kirk Schanze, who is a Professor at the University of Texas at San Antonio (UTSA) and editor-in-chief of ACS Applied Materials & Interfaces, will take some time out of his busy schedule to deliver a plenary lecture on CPEs in the XVI B-MRS Meeting.
Schanze graduated in Chemistry from Florida State University in 1979. Four years later, he earned his Ph.D., also in Chemistry, from the University of North Carolina at Chapel Hill. Soon after, he was appointed a Miller Postdoctoral Fellow at the University of California, Berkeley. In 1986, he joined the University of Florida (UF) as a professor of the Department of Chemistry. There, he chaired the Division of Organic Chemistry, held the Prominski Chair of Chemistry, and founded the Schanze Group, which today continues its research activities at UTSA. In 2016, Schanze left UF to hold the Robert A. Welch Distinguished University Chair in Chemistry at UTSA.
Between 2000 and 2008, Schanze served as senior editor of the prestigious journal Langmuir. Shortly thereafter, he became the first editor-in-chief of ACS Applied Materials & Interfaces, which had just been released.
Prof. Schanze has authored about 300 papers and 20 patents. According to Google Scholar, his scientific production has more than 16,000 citations and his h index is 71. He is fellow of the American Chemical Society (ACS). He was a visiting professor at the Harbin Institute of Technology (China) and the Tokyo Metropolitan University (Japan) in 2011, at the Ecole Normale Supérieure Cachan (France) in 2008 and at the Chemical Research Promotion Center (Taiwan) in 2007. He has received distinctions from the American Chemical Society, National Science Foundation, University of Florida, Japan Society for Promotion of Science, and Japanese Photochemical Association, among other entities.
Here follows an interview with the scientist.
B-MRS newsletter: – In your opinion, what are your main scientific and/ or technological contributions to the field of conjugated polyelectrolytes? Describe them briefly and feel free to share a few references of your papers, patents or books.
Kirk Schanze: – We were among the first groups to study conjugated polyelectrolytes, which are water soluble conjugated polymers. Following are some of the key contributions from our group to this field:
a) Our lab was the first to report the synthesis of a water soluble, fluorescent poly(phenylene ethynylene) sulfonate (PPE-SO3) and describe the application to fluorescence sensing of ions in water at ultralow concentration.
b) We were the first to report the use of a fluorescent conjugated polyelectrolyte as a sensor for enzyme activity, which is an important biosensing application.
c) Our lab has developed the applications of cationic conjugated polyelectrolytes to sensing phosphatase enzyme activity. These enzymes are important in a number of biologically significant processes. [3,4]
d) Working in collaboration with Prof. David Whitten of the University of New Mexico, we have developed cationic conjugated polyelectrolytes as a novel class of antibacterial agents.[5,6]
 C. Tan, M. R. Pinto and K. S. Schanze, “Photophysics, Aggregation and Amplified Quenching of a Water-Soluble poly(Phenylene ethynylene)”, Chem. Commun.2002, 446-447, 10.1039/B109630C.
 M. R. Pinto and K. S. Schanze, “Amplified Fluorescence Sensing of Protease Activity with Conjugated Polyelectrolytes”, Proc. Nat. Acad. Sci. USA, 2004, 101, 7505, 10.1073/pnas.0402280101.
 Zhao, X.; Liu, Y.; Schanze, K. S., “A Conjugated Polyelectrolyte Based Fluorescence Sensor for Pyrophosphate”, Chem. Commun. 2007, 2914-2916, 10.1039/b706629e.
 Zhao, X. Y.; Schanze, K. S., “Fluorescent Ratiometric Sensing of Pyrophosphate via Induced Aggregation of a Conjugated Polyelectrolyte”, Chem. Commun. 2010, 46, 6075-6077, 10.1039/c0cc01332c.
 Ji, E.; Corbitt, T. S.; Parthasarathy, A.; Schanze, K. S.; Whitten, D. G., “Light and Dark-Activated Biocidal Activity of Conjugated Polyelectrolytes”, ACS Appl. Mater. Interfaces 2011, 3, 2820-2829, 10.1021/am200644g.
 299. Huang, Y.; Pappas, H. C.; Zhang, L.; Wang, S.; Cai, R.; Tan, W.; Wang, S.; Whitten, D. G.; Schanze, K. S., “Selective Imaging and Inactivation of Bacteria over Mammalian Cells by Imidazolium Substituted Polythiophene”, Chem. Mater. 2017, 2017, 29, 6389–6395, 10.1021/acs.chemmater.7b01796.
B-MRS Newsletter: – You have been the Editor-in-Chief of ACS Applied Materials & Interfaces since its release, haven´t you? In less than 10 years, the journal hit an impact factor of 7,504. To what factors do you attribute this good result?
Kirk Schanze: – ACS Applied Materials & Interfaces (AMI) publishes papers that come from a currently very active area of materials research, specifically applied materials/interfaces. There is a large community of scientists and engineers around the globe who are working in this field. AMI has a global community of editors and editorial board members who represent their regions. Indeed, the newest editor who has joined our editorial board is Prof. Osvaldo Oliveira Jr. of the University of Sao Paulo!
B-MRS Newsletter: – We often see papers from the Brazilian Materials Community at ACS Applied Materials & Interfaces. Could you share with our readers some numbers about the participation of Brazilian authors in the journal?
Kirk Schanze: – ACS Applied Materials & Interfaces has published more than 100 papers with authors or co-authors from Brazil. Many of these papers have been highly cited in the field of materials science. Examples of highly cited papers are:
K. Poznyak†, J. Tedim†, L. M. Rodrigues†‡, A. N. Salak†, M. L. Zheludkevich*†, L. F. P. Dick‡ and M. G. S. Ferreira†§ Novel Inorganic Host Layered Double Hydroxides Intercalated with Guest Organic Inhibitors for Anticorrosion Applications, ACS Appl. Mater. Interfaces, 2009, 1 (10), pp 2353–2362, DOI: 10.1021/am900495r (co-author from Rio Grande do Sul Federal University in Porto Alegre)
Heberton Wender*†, Adriano F. Feil†, Leonardo B. Diaz†, Camila S. Ribeiro‡, Guilherme J. Machado†, Pedro Migowski§, Daniel E. Weibel‡, Jairton Dupont§, and Sérgio R. Teixeira*† Self-Organized TiO2 Nanotube Arrays: Synthesis by Anodization in an Ionic Liquid and Assessment of Photocatalytic Properties, ACS Appl. Mater. Interfaces, 2011, 3 (4), pp 1359–1365, DOI: 10.1021/am200156d
B-MRS Newsletter: – Please, leave an invitation to your plenary talk.
Kirk Schanze: – Everyone is invited to attend my talk which will highlight our work of conjugated polyelectrolyte as applied in the field of energy- and bio- materials chemistry.