Chemical engineer develops process from biopolymer
The threat of bacterial contamination is constant, both in developed countries and, mainly, in developing countries or in the third world, causing various pathologies that, particularly in hospital areas, can even cause the death of immunodeficient people. Its socioeconomic damage and the increase in the number of pathogenic bacteria resistant to antibiotics require the search for new alternatives for controlling infections. Among these, antibacterial coatings have been developed using different materials and processes. This is the scope of the research by chemical engineer Juliana Miguel Vaz, developed together with the Product Engineering and Chemistry Laboratory, of the Department of Materials and Bioproducts Engineering, of the Faculty of Chemical Engineering (FEQ) at Unicamp, supervised by professor Marisa Masumi Beppu .
The initial idea was to enable the coverage of possible repositories of microbial organisms, made up of abiotic materials – which do not have biological action, so that they could receive the coverage of an antimicrobial in a stable way. The work expanded with the development of a process that allows the addition of chitosan to Teflon and textiles used in the medical field.
In effect, the surface modification of polymers used as a substrate makes it possible to improve surface properties, facilitating the development of optimized materials with biological responses adapted or adaptable to the environment in which they will be used. On the other hand, chitosan is a biopolymer with inherent antimicrobial activity, used in a wide variety of healthcare and industrial applications, which makes it particularly interesting for the development of new functionalized materials.
Coming from natural products largely discarded by the crustacean and mollusc processing industries, chitosans have varied compositions depending on the origin and extraction processes, which can influence their actions and applications. Therefore, it is necessary to characterize these biopolymers, which constituted one of the phases of the work that focused on three types of chitosan.
Teflon and textile coating
The process of covering surfaces with chitosan developed in three distinct stages. The first involved the functionalization of the substrate surface, using the plasma technique. Plasma is nothing more than an ionized gas, made up of charged particles, in this case, resulting from the passage of a gaseous mixture of nitrogen (95%) and hydrogen (5%) through a radiofrequency system. The resulting charged particles are capable of binding to the substrate - the polymer to be modified, where chemical groups capable of reacting with other molecules are formed.
Afterwards, the potentized substrate received molecules of another substance carrying functional groups capable of establishing bonds both with itself and with the chitosan to be added, a process called grafting. Three molecules with different characteristics were tested for this purpose. Chitosan was then added to the surfaces thus prepared. The use of these spacer molecules - the grafting - is necessary because the direct bond between the substrate and chitosan is incompatible, while the spacers have functional groups capable of binding them to both the substrate and chitosan.
The efficiency of the antibacterial coating with chitosan was duly tested and confirmed using bacteria Eschrichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The promising results initially obtained on Teflon (PTFE) samples encouraged the application of the methodology on a PET substrate, a polymer widely used in conventional textiles and also in the production of hospital textiles and biomaterials. Given the results achieved, Juliana considers that “the plasma-grafting developed in the study for chitosan coatings can be applied to the production of surfaces where antibacterial activity is desired.”
Scopes of the study
The researcher considers that chitosan has an antibacterial action that still needs to be better explored, although covering surfaces with it proves to be very pronounced and effective in acting on certain types of bacteria. The developed process can also be used to explore the coagulating effect of chitosan through fabrics applied to incisions. Or even in the production of drugs in which the medicine reaches the site of action in the desired concentration. “Chitosan can also serve as a platform for the production of topical antibacterial dressings capable of gradually releasing a drug. Another possibility for the application of chitosan is in the production of nanoparticles that enable the delivery of medicines through the bloodstream to the desired organ. These are possibilities that can be seen and this is one of the importance of basic research”, says the researcher.
Juliana generalizes: “Functionalized materials have applications in the areas of medicine, engineering, transport, sportwear, among others. In industry, they can be used to minimize food contamination and meet the demand for textile polymeric products that prevent the transmission of diseases and benefit the environment through the use of normally discarded waste.”
collaborations
The group coordinated by professor Marisa Beppu has accumulated vast knowledge in the technological application of biopolymers, which has made it a reference in Brazil for researchers from different countries such as France, Holland, Portugal, Argentina, Canada, the United States, among others.
This context has allowed the laboratory coordinated by the professor to establish collaborations with researchers from various countries, enabling a very rich exchange for the training of future teachers and researchers.
In Juliana's case, the collaboration took place with the Biomaterials and Bioengineering Laboratory at Laval University, in Quebec, Canada, where Professor Diego Mantovani is internationally known in the area of biomaterials aimed more specifically at surface treatment and modification studies.
The author emphasizes: “The approaches of the two groups, although different, complement each other, allowing them to mutually add knowledge and experiences. This joint participation was essential due to the complexity and scope of areas related to the study, engineering, biotechnology, nanotechnology, physical chemistry and materials science, applied to the development of a new material and the expansion of a priority research field for Brazil” .
