Carapaces and shells of crustaceans and molluscs are sources of the polymer
Microbial organisms are widespread and lurking in the most common and different materials used in the medical field, such as instruments, exam tables and even in aprons and clothes, as well as in equipment for public use such as balusters of means of transport, handrails and door handles. , on telephone devices, on computer keys and even on food packaging.
With the aim of combating them using an antimicrobial from natural products, often disposable, chemical engineer Thiago Bezerra Taketa developed research with the Product Engineering and Chemistry Laboratory, of the Department of Materials and Bioprocess Engineering, of the Faculty of Engineering Chemistry (FEQ) at Unicamp, supervised by professor Marisa Masumi Beppu.
It would be desirable for all possible repositories of microbial organisms to have an antimicrobial coating to minimize the possibility of infections. Furthermore, it is essential that this bioactive coating, that is, it acts on cells, can be used on antimicrobial surfaces that are resistant, non-toxic, biodegradable and suitable for contact with food or humans.
The work, focused on the use of antimicrobial and nanostructured coatings containing chitosan, a derivative of chitin, focused on a rich source of this polymeric product found in the carapaces and shells of crustaceans and molluscs, which make up tons of waste normally discarded by the respective industries. processing. Chitosan is the generic name for a polymer that can have properties that vary according to the source of origin, the harvest time and the extraction and purification processes.
Indeed, research results on chitosan vary greatly due to natural and treatment conditions. It turns out that, from a natural polymer with variable or even unknown properties, products with low reproducibility are created, which are unviable for market needs. To overcome the problem, which does not exist in synthetic products, the researcher established a partnership with the group headed by professor Sérgio Paulo Campana Filho, from the Institute of Chemistry at USP-São Carlos, a specialist in obtaining natural products with properly controlled and known properties and with characteristics that best meet antimicrobial needs.
Idea and applications
The idea that guided the work was, first, to maximize the use of the high availability of a natural product, largely discarded by the crustacean and mollusc processing industry, and to reduce the appeal of petroleum-derived products. And, second, using a natural polymer that is of interest to the food and biomedical areas, which require, for example, biocompatible materials, which do not cause allergies, which have good interaction with cells, which can be used in medical devices implanted in the human body and can be used in components for curative use. These are some of the advantages of natural polymers.
Chitosan has varied applications in health preservation and biomedical contexts. The work focused on its antimicrobial use, that is, the creation, from it, of a film applied to materials in order to hinder the adhesion or proliferation of bacteria. This is the case, for example, of its use in returnable plastic bags that pose the risk of cross-contamination because they are used to transport products from various segments. In this case, it is used to cover the textile substrate so that it acquires antimicrobial properties, minimizing the likelihood of food infections. An antimicrobial fabric would also be of great value to hospitals, clinics and dental offices, preventing the proliferation of bacteria. In the medical field it could also be used in implanted devices or instruments such as catheters. The use of natural products is not yet widespread in these situations due to the variation in their compositions.
“The scope of our project is to show that, using a well-characterized raw material and knowing the process of formation and performance of coating films, we can achieve socially important applications using natural products that are often discarded”, says the author.
collaborations
In addition to the collaboration with USP São Carlos, Thiago considered the partnership between his department and the Massachusetts Institute of Technology (MIT), USA, one of the largest technology centers in the world, to be fundamental, where, for a year, he had contact with the greatest experts in the area, such as professors Michael Rubner and Robert Cohen, in addition to access to sophisticated equipment, factors that contributed to his improvement in the technique used.
Thiago spent a year at MIT carrying out the morphological and chemical characterization of antimicrobial films obtained on silicon sheets immersed, alternately, in a solution of chitosan, which has a positive charge, and a cellulose derivative, with a negative charge – method of dip, and determining its antimicrobial potential and mechanisms of action. Knowing the chemical composition of the film and the interaction of molecules in antimicrobial activity, he reached unprecedented results in relation to what was known about the performance of chitosan, which, despite being widely used, lacked fundamental information about the film formation process and its interaction with other molecules.
He emphasizes the importance of partnerships established in interdisciplinary work that involves chemistry, engineering and microbiology and in which advanced knowledge in different areas must be relied upon: “Without these collaborations, the scope of our research would be smaller.”
