A multidisciplinary team of scientists, led by Jorge Coelho and Paula Morais, from the Faculty of Science and Technology of the University of Coimbra (FCTUC), developed a varnish for surfaces that kills bacteria, even the most resistant ones, in just 15 minutes, a safe solution and effective to prevent and combat hospital infections.
This new intelligent varnish with high antimicrobial activity, which is activated by the action of white light, harmless to humans, was developed within the scope of the “SafeSurf” research project, funded by the Foundation for Science and Technology (FCT), and it had the participation of researchers from the Faculty of Engineering of the University of Porto (FEUP) and the University of Trás-os-Montes and Alto Douro (UTAD).
The project, whose results are already published in the scientific journal ACS Applied Materials & Interfaces, comprised three phases. First, scientists developed and tested a new generation of cationic polymers with antimicrobial properties against various species of bacteria. Then, they looked for a photosensitizer with photodynamic activity on the surface, using a natural compound that is produced by plants, curcumin.
By combining cationic polymers with curcumin, the scientists found that the polymers’ antimicrobial activity increased significantly, allowing a greater number of bacteria to be killed in less time, as Jorge Coelho and Paula Morais report: «when we brought the two together under the action of white light, we found that the bacteria died in a very short time. The various experiments carried out on surfaces showed that, in just 15 minutes of exposure, these two compounds combined reduced a thousand times the number of gram-positive and gram-negative bacteria, such as, for example, Escherichia coli. In other words, in a joint action, the two materials cause oxidative stress in the bacteria, eliminating them effectively and safely».
In view of the results obtained, the researchers then proceeded to formulate a coating (varnish). Using an industrial formulation, they developed a polyurethane-based varnish containing, for the first time, cationic polymeric biocides combined with a curcumin photosensitizer.
The battery of antimicrobial tests carried out with the developed varnish showed effectiveness in eliminating bacteria. The great innovation, according to the project coordinators, lies in the fact that «we were able to incorporate these two compounds in a polyurethane-based industrial formulation varnish, using industrial conditions, giving the varnish the innovation of antibacterial functionality, thus facilitating its introduction into the market. The formulation of the varnish containing the cationic polymers and the photosensitizer constituted a stage of the highly complex project that was carried out by our colleagues at FEUP».