PhD awarded to Melissa Sikosana

On April 27th, 2022, during a partly on-line session, Melissa Sikosana successfully defended her PhD thesis, titled: ‘Antimicrobial coatings to maintain drinking water at point-of-use’ and was awarded the degree of Doctor.

Melissa carried out her work at the Leibniz-Institut für Polymerforschung Dresden e.V, under the supervision of Prof. Dr. Carsten Werner and Dr. Lars Renner. The now Dr. Sikosana was an Early Stage Researcher (ESR) of the Laser4FUN project. The public defense ceremony took place partly on-line at TU Dresden (Germany) and the audience could ‘attend’ the event through a video stream.

We congratulate Melissa for this achievement!

Summary of PhD thesis

Water is life. Yet, nearly a third of the global population is water insecure; with children under the age of five in low-income countries experiencing the brunt of this burden. Disinfection and safe water storage practices are vital to protect people against waterborne diseases. That said, the aim of this PhD study was to critically assess the potential of dual action antimicrobial coatings in advancing sustainable point-of-use water treatment. In this work, easy-to-apply antiadhesive and bactericidal surface coatings were developed to prevent initial bacterial adhesion and the subsequent formation of biofilms on polymeric surfaces. These coatings are based on a patented system of water-soluble, amphiphilic block copolymers of PEGylated styrene: maleic acid for in-situ biofunctionalization. On water relevant polymers surfaces (PE and PET), the coatings achieved up to 98 % and 10-fold reduction in cell viability and adhesion, respectively.

The work went a step further – it is acknowledged that a single antimicrobial approach is unlikely provide long-lasting protection against microbes in the environment. In fact, nature often uses a combination of physical and chemical components for superior surface protection (e.g. Collembola). In this direction, this work also explored the potential for a synergistic antiadhesive effects against bacteria cells to micrometric scale laser-textured features (by DLIP) on polymeric surfaces (PET), decorated with the antiseptic polymer-coating. This study revealed that this integrated approach can achieve an additive antiadhesive effect at specific feature periodicities. Looking forward, this work has significant implications on future studies aimed to better understand the complex physico-chemical interplay of bacteria-surface interactions.