Subµ- to nano-scaled strategies to control initial bacterial colonization in the oral cavity and ex vivo – efficacies and modes of action

• Applicants: Professor Dr. Gianaurelio Cuniberti; Professor Dr. Christian Hannig; Professor Dr. Matthias Hannig; Dr. Ralf Helbig
• Subject Area: Dentistry, Oral Surgery ; Biomaterials ; Solid State and Surface Chemistry, Material Synthesis
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 533771434

Bacterial surface colonization can have severe consequences in the clinical environment or in food and fresh water management, leading to health and financial issues. For example, biofilm formation on non-shedding surfaces remains a key challenge in dental research, and germ spreading is a serious problem in hospitals. Depending on the specific application area, different strategies are needed to counteract bacterial adhesion. Each strategy must be adapted to the varying conditions, such as the types and presence of biomolecules, ionic strength, and bacterial species in different metabolic states. Dealing with the challenging conditions of the oral cavity, a promising approach was found in a previous DFG project. Thereby, smooth chemical textures showed that bacterial colonization could be inhibited in situ, which was not achieved with various structured surfaces. The mode of action is still unclear, but there are some indications of a decrease in the natural cohesion of the pellicle layer, which in turn reduces bacterial adhesion. This shall be clarified in the project and might lead to an optimization of the effect serving as a template for transfer into dental applications. In addition, synergistic effects of surface charges and structures are planned to be implemented for ex vivo approaches either to inhibit bacterial colonization by low adhesion forces or to counteract germ spreading by contact-induced cell lysis. There exist many preliminary studies showing that charge-associated colloid physical approaches describe, at least qualitatively, bacterial adhesion processes. Therefore, repulsive and attractive electrostatic interactions influence the initial contact differently. Since structures below the bacterial cell size, i.e. between 50 and 500 nm, have also been shown to influence initial colonization, it is obvious to combine structural and charge effects to obtain enhanced surface properties. Bioadhesion tests shall be performed in situ, in the human oral cavity, but also ex vivo, in microfluidic channels, under different flow conditions, with different ionic strengths and with bacteria in different metabolic states. In addition, a wide variety of surface analytical methods will be used to understand the mode of action and, thus, provide a roadmap of possibilities and limitations of different strategies for suppressing bacterial contamination and germ spreading under different environmental conditions.

• DFG Programme: Research Grants