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PhD Defence Daniele Di Iorio

designer surfaces for the quantification of multivalent biological interactions

Daniele Di Iorio is a PhD in the research group Molecular Nanofabrication (MnF). His supervisor is J. Huskens from the faculty of Science and Technology.

Influenza represents a serious global health issue that causes millions of infections every year. Quantification of the multivalent interaction of the influenza virus binding at a host cell surface can lead to a better understanding of its multivalent binding energy landscape and provide ways to tackle biological questions regarding influenza virulence and zoonoses. For this reason, the development of platforms and devices that allow the quantification of these interactions is required. Specifically, when designing such platforms, various prerequisites, such as good antifouling properties, control over the surface ligand density and capability of mimicking cell membranes, need to be met.

The research discussed in this thesis is aimed at developing surface chemistry methods that allow the selective modification of surfaces with biomolecules for the study of multivalent biological interactions, such as that of the influenza virus with cell surface receptors. Two different approaches were examined in this dissertation. In the first part of the thesis, the use of functionalized poly-l-lysine (PLL) for the formation of polyelectrolyte monolayers has been discussed. With this method, the selective functionalization of several types of surfaces was achieved, and its efficacy in detecting DNA has been explored. The second part has focused on the formation of cell membrane mimics, based on supported lipid bilayers (SLBs), for the quantification of flu virus interactions.

Results obtained with PLL polymers showed the power of functionalizing a wide range of substrates for the controlled modification of surfaces with biomolecules while retaining their biological activity. At the same time, the SLB platform developed here provided access to the quantification of multivalent binding of the flu virus at artificial cell surface mimics with a precise control of the surface ligand/receptor density.

We expect that the surface functionalization methods developed here can be used for the further development of biosensors, allowing quantification of multivalent interactions and the discrimination of different types of flu virus strains. These techniques can be employed for the investigation of a wider range of biological, monovalent and multivalent interactions at interfaces, thus providing insight into complex biomolecular mechanisms.