PhD Discussion Sessions: Berta Gumí and Natalia Feiner

Nanomechanical and structural properties of supported lipid bilayers

Biological membranes are flexible self-sealing boundaries that form the permeability barriers for cells and organelles, also playing a structural role under combination of forces. Understanding the physical properties of the membrane is essential to get a better knowledge on the function of its constituents. Moreover, changes in membrane properties can affect receptor functioning, protein-membrane and protein-protein associations, as well as small molecule gradients. With atomic force microscopy (AFM) and AFM-based force spectroscopy (AFM-FS) we evaluate morphological and nanomechanical parameters of hydrated supported lipid bilayers (SLBs), that can be directly correlated with the lipid lateral organization and composition in the membrane. Being SLBs 2D ordered structures, grazing incidence X-Rays (XR) techniques are powerful to probe lateral and vertical organization in the length scales ranging from angstroms to microns. By combining AFM and XR we obtain not only information about the morphological and nanomechanical properties, but also more insights on the structure and organization of SLBs. This approach allows studying the interaction of membrane constituents and its associations with small molecules.

Studying nanoparticle interactions with blood components using super resolution microscopy

The formation of the protein corona when nanoparticles are introduced into the blood stream alters their interactions with the target cells, affecting their functionality and performances in vivo [1]. Therefore, to improve the design of effective nanoparticles it is important to understand the composition and temporal evolution of the protein corona. In the present work we use super-resolution optical microscopy (SRM) to study the protein corona growing on mesoporous silica nanoparticles. SRM enables us not only the imaging but the quantification of single proteins [ref]. Interestingly, we observed a significant heterogeneity in protein absorption between individual nanoparticles which was only possible to detect thanks to the high resolution of the technique and its ability to image in a particle-by-particle basis. We studied the role of the surface chemistry in the corona formation and the role of the degradability in the corona evolution in time. Moreover, we investigate the consequences of protein corona formation on selective cell targeting which provide us a detailed understanding of corona-activity relations. The present methodology is widely applicable to a variety of nanostructures and complements the existing ensemble approaches to further investigate protein corona phenomenon.

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