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Differences in ubiquitin binding modes to nanocavities in SBA15, MCM41 silica and entrapped in host silica material using 2D ¹³C DARR and 1D ¹H-¹³C INEPT MAS NMR spectroscopy

Immobilizing proteins on surfaces has important roles in many applications especially in the development of biomedical devices and biosensors, but also enables us to learn on biological regulation of biomaterial formation. In this work, designed to benchmark the effect of surface properties, we chose silica since it is known to be biocompatible and easily modifiable material.. From the protein side we chose ubiquitin as the model since it is a small and stable protein, involved in many cell processes like exocytosis, DNA repair and degradation of waste proteins. In this work, ubiquitin was adsorbed on MCM41 /SBA15 and was entrapped in silica. The questions that we would like to answer relate to the regions in the protein that are exposed to interaction with the silica, whether differences in the surface chemistry of different silica influences that interfaces with the protein and more generally to develop atomically detailed insights into bio-material interfaces. To answer this question we coupled 1D ¹H-¹³C INEPT to examine dynamic regions of the adsorbed/ entrapped ubiquitin with 2D ¹³C DARR experiments to examine the regions that interact with the different type silica and structural changes taking place in the different silica environments. In particular we investigated effects of hydrophobic vs. hydrophilic character of the silica on the structure of the protein.