The infrared spectra of water confined in well controlled pore glasses were recorded as a function of the pore size ranging from 8 to 320 nm and in the 30–4000 cm⁻¹ spectral range using the ATR technique. The experiments prove that even in the large pores, the water network is significantly perturbed. The energy of the connectivity (or hindered translation) band (around 150 cm⁻¹) is found to increase when the pore size decreases, indicating that confinement increases the H-bonding between neighbouring water molecules. Moreover, a drastic decrease of the FWHM of the connectivity band was observed upon confinement. This can be related to some ordering induced by the rigid walls of the pores. Furthermore, the partial filling of pores causes a significant modification to the water network, resembling heating of the trapped liquid and suggesting a role played by the water/air interface.

The understanding of the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest in both fundamental research and applications such as nanotechnology. However, despite intense research, the mechanisms and the structural determinants of protein/surface interactions are still unclear. We developed a strategy consisting in identifying, in a mixture of hundreds of soluble proteins, those proteins that are adsorbed on the surface and those that are not. If the two protein subsets are large enough, their statistical comparative analysis must reveal the physicochemical determinants relevant for adsorption versus non-adsorption. This methodology was tested with silica nanoparticles. We found that the adsorbed proteins contain a higher number of charged amino acids, particularly arginine, which is consistent with involvement of this basic amino acid in electrostatic interactions with silica. The analysis also identified a marked bias toward low aromatic amino acid content (phenylalanine, tryptophan, tyrosine and histidine) in adsorbed proteins. Structural analyses and molecular dynamics simulations of proteins from the two groups indicate that non-adsorbed proteins have twice as many π-π interactions and higher structural rigidity. The data are consistent with the notion that adsorption is correlated with the flexibility of the protein and with its ability to spread on the surface. Our findings led us to propose a refined model of protein adsorption.