In this paper, we demonstrate that in addition to the nature of the ions the nature of the surface is also of vital importance in order to elucidate the origin of Hofmeister effects. Specifically, we show that for the solid/ water interface when the surface turns from hydrophobic to hydrophilic, an inversion in the Hofmeister series occurs. Results were recorded from colloidal-stability experiments performed with seven different anions located at different positions in the Hofmeister series and working with four colloidal systems that varied in their surface-charge sign and hydrophobic/philic degree. A mechanism based on the structural modifications that ions and surfaces induced in water is proposed to explain all these results. The existence of hydration forces on hydrophilic systems enables us to explain the data and to reinforce our arguments concerning the relevance of considering the water structure around both the ions and the interfaces on Hofmeister effects.

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Lipid nanocapsules (NCs) represent promising tools in clinical practice for diagnosis and therapy applications. However, the NC appropriate functionalization is essential to guarantee high biocompatibility and molecule loading ability. In any medical application, the immune system-impact of differently functionalized NCs still remains to be fully understood. A comprehensive study on the action exerted on human peripheral blood mononuclear cells (PBMCs) and major immune subpopulations by three different NC coatings: pluronic, chitosan and polyethylene glycol-polylactic acid (PEG) is reported. After a deep particle characterization, the uptake was assessed by flow-cytometry and confocal microscopy, focusing then on apoptosis, necrosis and proliferation impact in T cells and monocytes. Cell functionality by cell diameter variations, different activation marker analysis and cytokine assays were performed. We demonstrated that the NCs impact on the immune cell response is strongly correlated to their coating. Pluronic-NCs were able to induce immunomodulation of innate immunity inducing monocyte activations. Immunomodulation was observed in monocytes and T lymphocytes treated with Chitosan-NCs. Conversely, PEG-NCs were completely inert. These findings are of particular value towards a pre-selection of specific NC coatings depending on biomedical purposes for pre-clinical investigations; i.e. the immune-specific action of particular NC coating can be excellent for immunotherapy applications.