Surface Functionalization with Phosphazene Substrates. Part II. Theoretical and Experimental Investigations of the Interactions of Hexachlorocyclophosphazene with Hydroxylated Silicon-based Surfaces

The interaction of hexachlorocyclophosphazene (HCCP) with the hydroxylated silicon-based surfaces is studied by a combination of XPS experimental analysis and theoretical ab initio simulations, including the estimate of the energy barriers via CI-NEB method to determine the minimum energy reaction paths. Several possible, stable chemisorbed configurations are found to exist, whose structural, energetic, and electronic properties have been analyzed in detail. The theoretical results are in good qualitative agreement with available experimental data. In particular, we get indications that water plays a crucial role in the surface functionalization with HCCP, although the presence of a suitable solvent (e.g. tetrahydrofuran, THF) seems to be essential. This paper is dedicated to Prof. Harry R. Allcock and the pioneering discoveries of his research group particularly in polyphospazenes and generally in materials science.     

Evaluation of protective and restoring effects of a mixture of silanols on photoaging. Use of a device allowing the quantification of contractile strengths of human fibroblasts after UVA irradiation

Chronic sun exposure and especially UVA wavelengths are responsible for long-term clinical skin changes such as photoageing and photocancers. The objectives of the present study were to analyse the contractile activity of fibroblasts irradiated with several doses of UVA and to evaluate the preventive, protective and restoring effects of a mixture of monomethylsilanetriol mannuronate and dimethylsilanediol salicylate. The forces generated by fibroblasts in tense collagen lattices were quantified using Glasbox device before and after UVA irradiation and the addition of a mixture of monomethylsilanetriol mannuronate and dimethylsilanediol salicylate. The production of collagen was also evaluated before and after irradiation and with and without the presence of a mixture of monomethylsilanetriol mannuronate and dimethylsilanediol salicylate. A dose of 3 J cm(-2) of UVA showed more than 50% of mortality in fibroblast population after 48 h and significant decreases in contractile forces developed by irradiated fibroblasts and collagen I production. One percentage of a mixture of monomethylsilanetriol mannuronate and dimethylsilanediol salicylate protected fibroblasts from UVA irradiation and made it possible to restore their capacity to the same level as fibroblasts that were not irradiated. It also tended to restore the capacity to synthesize collagen I. These results show that the use of the new device Glasbox makes it possible to evaluate a possible preventive and repairing effect of a cosmetic functional active on photoageing.