Effect of chemical modification on surface free energy components of Aerosil silica powders determined with capillary rise technique

Particles' Organization in Direct Oil-in-Water and Reverse Water-in-Oil Pickering Emulsions

This paper addresses the impact of the particle initial wetting and the viscosity of the oil phase on the structure and rheological properties of direct (Oil/Water) and reverse (Water/Oil) Pickering emulsions. The emulsion structure was investigated via confocal microscopy and static light scattering. The flow and viscoelastic properties were probed by a stress-controlled rheometer. Partially hydrophobic silica particles have been employed at 1 and 4 wt.% to stabilize dodecane or paraffin-based emulsions at 20 vol.% of the dispersed phase. W/O emulsions were obtained when the particles were dispersed in the oily phase while O/W emulsions were prepared when the silica was introduced in the aqueous phase. We demonstrated that, although the particles adsorbed at the droplets interfaces for all the emulsions, their organization, the emulsion structure and their rheological properties depend in which phase they were previously dispersed in. We discuss these features as a function of the particle concentration and the oil viscosity.

Titania and silica nanoparticles coupled to Chlorin e6 for anti-cancer photodynamic therapy

In this study, light-sensitive photosensitizers (Chlorin e6, Ce6) were linked to TiO₂ and SiO₂ nanoparticles (NPs) in order to develop new kinds of NP-based drug delivery systems for cancer treatment by PDT. TiO₂ or SiO₂ NPs were modified either by the growth of a polysiloxane layer constituted of two silane reagents ((3-aminopropyl)triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS)) around the core (PEGylated NPs: TiO₂@4Si-Ce6-PEG, SiO₂@4Si-Ce6-PEG) or simply modified by APTES alone (APTES-modified NPs: TiO₂-APTES-Ce6, SiO₂-APTES-Ce6). Ce6 was covalently attached onto the modified TiO₂ and SiO₂ NPs via an amide bond. The absorption profile of the hybridized NPs was extended to the visible region of the light. The physicochemical properties of these NPs were explored by TEM, HR-TEM, XRD, FTIR and zeta potential. The photophysical characteristics including the light absorption, the fluorescence properties and the production reactive oxygen species (¹O₂ and HO) were also addressed. In vitro experiments on glioblastoma U87 cells were performed to evaluate the photodynamic efficiency of the new hybridized NPs. The cells were exposed to different concentrations of NPs and illuminated (λ_exc = 652 nm, fluence rate 10 J/cm²). In contrast to the PEGylated NPs, the APTES-modified nanosystems were found to be more efficient for PDT. An interesting photodynamic effect was observed in the case of TiO₂-APTES-Ce6 NPs. After illumination, the viability of U87 was decreased by 89% when they were exposed to 200 μg/mL of TiO₂-APTES-Ce6 NPs, which corresponds to 0.22 μM of Ce6. The same effect can be obtained with free photosensitizer but using a higher concentration of 10 μM of Ce6.

Fabrication and evaluation of polymeric membranes for blood dialysis treatments using functionalized MWCNT based nanocomposite and sulphonated-PES

The use of polyethersulfone based membranes for dialysis therapy is increasing, but the poor bio-compatibility of the PES membrane can raise severe blood reactions affecting the rate of morbidity and mortality of hemodialysis (HD) patients.