Supporting information FTIR data (KBr, cm -1 ) [Eu(TTA) 3 (Bpy-Si)]: 3 431 υ as (NH); 3 090 υ as (CH); 1 627 υ s (C=O); 1 578, 1 520, 1 υ(C=C, C=S); 1 357 υ as (C-F); 682 δ(C-F); 456 υ(Eu-(Bpy-Si)); 1 578 υ(C=C, C=N ring), 1 υ(Si-C); 1 089 υ(Si-O-C); 962 δ(Si-O) and 790 δ(CH ar ). [Ga(TTA) 3 (Bpy-Si)] 3 410 υas(NH); 3 090 υ as (CH); 1 654 υ s (C=O); 1 578, 1 520, 1 υ(C=C, C=S); 1 358 υ as (C-Cl); 680 δ(C-Cl); 456 υ(Gd-L). DRIFT SiO 2 -[Eu(TTA) 3 (Bpy-Si)] and SiO 2meso -[Eu(TTA) 3 (Bpy-Si)]: 2980 ν as (CH 2 ,CH 3 ); 2 ν s (CH 2 ,CH 3 ), 1 629 υ(C=O); 1414 υ(C=C, C=S); 1238-1050 υ(Si-C) , υ(Si-O),υ(Si-O-C); δ(Si-O-Si) and 796 δ(Si-O-C). SiO 2 @[Eu(TTA) 3 (Bpy-Si)]: 2 980 ν as (CH 2 ,CH 3 ); 2 878 ν s (CH 2 ,CH 3 ), 1 640 υ(C=O); 1 υ(C=C + C=S); 1 230-1 050 υ(Si-C), υ(Si-O), υ(Si-O-C); 950 δ(Si-O-Si) and 800 δ(Si-O-C).

A series of Ru(II) complexes with monosilylated-dipyridine ligand have been synthesized and fully characterized and were then covalently attached to silica nanoparticles. Two types of hybrids were obtained depending on the experimental procedure. In the first approach, metal complexes were incorporated inside the silica nanoparticles leaving a free hydroxylated silica surface for further functionalization. These silica based nanohybrids are similar to the well known nanoparticles encapsulating [Ru(bpy) 3 ] 2+ complexes preventing the release of the dye when used in aqueous or organic solutions. Size and luminescence properties vary throughout the series of metal complexes. The second approach leads to ruthenium(II) complexes covalently attached to the silica nanoparticle surface via hydrolysis and condensation of the ethoxysilyl group with silanol sites of Ludox type silica nanoparticles. This leads to the grafting of a monolayer for complexes with the monoethoxysilyl dipyridine ligand. In contrast, the complexes with triethoxysilyl ligands can lead to small amounts of oligomers, but their quantity is limited by the sterical constraints imposed by the molecular structure. The size of the hybrids depends on the starting particles. 29 Si and 13 C solid state NMR are used to characterize silica surface properties whereas TEM and SEM confirm nanosize and morphology of the hybrids. The complexes and the nanohybrids are luminescent, with variations for ruthenium(II) complexes that are covalently incorporated or grafted on the silica surface.

Luminescent silica nanoparticles are frequently employed for biotechnology applications mainly because of their easy functionalization, photo-stability, and biocompatibility. Bifunctional silica nanoparticles (BSNPs) are described here as new efficient tools for investigating complex biological systems such as biofilms. Photoluminescence is brought about by the incorporation of a silylated ruthenium(II) complex. The surface properties of the silica particles were designed by reaction with amino-organosilanes, quaternary ammonium-organosilanes, carboxylate-organosilanes and hexamethyldisilazane. BSNPs were characterized extensively by DRIFT, (13)C and (29)Si solid state NMR, XPS, and photoluminescence. Zeta potential and contact angle measurements exhibited various surface properties (hydrophilic/hydrophobic balance and electric charge) according to the functional groups. Confocal laser scanning microscopy (CLSM) measurements showed that the spatial distribution of these nanoparticles inside a biofilm of Pseudomonas aeruginosa PAO1 depends more on their hydrophilic/hydrophobic characteristics than on their size. CLSM observations using two nanosized particles (25 and 68 nm) suggest that narrow diffusion paths exist through the extracellular polymeric substances matrix.

Luminescent silica nanoparticles (LSNPs) are frequently employed for biotechnology applications mainly because of easy functionalization, photo-stability and biocompatibility. Bifunctional silica nanoparticles (BSNPs) are described here as new efficient tools for the understanding of a complex biological system such as biofilms. Photoluminescence is brought by the incorporation of a silylated ruthenium(II) complex, surface properties of the silica particles are designed by reaction with. BSNPs are fully characterized and Zeta potential and contact angle measurements exhibit various surface properties according to the functional groups. Confocal Laser Scanning Microscopy measurements show that the spatial distribution of these nanoparticles inside P AOl biofilm depends more on their hydrophilic/hydrophobic characteristics than on their size.