Preparation of cytocompatibleluminescent and magnetic nanohybrids based on ZnO, Zn0.95Ni0.05O and core@shell ZnO@Fe2O3 polymer grafted nanoparticles for biomedical imaging

I. Balti, A. Barrère, V. Gueguen, L. Poussard, G. Pavon-Djavid, A. Meddahi-Pellé,

P. Rabu, L. Samia Smiri, N. Jouini, F. Chaubet

Supplementary materials

EXPERIMENTAL

Materials. Zinc acetate, iron acetate, nickel acetate, diethylene glycol, 1,2-propanediol, sodium hydroxyde, α-bromoisobutyric acid, oleic acid, hexane, copper bromide, 2,2’-dipyridyl, sodium styrene sulfonate, sodium methracrylate and L-glutamine were purchased from Aldrich. Phosphate buffer saline, Dulbecco’s Modified Eagle Medium and fetal bovine serum were obtained from Life Technologies (StAubin, France). Penicillin, triton X-100 and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide were purchased from Sigma. Red phalloidin FluoProbes B-607 was purchased from Interchim (Montluçon, France). Acetone and ethanol were obtained from Carlo Erba. Acetylacetone, isopropanol and formaldehyde were purchased from Fluka. Ultrapure milli-Q-water (18.3 MΏ.cm) was used as a solvent.

2-2 Synthesis conditions of nanoparticles cores. The synthesis conditions of ZnO and Ni-substituted ZnO NPs are described in detail elsewhere (Balti et al. 2011; Dakhlaoui et al. 2009). Briefly, ZnO and Zn0.95Ni0.05ONPs were prepared using forced hydrolysis of acetate metallic salts in a polyol medium:diethylene glycol (DEG) and 1,2-propanediol, respectively. An appropriate amount of metallic salts was dissolved in 50 ml of polyol (DEG or 1,2-propanediol) and then heated at the desired temperature for 4 h under continuous mechanical stirring. At the end of the reaction, the precipitate was centrifuged, washed several times with ethanol and acetone, and then dried under vacuum at 50 °C. The chemical analysis of nickel element in Zn0.95Ni0.05O NPswas conducted at the CNRS central analysis service (Vernaison, France). Core-shellZnO@γ-Fe2O3 was prepared according to the following process: appropriate amounts of zinc acetate dihydrate (2mmol), sodium hydroxide (8mmol)and 5 mL of ultrapure water were successively introduced in 50mL of DEG, sonicated for 30 min and then heated to reflux (245 °C) for 4h. After cooling to room temperature, a white homogeneous suspension was obtained. Then a solution of iron acetate (2mmol) in DEG (10 mL) was injected into the suspension obtained above, and the mixture was slowly heated to 245 °C for another 4h. The precipitate was separated from the supernatant by centrifugation (8,000 rpm for 15 min), washed several times with ethanol and acetone before drying under vacuum at 50 °C.

2-3 Modification of nanoparticles with α-bromoisobutyric acid. The as-prepared NPs were modified with oleic acid toprepareastablecolloidalsuspension (Sun et al. 2007; Puntes et al. 2002) : 1 g of particles was dispersed into 15 mL of DEG, then a solution of 10 mL of oleic acid in 90 mL of hexane was added. The mixture was sonicated for 1 h and kept at room temperature for three days. The hexane phase was collected and 2 g of α-bromoisobutyric acid were added. The suspension was mechanically stirred for 24 h under N2 bubbling at room temperature. The modified particles were separated by centrifugation (8,000 rpm for 15 min) and washed several times with ethanol before drying under vacuum at 50 °C.

2-4 ATRP of poly (sodium4-styrenesulfonate) (PSS) and poly (sodium-4-styrenesulfonate – co – sodium methacrylate) P(SS-co-MA). The activated NPs (1.0 g), CuBr (1.2 mmol), 2,2’-dipyridyl (2.4 mmol), sodium styrene sulfonate (SS) monomer (24 mmol) and 50 mL of ultrapure water were mixed into a 100 mL round-bottom flask under a nitrogen atmosphere, sonicated for 30 min and heated at 60 °C for 2 h under N2 bubbling. The precipitate was then collected by centrifugation at 8,000 rpm for 15 min and washed several times with ultrapure water and ethanol to remove the ungrafted monomer. The resulting suspension was extracted with acetylacetone-ethanol solution (100 mL, vol. ratio 1:5) for 24 h (Liu et al. 2006) to remove the copper contaminants and dried under vacuum for 24 h. The ATRP of P(SS-co-MA) from the modified ZnO was accomplished by the same procedure with an equimolar mixture of sodium 4-styrenesulfonate and sodium methacrylate.

Methods

Transmission electron microscopy (TEM) observations were carried out with a Jeol 2011 microscope (Jeol, Croissy-sur-Seine, France) operating at 100 kV. The sample powder was dispersed in ethanol, one drop of the suspension was deposited on the carbon membrane of the microscope grid and the solvent was evaporated at room temperature.

The IR data were collected in the 4,000–600 cm-1 range with a Perkin-Elmer FT-IR Spectrum BX spectrophotometer (PerkinElmer, Courtaboeuf,France) using the KBr pellet technique.

Supporting figure 1:Size distributions of A. Zn0.95Ni0.05O, B. PSS-g-Zn0.95Ni0.05O, C. ZnO@Fe2O3 and D. PSS-g-ZnO@Fe2O3, as deduced from the analysis of TEM images. The fit of the distribution by a Lorentzian is also reported (black line).

Supporting figure 2: FT-IR spectra of bare and coated Zn0.95Ni0.05O