HCl was purchased from Romil (Cambridge, UK). Absolute selleck compound ethanol and H2O2 was purchased from Carlo Erba (Milan, PD173074 Italy); HEPES powder was purchased from Promega (Madison, WI, USA). Purification of diatomite powder Five grams of crashed diatomite rocks were resuspended into 250 ml of absolute ethanol and sonicated for 5 h to break large aggregates. The dispersion was sieved through a nylon net filter with pore size of 41 μm, and then filtered with pore size of 0.45 μm (Millipore, Billerica, MA, USA). The diatomite nanopowder was purified to remove organic and inorganic impurities

[9, 10]. The sample was centrifuged and the pellet treated with Piranha solution (2 M H2SO4, 10% H2O2) for 30 min at 80°C. Nanoparticle dispersion was centrifuged for 30 min at 21,500 × g, washed twice with distilled water, resuspended in 5 M HCl, and incubated over night at 80°C. DNPs were then centrifuged for 30 min at 21,500 × g and washed twice with distilled water to eliminate HCl residues. Characterization of nanoparticles size The size and zeta-potential measurements of purified Selleck Talazoparib diatomite nanoparticles dispersed in water (pH = 7) were performed before and after

APTES functionalization by dynamic light scattering (DLS) using a Zetasizer Nano ZS (Malvern Instruments, Malvern, UK) equipped with a He-Ne laser (633 nm, fixed scattering angle of 173°, 25°C). Transmission electron Bcl-w microscopy (TEM) and scanning electron microscopy (SEM) were also used

to investigate nanoparticles morphology. Briefly, in TEM analysis, purified diatomite nanoshells were characterized by placing a drop of suspension on a TEM copper grid with a lacy carbon film and then observed by a Jeol 1011 TEM (Peabody, MA, USA) at an accelerating voltage of 100 KV. For SEM characterization, diatomite samples were deposited on crystalline silicon substrates mounted on a double-faced conductive adhesive tape. Images were acquired at 5-kV accelerating voltage and 30-μm wide aperture. Cell culture The human lung epidermoid cancer cell line (H1355), obtained from American Type Tissue Collection (Rockville, MD, USA), was grown at 37°C with an atmosphere of 5% CO2, in RPMI 1640 (GIBCO) medium supplemented with 10% heat inactivated FBS (GIBCO), 100 U/mL penicillin, 100 mg/mL streptomycin, 1% l-glutamine. Diatomite functionalization Purified nanoparticles were amino-modified with a 5% (v/v) APTES solution in absolute ethanol [13, 14]. The APTES film formation was carried out for 1 h at room temperature with stirring in a dark condition. After this step, the sample was centrifuged for 30 min at 21,500 × g and supernatant discarded. The functionalized diatomite were washed twice with absolute ethanol and the collected pellet was incubated for 10 min at 100°C (curing process). Finally, the sample was washed twice with absolute ethanol and twice with 20 mM HEPES buffer pH 7.5.