Spherical Ag, Au, Pt, Al2O3, SiO2 and ZnO NPs of approximate 10 nm size were purchased from Meliorum nanotechnologies (Rochester, NY, USA). CdSe/ZnS quantum dot (LumiDot™) dispersed in toluene (QD1) was purchased from Sigma Aldrich (St. Louis, MO, USA). Water-soluble core/shell CdSe/ZnS (QD2) and core only CdSe (QD3) particles with mercaptoundecanoic acid (MUA) surface modification were purchased from NN laboratories (Fayetteville, AR, USA) (see Table S1 and Table 2 for details). Working solutions of these NPs were prepared in Bronchial Epithelial Growth Medium (BEGM) (Lonza, San Diego, CA) and complete Dulbecco's Modified Eagle's Medium (CDMEM) (Invitrogen, Carlsbad, USA). Dry powder NPs (Ag, Au, Pt, Al2O3, SiO2 and ZnO) were weighed and added to deionized water at a concentration of 5 mg/mL to make up the stock solutions. These solutions were subjected to water bath ultrasonication (3 W) and aliquoted to prepare working solutions. 20 μL of 4% bovine serum albumin (BSA) (Fraction –V; Gemini Bio-products, USA) was added to an equal volume of each of the stock suspensions and allowed to equilibrate for 30 min at room temperature. 1 mL CDMEM (complete DMEM containing 10% FBS) or 1 mL BEGM (supplemented with 2 mg/mL BSA) was added to the BSA-stabilized NP suspensions before sonication for 15 sec using a probe-sonicator (VibraCell™, Sonics, CT, USA) at 30 W.17 The scheme for preparing a NP suspension in tissue culture medium is shown in Figure S2 and assessment of suspension stability is displayed in Figure S3 .
For zebrafish experiments, we used Holtfreter's medium which contains 3.5 g NaCl, 0.20 g NaCO3, 0.05 g KCl, 0.12 g CaCl2 dihydrate in 1000 mL of de-ionized water, pH 6.5–7. The filtered solution was supplemented with alginic acid (Sigma Aldrich) at a concentration of 100 ppm. Alginate was chosen as an environmentally relevant stabilizing agent. Aliquoted NP stock solutions were added to the Holtfreter's medium supplemented with alginate at a range of concentrations (6.25, 12.5, 25 and 50 μg/mL) and sonicated for 15 sec using a probe sonicator. The scheme for preparing the NPs in Holtfreter's medium is shown inFigure S2 and the suspension stability is displayed in Figure S6 .
For zebrafish experiments, we used Holtfreter's medium which contains 3.5 g NaCl, 0.20 g NaCO3, 0.05 g KCl, 0.12 g CaCl2 dihydrate in 1000 mL of de-ionized water, pH 6.5–7. The filtered solution was supplemented with alginic acid (Sigma Aldrich) at a concentration of 100 ppm. Alginate was chosen as an environmentally relevant stabilizing agent. Aliquoted NP stock solutions were added to the Holtfreter's medium supplemented with alginate at a range of concentrations (6.25, 12.5, 25 and 50 μg/mL) and sonicated for 15 sec using a probe sonicator. The scheme for preparing the NPs in Holtfreter's medium is shown in
