Fig. 1

Nanocomposite and nanoconjugate Cryo-TEM show different degrees of aggregation resulting in corresponding differences in nanocomposite uptake by neuroblastoma cells. a Cryo-TEM images of bare Fe₃O₄@TiO₂ nanocomposites; b DOPAC–Fe₃O₄@TiO₂ nanoconjugates, and c MIBG–DOPAC–Fe₃O₄@TiO₂ nanoconjugates mixed with complete cell media, plunge-frozen on lacy carbon grids and imaged under cryogenic conditions at 120 kV. For EDS–STEM and IR spectroscopy of nanocomposites, see supplemental Figs. 1 and 2. d SK-N-AS cells were treated with 250 nM bare Fe₃O₄@TiO₂ nanocomposites, DOPAC–Fe₃O₄@TiO₂ nanoconjugates or MIBG–DOPAC–Fe₃O₄@TiO₂ nanoconjugates for 1 h (n = 3), washed and collected after trypsinization. Bar graph shows relative quantity of Ti per 10⁵ cells; e same work was done with SK-N-DZ cells. The total concentration of Ti (ppb) per sample was evaluated by ICP-MS and adjusted for the number of cells counted prior to sample processing for ICP-MS. The final concentration of Ti per 10⁵ cells is expressed as a percentage of bare Fe₃O₄@TiO₂ nanocomposite uptake; control value corresponds to Ti background from cells not treated with nanoconstructs. Data presented are an average of at least two independent experiments, each with three biological replicates. Error bars indicate mean ± SD. *** < 0.001 significance level