Figure 2

Characterization of ferritin produced in HEK-293T cells. TEM images and nanoparticle core size distributions from FLAG-tag immunoprecipitation. (a) TEM image of phosphotungstic acid stained ferritin nanoparticles purified from HEK-FtD cells grown in media supplemented with 10% FBS, 0 mg⋅mL⁻¹ HTF, and 500 μM FeC. (b) HRTEM image of an unstained ferritin nanoparticle collected from HEK-FtD cells grown in media supplemented with 1% FBS, 0 mg∙mL⁻¹ HTF, and 0 μM FeC. HRTEM shows a clear ED pattern of a highly crystalline lattice (inset using region circled in white) when analyzed using the ImageJ FIJI FFT function. (c) Core size distributions from unstained TEM images of ferritin nanoparticles collected from HEK-FtD cells grown under four growth medium conditions. TEM images were analyzed using the ImageJ FIJI nanoparticle size function, in which a minimum of 100 nanoparticles were measured, and distributions were normalized by their respective total nanoparticle counts. Statistical significance for differences in ferritin core size distributions shown in (c) was calculated using two-way ANOVA with Tukey’s multiple comparisons test, which found a significant two-way interaction between FBS and FeC concentration in growth media on core size, F(1,1,051) = 8.896, p = 0.0029.