Fig. 3. Evaluation of the BNNT/β-glucan-IgG complex as a tumor-selective boron agent for BNCT. (a) Intracellular uptake of BNNT into SK-OV-3 cells in the presence (blue) and absence (red) of IgG. The cells were exposed to the samples ([B] = 1, 10 ppm) for 24 h. (b) Intracellular uptake mechanism of the BNNT/β-glucan-IgG complex. SK-OV-3 cells were preincubated with Free HER-2-targeting antibody, as the inhibitor. The cellular uptake of BNNT was compared with that observed in cells treated without Free HER-2-targeting antibody. (c) Subcellular distribution of the BNNT/β-glucan complex and BNNT/β-glucan-IgG complex in SK-OV-3 cells, as observed using confocal laser scanning microscopy. After 24 h of incubation with the BNNT/β-glucan-IgG complex and BNNT/β-glucan complex (red), lysosomes were stained with Lysotracker Green (green). Scale bar = 20 μm. (d) Efficacy of BNCT regarding cell viability in SK-OV-3 cells. The cells were incubated with the BNNT/β-glucan-IgG complex (blue), BNNT/β-glucan complex (red), or BPA-fructose (gray) for 24 h. After incubation, the cells were exposed to thermal neutron irradiation with a fluence of 6.3 × 10¹¹ n cm⁻². The cell viabilities were evaluated after additional incubation for 24 h.