Figure 6.

Immunoswitch particles remain at the injection site longer than soluble antibody. (a) Nude mice (n = 3/group) were injected with IR-labeled soluble antibody or immunoswitch particles at t = 0 h. Mice were imaged with a full body IR imager at t = 3, 24, 48, and 72 h post-injection. (b) Change in the mean gray value over time in the target ROI. Images from individual mice were normalized to the mean gray value at t = 3 h (see Methods section). An immediate decrease is observed after injection, followed by a consistent clearance rate. Clearance from the injection site is greater for soluble antibodies than immunoswitch particles at all time points: t_1/2,soluble = 15.2 h and t_{1/2,immunoswitch} = 84.5 h when fit to a one phase decay equation. Significance measured by two-way ANOVA with Bonferroni post-test (p < 0.0001, F_1,16 = 995.7 treatment variation). (c) C57BL/6 mice (n = 3) were injected with IR-labeled immunoswitch particles 8 days after B16-SIY inoculation. Tumor, spleen, tumor-draining lymph node, and contralateral lymph node were harvested 48 h after treatment. Immunoswitch particles are retained primarily in the tumor and tumor-draining lymph node. Values were recorded relative to the sensor’s maximum (i.e., 0–1 scale). Significance measured by two-way ANOVA with Tukey’s post-test (*p < 0.05, **p < 0.01,***p < 0.001).