(A) Fluorescence emission spectra of blood collected from healthy mice at 6 and 48 hours post tail-vein injection with μNETs and nNETs (λex = 720 ± 2.5 nm) after baseline subtraction of blood emission spectra in SDS. (B) Estimated percentages of ICG recovered from mice blood after tail vein injection of ICG (circles ), μNETs (triangles ) and nNETs (diamonds ) as a function of time. The inset represents the estimated percentages of ICG recovered from mice blood for the three agents at 0 min, 5 min, 45 min, 2 and 6 hours respectively. Error bars represent standard deviations, and the single asterisk denotes statistically significant differences (p < 0.05) between the indicated pairs for all the time points.