In Vivo Imaging of Peptide Biodistribution

Six pregnant ICR mice (10–12 weeks old, E12–14) were assigned randomly to two groups and injected intravenously with 100 μg Z2-Cy5 in 100 μl PBS (n=3) or 100 μl PBS without peptide (n=3) as control (for background fluorescence measurement). One hour later, mice were imaged for distribution of Z2-Cy5 by the IVIS lumina K series III in vivo imaging system (PerkinElmer, Waltham, MA) and the radiant efficiency (p s⁻¹ cm⁻² sr⁻¹)(μW⁻¹ cm²) was calculated by Living image 4.4 software63 (link). To determine the distribution of Z2-Cy5 in organs, all pregnant mice were killed by intraperitoneal injection of sodium pentobarbital and the dissected livers, kidneys, spleens, hearts, uteruses and fetuses were imaged and the average radiant efficiency was calculated. The fetuses in the uteruses of two groups were applied to PFA-fixed paraffin sections to demonstrate the distribution of Z2 in the placenta and fetus.