In vivo Cy5-EK1 distribution imaging

Six Balb/c female mice (8 weeks old) were randomly assigned to two groups and nasally administered with 20 μg of Cy5-EK1 in 50 μl of PBS (n = 3) or 50 μl of PBS without peptide (n = 3) as control for background fluorescence measurement. One hour later, mice were imaged for distribution of Cy5-EK1 by the IVIS Lumina K Series III in vivo imaging system (PerkinElmer, Waltham, MA, USA). Mice were euthanized by intraperitoneal injection of sodium pentobarbital to obtain the lungs, livers, kidneys, spleens, and hearts for imaging and measuring their fluorescence value. The relevant radiant efficiency (P s⁻¹ cm⁻² sr⁻¹) (μW⁻¹ cm²) was then calculated by Living Image 4.4 software (56 (link), 71 (link), 72 (link)).