Fig. 2

Identification of inner ear-targeting peptides and validation of the ability to cross the BLB in vivo. a Amino acid sequences of the four candidate IETP peptides. b Ex vivo fluorescence imaging showing the uptake of the four IETP peptides in mouse cochleae. c In vivo imaging showing the accumulation of IETP2-Cy5.5 in mouse cochleae. Gly-Cy5.5 served as a negative control. d Kinetic analysis of IETP2 binding to LRP1. A dissociation constant (K_D) of 738 nM was obtained. e–i Immunofluorescence imaging of the mouse cochleae injected with Cy5.5. j–n Immunofluorescence imaging of mouse cochleae 50 min after the injection of IETP2-Cy5.5. Different regions (midturn, OC, SV, SGN and SP) were displayed, and immunostaining with anti-LRP1 antibody was performed. White arrows indicate regions of interest. o–x Immunofluorescence imaging of mouse cochleae 2 h after injection of IETP2-Cy5.5. q, s, v, w Zoomed-in immunofluorescence images of OC, SGN, SV, and SP (white rectangular area) in the mouse inner ear showing the colocalization of the receptor LRP1 and IETP2-Cy5.5 in IHCs, neurons, ECs and SP regions. y–z Microscopy images of the mouse cochleae SV injected with Cy5.5 or IETP2-Cy5.5 from a different perspective. Diffuse of IETP2-Cy5.5 into the intrastrial space was observed. DAPI: blue; LRP1: green; Cy5.5 and IETP2-Cy5.5: magenta or red. Scale bars: e, j, o 100 µm, y, z 50 µm, others 10 µm.)