Fig. 3

A Intra-cartilage uptake ratios of CPCs in healthy, 20%, and 90% GAG depleted cartilage explants (* vs healthy explant) and their % retention within cartilage over a 7-day desorption period in 1× and 10× PBS. B Half cartilage disks are placed in a custom-designed transport chamber. 1-D diffusion of fluorescent solutes is allowed through the cartilage explant from the superficial zone (SZ) to the deep zone (DZ) for 24 h. A 100 μm slice is cut from the center of the explant and imaged in the X-Y plane to estimate the depth of penetration of solutes from SZ to DZ. The equilibrated explants are also desorbed in 1× PBS for 24 h and imaged to estimate retention of solutes in cartilage. Adapted with permission from [7, 13]. C Confocal images showing 1-D depth of penetration of free IGF-1, CPC, and dual-labeled CPC-IGF-1 conjugate in cartilage after 24 h absorption followed by 24 h desorption in 1× PBS with their respective penetration concentration profiles. The green channel shows IGF-1-FITC and the red channel shows CPC-Cy5. SZ is the superficial zone and DZ and deep zone