Figure 5.

In vivo biomaterial localization with Gd-labeled peptide nanofibers. (A) Schematic illustration of the ‘clicking’ of Gd(HPN₃DO3A) to the alkyne peptoid. Chemical structure of the self-assembling MRI contrast agents PA1–PA4. (B) Cartoon of self-assembled nanofibers of PA1. In vivo evaluation of PA1 and PA3: (C) 4 uL of PA gels were injected into each of six wild-type mice (injection point indicated by white arrows), and anatomical scan of mouse legs was performed immediately upon injection (top row) and after 4 days (bottom row). PA1 produced positive contrast in T₁ weighted MRI, while PA3 produced negative contrast in T₂ weighted MRI. (D) Average T₁ times from the region of interest and the background measured several millimeters from the PA injection site). PA1 possessed the shortest T₁ time (highest r₁ relaxivity). (Reproduced with permission from 29. Copyright 2014 American Chemical Society)