Figure 1.

in vivo testing of recombinant radiotracers constructed by joining protein modules of PBT of VEGFA and Fc of IgG1. A. The domain architectures of constructed protein tracers, of which chimeric fusion PBT-Fc was selected for in-depth studies (highlighted by an asterisk). B. PBT-Fc expressed from E. coli. naturally existed as a dimer, as shown on SDS-PAGE under non-reducing condition (NR) when compared to reducing condition (R). C. Schematic illustrations of nephron (upper right) and proximal tubular epithelial cell (bottom left inset). The distinct intrarenal passages of individual tracers (1: Fc-alone; 2. PBT-Fc; and 3. Duramycin) including their interactions with corresponding cell receptors and ECM target(s) are shown (follow arrows). The steady phase location of each tracer is indicated by parentheses. D. Selected minute-by-minute planar scanning images of [^99mTc]-labeled Fc-alone, PBT-Fc and duramycin in anesthetized rats, showing distinct dynamic patterns of these tracers. Apparent heart/lung blood pool (blue arrow), the kidney (red arrow) and the bladder (green arrow) locations are indicated. E. Combined steady phase images between 40 and 60 min showed contrasting differences of systemic circulation, renal sequestration, and urinary excretion profiles for Fc-alone, PBT-Fc and duramycin tracers, respectively. The experiment was repeated 3 times and representative images are shown (n = 3).