purity available and used without further purification. Metallic natural
Ca (99.999%) and Chelex 100 resin (50–100 mesh) were obtained
from Sigma-Aldrich (St. Louis, MO). (cRGD)2 was obtained
from Peptide International Inc. (Louisville, KY) and 2-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid (p-SCN-Bn-DOTA) was purchased
from Macrocyclics (Dallas, TX). Diamyl, amylphosphonate extraction
resin (UTEVA) was acquired from Eichrom Technologies LLC (Lisle, IL).
The rest of the materials and reagents were obtained from Thermo Fisher
Scientific (Fair Law, NJ). Water and all buffers were of Milli-Q grade
(resistivity > 18.2 MΩ·cm) and were treated with Chelex
100 resin to remove heavy metal contaminants.