Preparation and Relaxivity of Folate-mediated Targeting Gd~(3+) Contrast Agent

Under weak base condition, Bovine serum albumin (BSA) was reacted with the activated folate firstly; then the conjugates were coupled with Diethylene triamine pentaacetic dianhydride (cDTPAA) to form Folate-BSA-DTPA; finally, these coupled compounds were chelated with GdCl3. All complexes were characterized by UV, the ratios of folate and Gd-DTPA to BSA were determined by UV and ICP-AES methods, respectively. The spin-lattice relaxivity of the Gd complexes in vitro was analyzed. As a result, the ratio of folate to BSA was about 5, and the relaxivity was about 6×10-3 L·mmol-1·ms-1 enhanced three times compared to the small molecular Gd-DTPA, though there was no difference in relaxivity between folate-BSA-(Gd-DTPA)n and BSA-(Gd-DTPA)n.