Lactosaminated N-succinyl-chitosan as a liver-targeted carrier of 99mTc in vivo for nuclear imaging and biodistribution

Lactosaminated N-succinyl-chitosan (LNSC), a water-soluble biodegradable derivative of chitosan, was prepared, characterized, and investigated for nuclear imaging and body distribution. The labeling efficiency of LNSC was examined with Tc-99m, and the obtained complex was used as liver-targeted delivery system in vivo for nuclear imaging, and its biodistribution within the body was studied. The labeling efficiency with Tc-99m was investigated for time of reaction, effect of substrate amount, effect of stannous chloride (SnCl2) concentration, and effect of the pH of the reaction mixture, in order to approach the optimum condition for labeling technique. It was found that the maximum yield for labeling of 25-mg Tc-99m-LNSC was 96.9% when SO mu g of SnCl2 was used at pH 3.5-5, at room temperature and 5-min reaction time. An in vivo biodistribution study of radiolabeled LNSC was carried out in female Wistar rats, and the body distribution profile was recorded by gamma scintigraphy. The biodistribution of Tc-99m-labeled LNSC (Tc-99m-LNSC) in each organ was calculated as a percentage of the injected dose per gram of tissue (%ID/g). Tc-99m-LNSC was shown to be a highly potential approach for liver imaging. Moreover, the rapid excretion of LNSC through the kidneys suggests that water-soluble chitosan derivatives are good carriers of radioactive elements that do not accumulate in the body. The results indicate that the easy and inexpensive extraction, and thus the ready availability, of chitosan and its derivatives makes them potentially useful for applications in scintigraphic imaging.