Design and Synthesis of Gd(3+) Based MRI Contrast Agents

Magnetic Resonance Imaging (MRI) has become a prominent imaging technique in medicine.MRI contrast agents are used to increase the sensitivity of this technique.1,4,7,10-teraazacyclododecane (cyclen) is a key macrocycle used for the synthesis of Magnetic Resonance Imaging (MRI) contrast agents. Substituting the hydrogen atoms (attached to the nitrogen atoms in the ring) of cyclen with suitable groups produce stable ligands. These ligands on complexation with Ln3+ ions lead to the formation of useful chelates. Cyclen is widely synthesized via Richman and Atkins method.Recently, a new method for cancer treatment with a less side effect called photodynamic therapy (PDT) has been introduced. In this method cancer tissues are selectively destroyed without injuring the surrounding healthy cells. However, for the successful use of this method, the selection of an appropriate photosensitizer is important. Hence, it diagnosis-treat union of MRI and PDT will be significantly promoted if a new family of bi-functional agents is found, which would combine the effects of a contrast agent in MRI and of a photosensitizer in PDT. It will bring great improvement to the cancer diagnosis and treatment