Preparation of and Study on Magnetic Resonance Imaging Performance of Metal Porphyrin Modified by Low Molecular Weight Chitosan

The functional complex Mn-TCPP-CS20as a potential magnetic resonance imaging(MRI)contrast agent was synthesized through tetra(4-carboxyphenyl)Mn(Ⅱ)-porphyrin(Mn-TCPP)modified by CS20,which was low degree of polymerization and narrow distribution.The results showed that Mn-TCPP-CS20had good water-solubility and structural stability.The chemical structures of the products were characterized with Fourier transform infrared spectra(FTIR),UV-Vis spectra,mass spectrum(MS)and inductively coupled plasma atomic emission spectrometry(ICP-AES).The results showed that Mn-TCPP was successfully linked to CS20by an amide function.The relaxation properties in vitro of the functional complex Mn-TCPP-CS20as the potential MRI contrast agent were preliminarily studied.It was found that the longitudinal relaxivity(r1)of the synthesized Mn-TCPP-CS20(6.11mmol-1·L·s-1)was higher than that of the commercial contrast agent Gd-DTPA(r1=3.59mmol-1·L·s-1).Besides,the imaging effect of Mn-TCPP-CS20 was superior to that of Gd-DTPA in the same condition.These studies suggested that Mn-TCPP-CS20has the advantage of becoming apotential tissue-targeting contrast agent.