Preparation of highly efficient MRI contrast agents through complexation of cationic Gd(III)-containing metallosurfactant with biocompatible polyelectrolytes

Novel contrast agents were developed through assembling of Gd(III) -containing metallosurfactant (MS) with biocompatible polyelectrolytes sodium hyaluronate (HA), heparinsodium (HS) and dextran sulfate sodium (DSS). The formed polyelectrolyte-surfactant complexes showed different structural patterns as the charge ratio increased, including spherical aggregates, rod-like aggregates and network patterns in monovalent HA system, while spherical structures emerged in multivalent HS and DSS systems. Energy dispersive spectroscopy analysis and scanning electron microscopy mapping showed the presence of Gd(III) in these complexes. Inductively coupled plasma atomic emission spectrometry was further used to quantify the contents of Gd(III) in the assemblies. T1 magnetic resonance imaging showed that these Gd(III) -loaded complexes exhibited relaxivity of up to 63.81 mM(-1) s(-1) , much higher than that of Ominiscan (4.64 mM(-1) s(-1) ). The cytotoxicity test in vitro demonstrated the excellent biocompatibility of these complexes, which is essential for clinical application.