Enhancement of Relaxivity Rates of Gd–DTPA Complexes by Intercalation into Layered Double Hydroxide Nanoparticles

Abstract

In this paper we report the preparation and characterization of [Gd(dtpa)](2-) intercalated layered double hydroxide (LDH) nanomaterials. [Gd(dtpa)](2-) (gadolinium(III) diethylene triamine pentaacetate) was transferred into LDH by anionic exchange. The intercalation of [Gd(dtpa)](2-) into LDH was confirmed by X-ray diffraction for the new phase with the interlayer spacing of 3.5-4.0 nm and by FTIR for the characteristic vibration peaks of [Gd(dtpa)](2-). The morphology of the nanoparticles was influenced by the extent of [Gd(dtpa)](2-) loading, in which the poly-dispersity quality decreased as the [Gd(dtpa)](2-) loading was increased. Compared with the morphology of the original Mg(2)Al-Cl-LDH nanoparticles (hexagonal plate-like sheets of 50-200 nm), the modified LDH-Gd(dtpa) nanoparticles are bar-like with a width of 30-60 nm and a length of 50-150 nm. LDH-Gd(dtpa) was expected to have an increased water proton magnetic resonance relaxivity due to the intercalation of [Gd(dtpa)](2-) into the LDH interlayer that led to slower molecular anisotropic tumbling compared with free [Gd(dtpa)](2-) in solution. Indeed, LDH-nanoparticle suspension containing approximately 1.6 mM [Gd(dtpa)](2-) exhibits a longitudinal proton relaxivity r(1) of approximately 16 mM(-1) s(-1) and a transverse proton relaxivity r(2) of approximately 50 mM(-1) s(-1) at room temperature and a magnetic field of 190 MHz, which represents an enhancement four times (r(1)) and 12 times (r(2)) that of free [Gd(dtpa)](2-) in solution under the same reaction conditions. We have thus tailored LDH-nanoparticles into a novel contrast agent with strong relaxivity, promising for great potential applications in magnetic resonance imaging.

Applications of Nanoparticles in Biology

“…Exogenous contrast agents are generally introduced to enhance the tissue contrast, including complexes of Gd III and magnetic nanoparticles. Complexes of Gd III in liposomes or micelles are widely used as a MRI contrast agents; [163] however, these sytems suffer from drawbacks such as Gd III ion exchange with endogenous metals (e.g., Zn, Cu), and uptake of complexes in extravascular space. The monodisperse, cross-linked iron oxide (CLIO) nanoparticles reported by Weissleder's group provide non-toxic MRI contrast agents.…”

Peroxidase‐Like Layered Double Hydroxide Nanoflakes for Electrocatalytic Reduction of H2O2

“…LDHs have been the subject of intense research in recent years because of their potential applications in a wide range of areas [2 -9] LDHs have been shown to be a biocompatible material with low cytotoxicity [11,12] and intense adsorbability, and those physical properties make them suitable as the underlying materials for immobilization of enzymes to fabricate biosensors [5,6,13,14]. Though LDHs possess those desirable properties, most LDHs have no electroactivity which limit their wide applications in electrochemistry.…”

Electrochemical Oxidation of Epinephrine and Uric Acid at a Layered Double Hydroxide Film Modified Glassy Carbon Electrode and Its Application

“…Layered double hydroxides (LDH), also called anionic clays, were reported to be an attractive material for electrochemical biosensor design [14 -17] attributing to its desirable properties, such as low cytotoxicity [18], intense adsorbability [19], and high thermal stability [20]. Very recently, we have prepared the Zn/Al LDH film modified glassy carbon electrode (LDHf/GCE) according to the method of electrodeposition on a gold electrode [21] for simultaneous determination of catechol and hydroquinone under coexistence of resorcinol [22].…”