Enhancement of Relaxivity Rates of Gd–DTPA Complexes by Intercalation into Layered Double Hydroxide Nanoparticles
✍ Scribed by Zhi Ping Xu; Nyoman D. Kurniawan; Perry F. Bartlett; Gao Qing Lu
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 220 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
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 ≈1.6 mM [Gd(dtpa)]^2−^ exhibits a longitudinal proton relaxivity r~1~ of ≈16 mM^−1^ s^−1^ and a transverse proton relaxivity r~2~ of ≈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.