Effect of Gd and Dy Concentrations in Layered Double Hydroxides on Contrast in Magnetic Resonance Imaging

Abstract

In this work, we explore the synthesis of layered double hydroxide (LDH) particles containing different molar ratios of Gd3+ and Dy3+ cations. A single crystalline phase was obtained for Zn2.0Al0.75Gd0.125Dy0.125-LDH and Zn2.0Al0.5Gd0.25Dy0.25-LDH, and their efficiency as contrast agents was evaluated by T1- and T2-weighted magnetic resonance imaging (MRI). Both GdDy-LDHs exhibited longitudinal relaxivity (r1) higher than a commercial reference. The highest contrast in the T1 mode was achieved with the Zn2.0Al0.75Gd0.125Dy0.125-LDH, which contained the lowest concentration of lanthanides; this efficiency is related to the lowest amount of carbonate anions complexing the lanthanide sites. On the contrary, the best contrast in the T2 mode was achieved with Zn2.0Al0.5Gd0.25Dy0.25-LDH. Zn2.0Al0.75Gd0.125Dy0.125-LDH and Zn2.0Al0.5Gd0.25Dy0.25-LDH presented r2/r1 ratios of 7.9 and 22.5, respectively, indicating that the inclusion of gadolinium and dysprosium into layered structures is a promising approach to the development of efficient bimodal (T1/T2) MRI contrast agents.

Surface modification of two-dimensional layered double hydroxide nanoparticles with biopolymers for biomedical applications

“…The first route is easily achievable due to ability to exchange layer forming cations with other ones of a similar radius, while the latter is feasible due to elevated LDH ionexchange capacity. Applications of LDH substances and their derivatives include bioimaging [121,147,185], cosmetic [186] and therapeutic applications [77,173], development of novel drug and gene delivery platforms [155,187], tissue engineering [188][189][190], material science [1,4,191] and various sensing schemes based on LDH nanoparticles [192][193][194]. Below, we will focus on those involving LDH-biopolymer hybrids during materials preparation or functionalization.…”

“…This may provide the diagnostic teams to better differentiate between diseased and healthy tissues to deliver more accurate results [120]. Another dual mode MRI contrast agent LDH was prepared by Andrade et al, who co-incorporated T 1 -type Gd(III) and T 2 -type Dy(III) within the LDH lamellae [121].…”

Layered double hydroxide-based nanomaterials for biomedical applications

“…Andrade et al prepared ZnAlGdDy-LDH with different Gd 3+ /Dy 3+ doping ratios (Zn 2.0 Al 0.75 Gd 0.125 Dy 0.125 -LDH and Zn 2.0 Al 0.5 Gd 0.25 Dy 0.25 -LDH) to evaluate their efficiency as contrast agents. 74 Relaxometry assessments showed that the best T 1 -weighted contrast was achieved with the former ( r 2 / r 1 ratio is 7.9), while the highest T 2 -weighted contrast was achieved with the latter ( r 2 / r 1 ratio is 22.5). Both of them displayed higher r 1 relaxivity than a commercial reference, indicating their potential to construct bimodal MRI contrast agents.…”

“…Andrade et al successfully prepared Gd/Dy-doped ZnAl-LDHs by this method. 74 Briefly, an aqueous solution containing hydrated nitrate salts of Zn, Al, Gd, and Dy was titrated with NH 4 OH under vigorous stirring. The final pH value of the solution was maintained at 10.0 and the resulting slurry was aged at room temperature for 24 h. The GdDy-doped ZnAl-LDHs were obtained after being washed with deionized water.…”

Quantitative Analysis of Electrical Current Effect on Magnetic Resonance Image Tissue Intensity

“…The paramagnetic effect of Gd in contrast enhancement of MRI images is by decreasing the relaxation times of T2 and T1 on protons. With the use of iron oxide, the dephasing rate of T2 * increases as well as T2 and T1 in the protons [7,8,9].…”