Improving Longitudinal Transversal Relaxation Of Gadolinium Chelate Using Silica Coating Magnetite Nanoparticles

Abstract

Introduction and objective

Precisely and sensitively diagnosing diseases especially early and accurate tumor diagnosis in clinical magnetic resonance (MR) scanner is a highly demanding but challenging task. Gadolinium (Gd) chelate is the most common T₁ magnetic resonance imaging (MRI) contrast agent at present. However, traditional Gd-chelates are suffering from low relaxivity, which hampers its application in clinical diagnosis. Currently, the development of nano-sized Gd based T₁ contrast agent, such as incorporating gadolinium chelate into nanocarriers, is an attractive and feasible strategy to enhance the T₁ contrast capacity of Gd chelate. The objective of this study is to improve the T₁ contrast ability of Gd-chelate by synthesizing nanoparticles (NPs) for accurate and early diagnosis in clinical diseases.

Methods

Reverse microemulsion method was used to coat iron oxide (IO) with tunable silica shell and form cores of NPs IO@SiO₂ at step one, then Gd-chelate was loaded on the surface of silica-coated iron oxide NPs. Finally, Gd-based silica coating magnetite NPs IO@SiO₂-DTPA-Gd was developed and tested the ability to detect tumor cells on the cellular and in vivo level.

Results

The r₁ value of IO@SiO₂-DTPA-Gd NPs with the silica shell thickness of 12 nm was about 33.6 mM⁻¹s⁻¹, which was approximately 6 times higher than Gd-DTPA, and based on its high T₁ contrast ability, IO@SiO₂-DTPA-Gd NPs could effectively detect tumor cells on the cellular and in vivo level.

Conclusion

Our findings revealed the improvement of T₁ relaxation was not only because of the increase of molecular tumbling time caused by the IO@SiO₂ nanocarrier but also the generated magnetic field caused by the IO core. This nanostructure with high T₁ contrast ability may open a new approach to construct high-performance T₁ contrast agent.

Keywords:

• gadolinium chelate
• silica
• iron oxide
• nanoparticles
• T₁ relaxivity
• tumbling time

Acknowledgments

This work was supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 81571660 and 81601607) and the National Natural Science Foundation of China (NSFC) (Grant No. 81871421).

Disclosure

The authors report no conflicts of interest in this work.