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Enhancing 29Si Hyperpolarization Efficiency in Silica Nanoparticles via Multishell Design with Selective 29Si-Isotope
Quynh Thi Nguyen1, Quy Son Luu2, Katsuaki Suzuki3
1Department of Applied Chemistry, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 15588, South Korea.
Analytical Chemistry
|July 2, 2025
Summary
Researchers developed novel multilayered silica nanoparticles (SiO2 NPs) for enhanced hyperpolarized 29Si MRI. Strategic enrichment of silicon-29 (29Si) and radicals significantly boosted signal amplification for advanced medical imaging.
Area of Science:
- Nanotechnology
- Materials Science
- Biomedical Imaging
Background:
- Silica nanoparticles (SiO2 NPs) are explored as probes for hyperpolarized 29Si MRI and MRS.
- Dynamic Nuclear Polarization (DNP) enhances 29Si MR signals but is limited by intrinsic defects in SiO2 NPs.
- Improving hyperpolarization efficiency is key for advanced MRI applications.
Purpose of the Study:
- To design and synthesize multilayered SiO2 NPs (core@shell@shell) for improved 29Si hyperpolarization.
- To investigate the effect of selective 29Si isotope and TEMPO radical enrichment on DNP efficiency.
- To evaluate the potential of these engineered nanoparticles as 29Si MRI probes.
Main Methods:
- Fabrication of multilayered SiO2 NPs with controlled 29Si isotope and TEMPO radical distribution.
- Application of solvent-free direct-polarization DNP-magic angle spinning.
- Measurement of 29Si hyperpolarized signal enhancement and spin diffusion length.
Main Results:
- Multilayered SiO2 NPs with selective enrichment demonstrated significantly improved 29Si hyperpolarized signals compared to conventional particles.
- Homogeneous enrichment yielded the highest signal enhancement, up to 25 times in direct-polarization DNP.
- Spin diffusion length was determined to be between 0.6–1.4 nm, with hyperpolarization localized in radical-enriched regions.
Conclusions:
- The strategic positioning and density of 29Si nuclei relative to radicals are critical for maximizing hyperpolarization.
- Designed nanoparticles allow detailed analysis of surface and core regions without radical removal.
- These engineered SiO2 NPs show promise as effective probes for 29Si MRI.
