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Updated: May 30, 2026
Magnetic and Thermal-sensitive Poly(N-isopropylacrylamide)-based Microgels for Magnetically Triggered Controlled Release
Published on: July 4, 2017
PEGylated silica nanoparticles encapsulating multiple magnetite nanocrystals for high-performance microscopic
Si-Han Wu1, Chien-Yuan Lin, Yann Hung
1Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Abstract:
A novel magnetic resonance (MR) angiographic method, 3DΔR2-mMRA (three dimensional and ΔR2 based microscopy magnetic resonance angiography), is developed as a clinical diagnosis for depicting the function and structure of cerebral small vessels. However, the visibility of microvasculatures and the precision of cerebral blood volume calculation greatly rely on the transverse relaxivity and intravascular half-life of contrast agent, respectively. In this work, we report a blood pool contrast agent named H-Fe₃O₄@SiO₂-PEG where multiple Fe₃O₄ nanocrystals are encapsulated in a thin silica shell to enhance the T₂-relaxivity (r₂ = 342.8 mM⁻¹ s⁻¹) and poly(ethylene glycol) (PEG) is employed to reduce opsonization and prolong circulation time of nanoparticles. Utilization of the newly developed H-Fe₃O₄@SiO₂-PEG with a novel MR angiographic methodology, a high-resolution MR image of rat cerebral microvasculatures is successfully obtained.
Insights
Researchers developed a new magnetic resonance angiography method and a novel blood pool contrast agent (H-Fe₃O₄@SiO₂-PEG) for improved visualization of cerebral microvasculatures.
Area of Science:
- Biomedical Engineering
- Nanotechnology
- Medical Imaging
Background:
- Cerebral small vessel imaging is crucial for clinical diagnosis.
- Current methods face limitations in microvasculature visibility and cerebral blood volume calculation accuracy.
- These limitations are linked to the performance of contrast agents.
Purpose of the Study:
- To develop a novel magnetic resonance (MR) angiographic method, 3DΔR2-mMRA, for depicting cerebral small vessel function and structure.
- To create an improved blood pool contrast agent to enhance MR angiography performance.
Main Methods:
- Development of a novel MR angiographic technique: 3DΔR2-mMRA.
- Synthesis of a blood pool contrast agent, H-Fe₃O₄@SiO₂-PEG, featuring Fe₃O₄ nanocrystals within a silica shell and PEG coating.
- Evaluation of the contrast agent's T₂-relaxivity and circulation time.
- Application of the new method and contrast agent in high-resolution MR imaging of rat cerebral microvasculatures.
Main Results:
- The H-Fe₃O₄@SiO₂-PEG contrast agent demonstrated high T₂-relaxivity (r₂ = 342.8 mM⁻¹ s⁻¹).
- PEGylation of the nanoparticles effectively reduced opsonization and prolonged circulation time.
- High-resolution MR images of rat cerebral microvasculatures were successfully obtained using the novel method and contrast agent.
Conclusions:
- The developed H-Fe₃O₄@SiO₂-PEG contrast agent and 3DΔR2-mMRA method significantly improve the visualization of cerebral microvasculatures.
- This advancement holds potential for enhanced clinical diagnosis of cerebrovascular diseases.
