A New High-Performance Gadonanotube-Polymer Hybrid Material for Stem Cell Labeling and Tracking by MRI

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Gadonanotubes (GNTs) offer potential as MRI contrast agents but suffer from poor water dispersibility.
• Surface modification is crucial for improving the biocompatibility and application range of nanomaterials.

Purpose of the Study:

• To develop a gentle and rapid method for coating GNTs with polyacrylic acid (PAA).
• To enhance the water dispersibility and MRI contrast capabilities of GNTs.
• To evaluate the utility of the modified GNTs for cell labeling in MRI.

Main Methods:

• A polyacrylic acid (PAA) polymer coating was applied to gadonanotubes (GNTs) using a facile method.
• The dispersibility of the resulting PAA-GNT hybrid material in water was assessed at physiological pH.
• The MRI contrast properties (T1-weighted relaxivity) of PAA-GNTs were measured.
• Porcine bone-marrow-derived mesenchymal stem cells were labeled with PAA-GNTs.

Main Results:

• The PAA coating significantly improved GNT dispersibility in water to approximately 20 mg·mL^-1 without surfactants.
• The PAA-GNT material exhibited a high T1-weighted relaxivity of 150 mM^-1·s^-1 per Gd³⁺ ion at 1.5 T.
• Labeled stem cells showed excellent image contrast in phantom MRI experiments.
• Transmission electron microscopy confirmed the presence of dispersed PAA-GNTs within labeled cells (10¹⁴ Gd³⁺ ions per cell).

Conclusions:

• The developed PAA-GNT hybrid material demonstrates superior water dispersibility and potent MRI contrast capabilities.
• PAA-GNTs are effective and safe for labeling mesenchymal stem cells for MRI.
• This approach offers a promising strategy for developing advanced nanomaterials for biomedical imaging.