Size-Dependent Cascade Enhancement of T₁-T₂ Dual-Modal MRI in Tumors

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Medical Imaging

Background:

• Uncertainty exists regarding the size-dependent T1 and T2 signal enhancement of in situ self-assembled Gadolinium (Gd) nanostructures.
• The potential for size adjustment to achieve enhanced T1-T2 dual-modal MRI remains unclear.

Purpose of the Study:

• To investigate the relationship between the size of in situ formed Gd nanostructures and their T1/T2 MRI contrast enhancement capabilities.
• To develop a strategy for achieving size-dependent T1-T2 dual-modal MRI for enhanced tumor imaging.

Main Methods:

• A two-step in situ self-assembly strategy was employed, starting with a small nanoprobe (Gd-TCO-P).
• Intracellular self-assembly, triggered by alkaline phosphatase (ALP) cleavage, formed Gd-nanofibers (Gd-NFs).
• Tetrazine-tetrazine crosslinking further assembled Gd-NFs into larger dendritic nanofibers (Gd-TS-NFs).

Main Results:

• The study achieved size-dependent enhancement of both T1 and T2 MRI signals through controlled in situ self-assembly.
• In vitro and in vivo experiments validated the enhanced contrast capabilities of the developed Gd nanostructures.
• The strategy enabled precise long-term imaging of ALP-overexpressing tumors.

Conclusions:

• In situ self-assembled Gd nanostructures exhibit size-dependent T1 and T2 MRI contrast enhancement.
• This approach offers a promising strategy for clinical applications of T1-T2 dual-modal MRI.
• The findings provide valuable insights into optimizing Gd nanostructures for advanced medical imaging.