Extracellular biodegradable macromolecular gadolinium(III) complexes for MRI.

Area of Science:

• Biomedical Imaging
• Materials Science
• Radiochemistry

Background:

• Macromolecular gadolinium (Gd) complexes are MRI contrast agents.
• Slow excretion and toxic Gd ion accumulation limit their clinical use.
• Biodegradable alternatives are needed to improve safety and efficacy.

Purpose of the Study:

• To design and prepare biodegradable polydisulfide-based macromolecular Gd(III) complexes.
• To evaluate their degradation, contrast enhancement, and excretion properties.
• To assess their potential for improved MRI applications.

Main Methods:

• Synthesis of polydisulfide-based macromolecular Gd(III) complexes.
• In vitro degradation studies using cysteine and human serum albumin (HSA).
• In vivo studies in rats to assess contrast enhancement, biodistribution, and excretion via mass spectrometry.

Main Results:

• Polydisulfide agents readily degraded by cysteine in vitro.
• No cross-reaction observed with human serum albumin (HSA).
• Concentration-dependent blood pool contrast enhancement observed; high molecular weight agent effective at low doses.
• In vivo degradation confirmed by mass spectrometry of urine samples, indicating renal filtration.

Conclusions:

• Novel biodegradable macromolecular Gd agents demonstrate in vitro and in vivo degradability.
• These agents provide superior blood pool contrast enhancement and rapid renal clearance.
• The developed agent shows significant potential for preclinical and clinical development in MRI contrast enhancement.