Reduction-Driven Modulation of Relaxivity in Graphene Oxide Derivatives

Area of Science:

• Biomedical Engineering
• Materials Science
• Nanotechnology

Background:

• Graphene oxide (GO)-based nanomaterials are explored for biomedical applications, especially as carriers for magnetic resonance imaging (MRI) contrast agents (CAs).
• Optimizing the MRI performance of reduced graphene oxide (rGO) requires understanding the impact of reduction degree on its properties.

Purpose of the Study:

• To investigate the MRI contrast agent performance of reduced graphene oxide (rGO) materials.
• To determine the relationship between the degree of reduction and the MRI relaxivity of GO-based nanomaterials.

Main Methods:

• Graphene oxide (GO) synthesized via modified Hummers' method, followed by mild thermal (rGO1) and chemical (rGO2) reduction.
• Comprehensive physicochemical characterization using FTIR, Raman, XPS, DSC, and TGA.
• MRI relaxivity assessment at 1.0 T, complemented by EPR and ICP-MS for impurity analysis.

Main Results:

• MRI relaxivities significantly increased with a higher degree of reduction.
• Chemically reduced rGO2 showed a 3.9-fold increase in longitudinal (r1) and 4.6-fold increase in transverse (r2) relaxivity compared to GO.
• Strong correlations between relaxivities and structural parameters (C/O ratio, C-C/C=C content) indicate defects govern performance.

Conclusions:

• The degree of reduction critically influences the MRI contrast performance of graphene oxide-based nanomaterials.
• Controlled reduction offers a pathway for rational design of enhanced rGO-based MRI contrast agents.
• Optimized rGO materials hold promise for improved biomedical imaging and translation.