Chelating DTPA amphiphiles: ion-tunable self-assembly structures and gadolinium complexes

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Nanotechnology

Background:

• Chelating amphiphiles based on diethylenetriaminepentaacetic acid (DTPA) were designed.
• These amphiphiles incorporate hydrophobic chains (oleyl or phytanyl) and can complex with gadolinium (Gd(III)).
• Gd(III) complexes are investigated for their potential as magnetic resonance imaging (MRI) contrast agents.

Purpose of the Study:

• To synthesize and characterize novel chelating amphiphiles and their Gd(III) complexes.
• To investigate the self-assembly and liquid crystalline phase behavior of these compounds in neat and hydrated states.
• To explore the influence of ionic strength and amphiphile structure on nanostructure formation.

Main Methods:

• Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) for thermal properties.
• Cross-polarizing optical microscopy (POM) for phase behavior.
• Small and wide-angle X-ray scattering (SWAXS) for structural analysis.

Main Results:

• Neat amphiphiles formed lamellar structures.
• Non-complexed amphiphiles exhibited diverse lyotropic phases influenced by chain structure and ionic strength.
• Gd(III) complexation led to lamellar crystalline structures in neat forms; hydrated Gd-complexed mono-conjugates formed micelles/vesicles, while bis-conjugates showed partial liquid crystalline mesophase formation.

Conclusions:

• The synthesized DTPA-based amphiphiles and their Gd(III) complexes display tunable self-assembly and liquid crystalline properties.
• Ionic strength and amphiphile design significantly impact the resulting nanostructures.
• These materials hold promise for applications in MRI contrast enhancement and advanced materials.