Human Transthyretin with a Tailored Gd(III) Complex as a High-Relaxivity MRI Contrast Agent.

Area of Science:

• Biomaterials Science
• Nanotechnology
• Medical Imaging

Background:

• Protein-based biomaterials offer versatile platforms for medical applications, including drug delivery and diagnostics.
• Human transthyretin (TTR) is a potential drug carrier due to its biocompatibility and structure.

Purpose of the Study:

• To create a novel protein-based Magnetic Resonance Imaging (MRI) contrast agent.
• To functionalize TTR with a paramagnetic gadolinium complex (Gd-C4-IA) for enhanced MRI properties.

Main Methods:

• Conjugation of Gd-C4-IA to TTR via cysteine residues.
• Confirmation of conjugation using 1H NMR paramagnetic broadening and ICP-MS.
• Analysis of 1H nuclear magnetic relaxation dispersion (NMRD) profiles to assess relaxivity.

Main Results:

• Successful covalent attachment of Gd-C4-IA to TTR was confirmed.
• The TTR-Gd-C4-IA conjugate exhibited significantly enhanced relaxivity compared to the free complex.
• Relaxivity was optimized for clinical magnetic fields, influenced by water exchange, rotational dynamics, and Gd(III) loading.

Conclusions:

• The TTR-Gd-C4-IA conjugate is a promising biocompatible platform for MRI contrast enhancement.
• This approach highlights the potential of Gd-C4-IA as an efficient tag for protein-based biomaterials.
• The conjugate could serve dual roles in diagnostics and drug delivery.