Use of a genetically engineered protein for the design of a multivalent MRI contrast agent

Lindsay S. Karfeld, Steve R. Bull, Nicolynn E. Davis, Thomas J. Meade, Annelise E. Barron*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The majority of clinically used contrast agents (CAs) for magnetic resonance imaging have low relaxivities and thus require high concentrations for signal enhancement. Research has turned to multivalent, macromolecular CAs to increase CA efficiency. However, previously developed macromolecular CAs do not provide high relaxivities, have limited biocompatibility, and/or do not have a structure that is readily modifiable to tailor to particular applications. We report a new family of multivalent, biomacromolecular, genetically engineered protein polymer-based CAs; the protein backbone contains evenly spaced lysines that are derivatized with gadolinium (Gd(III)) chelators. The protein's length and repeating amino acid sequence are genetically specified. We reproducibly obtained conjugates with an average of 8-9 Gd(III) chelators per protein. These multivalent CAs reproducibly provide a high relaxivity of 7.3 mM-1 s-1 per Gd(III) and 62.6 mM-1 s-1 per molecule. Furthermore, they can be incorporated into biomaterial hydrogels via chemical cross-linking of the remaining free lysines, and provide a dramatic contrast enhancement. Thus, these protein polymer CAs could be a useful tool for following the evolution of tissue engineering scaffolds.

Original languageEnglish (US)
Pages (from-to)1697-1700
Number of pages4
JournalBioconjugate Chemistry
Issue number6
StatePublished - Nov 2007

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry

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