title: Sol and gel states in peptide hydrogels visualized by Gd(III)-enhanced magnetic resonance imaging.
abstract: The hydrogels assembled from a pair of self-repulsive but mutually attractive decapeptides are visualized by magnetic resonance imaging (MRI). It is found that in the absence of Gd(III)-chelate, gelation has little effect on MRI signal intensity. In the presence of Gd(III)-chelate, gelation leads to significant changes in water relaxation and MR signal intensity. The sol to gel transition is best visualized by T2-weighted imaging using large echo time with the sol producing a bright spot and the gel producing a dark spot. MRI studies point to high local Gd(III)-chelate concentration. Small-angle X-ray scattering study indicates that this local enrichment of Gd(III)-chelate has two contributing processes: first, the aggregation of peptides into fibers; second, within peptide fibers, Gd(III)-chelate further aggregate into clusters. This work demonstrates that the status of peptide-based hydrogels can be visualized by MRI with the aid of covalently linked Gd(III)-chelates. This result has implications for monitoring peptide scaffolds in vivo.
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
authors.forename: Mahika
authors.initials: M
authors.lastname: Weerasekare
authors.forename: Marc B
authors.initials: MB
authors.lastname: Taraban
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Shi
authors.forename: Eun-Kee
authors.initials: EK
authors.lastname: Jeong
authors.forename: Jill
authors.initials: J
authors.lastname: Trewhella
authors.forename: Yihua Bruce
authors.initials: YB
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D005682:Gadolinium / Q000737:chemistry*; D020100:Hydrogels; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D012542:Scattering, Radiation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D020100:Hydrogels; D010455:Peptides; D005682:Gadolinium