title: Surface Modification of Gd Nanoparticles with pH-Responsive Block Copolymers for Use As Smart MRI Contrast Agents.
abstract: Despite recent advances in the understanding of fundamental cancer biology, cancer remains the second most common cause of death in the United States. One of the primary factors indicative of high cancer morbidity and mortality and aggressive cancer phenotypes is tumors with a low extracellular pH (pHe). Thus, the ability to measure tumor pHe in vivo using noninvasive and accurate techniques that also provide high spatiotemporal resolution has become increasingly important and is of great interest to researchers and clinicians. In an effort to develop a pH-responsive magnetic resonance imaging (MRI) contrast agent (CA) that has the potential to be used to measure tumor pHe, well-defined pH-responsive polymers, synthesized via reversible addition-fragmentation chain transfer polymerization, were attached to the surface of gadolinium-based nanoparticles (GdNPs) via a "grafting to" method after reduction of the thiocarbonylthio end groups. The successful modification of the GdNPs was verified by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and dynamic light scattering. The performance of the pH-responsive polymer modified GdNPs was then evaluated for potential use as smart MRI CAs via monitoring the relaxivity changes with changing environmental pH. The results suggested that the pH-responsive polymers can be used to effectively modify the GdNPs surface to prepare a smart contrast agent for MRI.
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: Liping
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Farquhar
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: Chixia
authors.initials: C
authors.lastname: Tian
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: James
authors.initials: J
authors.lastname: Ranville
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Boyes
mesh_terms: D003287:Contrast Media / Q000138:chemical synthesis / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry* / Q000627:therapeutic use; D006801:Humans; D008279:Magnetic Resonance Imaging; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry
chemical_list: D003287:Contrast Media; D011108:Polymers; D005682:Gadolinium
keywords: contrast agents; gadolinium nanoparticles; magnetic resonance imaging; pH-responsive polymers; surface modification