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. Author manuscript; available in PMC: 2014 Aug 8.
Published in final edited form as: J Phys Chem C Nanomater Interfaces. 2013 Jul 17;117(31):10.1021/jp406909b. doi: 10.1021/jp406909b

Figure 5.

Figure 5

Mechanism of Gd(III)-Complex Graphene Oxide-induced proton relaxation. Gd(III)-DO3A-NH2 (q=2) or Gd(III)-DTPA-NH2 (q=1) was conjugated to either GO or reduced GO (rGO). Analysis of the NMRD profiles shows that these agents have higher relaxivities per q compared to Gd(III) GO as a result of their more optimized τM and slower local motion. The near-zero values of S2 suggest isotropic tumbling of Gd(III)-complexes on the GO surface. Consistent with the findings in Gd(III) Graphene, r2 prediction (r2,predicted / r2,measured ) using the fitted parameters is more accurate for Gd(III)-DO3A-GO than for its rGO counterpart. τM and q of the complexes were obtained from literature37 and assumed to remain unchanged post-conjugation.