A conjugated polymer - Gd (III) complex as pH sensitive contrast agent in magnetic resonance
imaging

doi:10.1007/s11458-010-0108-6

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Front. Chem. China ›› 2010, Vol. 5 ›› Issue (2) : 166-170. DOI: 10.1007/s11458-010-0108-6

Research articles

A conjugated polymer - Gd (III) complex as pH sensitive contrast agent in magnetic resonance imaging

Qingling XU¹,Libing LIU¹,Minghui YU¹,Qiong YANG¹,Shu WANG¹,Litao ZHU²,

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Abstract

A novel pH-responsive contrast agent (PFP-aa/Gd) for magnetic resonance imaging (MRI) was prepared by binding Gd(III) to a water-soluble conjugated polyfluorene with pendant carboxylate and amine moieties. The PFP-aa is a good chelator for Gd³⁺ and the PFP-aa/Gd complex has good stability. As the pH changes from 10.0 to 4.0, both the carboxylate and amine are protonated, thus PFP-aa exhibits positive charges and forms tight aggregation, which reduces molecular tumbling and accelerates the exchange of bound water leading to the increase of relaxivity R₁. More importantly, the R₁ increases by about eight fold as the pH changes from 8.0 to 6.0, which makes PFP-aa/Gd suitable as a potential marker of the pH below physiological level. In comparison to other contrast agents, the unique sensitivity of the water relaxivity of PFP-aa/Gd indicates that this complex could be used in MRI experiments to monitor physiological pH change.

Keywords

magnetic resonance imaging / pH-sensitive / conjugated polymer / Gd(III) chelate

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Qingling XU, Libing LIU, Minghui YU, Qiong YANG, Shu WANG, Litao ZHU,. A conjugated polymer - Gd (III) complex as pH sensitive contrast agent in magnetic resonance imaging. Front. Chem. China, 2010, 5(2): 166‒170 https://doi.org/10.1007/s11458-010-0108-6