High relaxivity linear Gd(DTPA)-polymer conjugates: The role of hydrophobic interactions
High relaxivity linear Gd(DTPA)-polymer conjugates: The role of hydrophobic interactions
复制标题
DOI：
10.1002/mrm.1910380506
复制
发表时间：
1997-11-01
影响因子：
3.3
通讯作者：
Wei, D
中科院分区：
文献类型：
--
作者：
Kellar, KE;Henrichs, PM;Wei, D
合成了一系列DTPA类Gd ~（3+）共轭物的线性共聚物，这些共聚物由α，ω-烷基二酰胺与分隔酰胺官能团的不同数目（n）的亚甲基连接而成。在MRI场和35 ℃下，n = 10和n = 12聚合物的弛豫率出乎意料地高，类似于刚性树枝状聚合物基Gd 3+螯合物的弛豫率。对于无脲和含脲聚合物水溶液测量溶剂质子1/T-1的磁场依赖性，无尿素溶液的结果意味着刚性的增加（高弛豫率所需的）随着n的增加，由亚甲基与溶剂的疏水相互作用引起，这一假设得到了脲的加入后弛豫率大幅下降的支持，已知脲会削弱疏水相互作用。弛豫率也与聚合物浓度无关，表明疏水相互作用是分子内的。
A series of linear copolymers of DTPA-class Gd3+ conjugates, linked by alpha,omega-alkyldiamides with a varying number (n) of methylenes separating the amide function, were synthesized, Surprisingly, their relaxivities at all fields increased with increasing n. At MRI fields and 35 degrees C, the relaxivities of the n = 10 and n = 12 polymers were unexpectedly high, similar to those of rigid dendrimer-based Gd3+ chelates, The magnetic field dependence of solvent proton 1/T-1, was measured for aqueous urea-free and urea-containing polymer solutions, The results for urea-free solutions imply an increase of rigidity (required for high relaxivities) with increasing n, arising from hydrophobic interactions of the methylene groups with solvent, This hypothesis is supported by a large decrease in the relaxivities upon addition of urea, which is known to weaken hydrophobic interactions, The relaxivities are also independent of polymer concentration, indicating that the hydrophobic interactions are intramolecular.