Iatridi Zacharoula, Georgiadou Violetta, Menelaou Melita, Dendrinou-Samara Catherine, Bokias Georgios
Department of Chemistry, University of Patras, GR-26504 Patras, Greece.
Dalton Trans. 2014 Jun 21;43(23):8633-43. doi: 10.1039/c4dt00393d.
Hydrophobically modified water-soluble polymers (HMWSPs), comprised of a poly(sodium methacrylate) (PMANa) or poly(sodium acrylate) (PANa) backbone and pendent dodecyl methacrylate (DMA) or dodecyl acrylamide (DAAm) chains, respectively, were synthesized. The hydrophobic content of the copolymers, P(MANa-co-DMA) and P(ANa-co-DAAm), is in the range of 0 to 25 mol%, while their weight-average molar mass varies from ~10 000 up to ~75 000. Their self-assembly behavior in dilute aqueous solution was followed through Nile Red probing, DLS and TEM measurements. The critical micelle concentration (CMC) is mainly controlled by the hydrophobic content and not the molar mass of the copolymers. Above CMC, spherical and large-compound micelles are identified by DLS and TEM. Moreover, oleylamine coated CoFe2O4 nanoparticles (CoFe2O4@OAm MNPs) of 9.4 nm with a saturation magnetization Ms = 85 emu g(-1) were solvothermally prepared. The hydrophobic CoFe2O4@OAm MNPs were successfully encapsulated into the hydrophobic cores of the structures formed by the copolymers above CMC through a solvent mixing procedure, and in that way hydrophilic CoFe2O4@HMWSP nanohybrids resulted. For comparison purposes, two alternate phase transfer approaches were also used to convert CoFe2O4@OAm MNPs to hydrophilic ones: (a) addition of a coating layer by cetyltrimethyl ammonium bromide (CTAB) and (b) by the ligand exchange procedure with 2,3-dimercaptosuccinic acid (DMSA). NMR transverse relaxivity measurements of the aqueous suspensions of CoFe2O4@P(ANa-co-DAAm), CoFe2O4@CTAB and CoFe2O4@DMSA were recorded and the r2 relaxivity was determined. CoFe2O4@CTAB demonstrated the highest r2 relaxivity of 554.0 mM(-1) s(-1), while CoFe2O4@P(ANa-co-DAAm) and CoFe2O4@DMSA showed lower values of 313.6 mM(-1) s(-1) and 76.3 mM(-1) s(-1), respectively.
合成了疏水改性水溶性聚合物（HMWSPs），它们分别由聚（甲基丙烯酸钠）（PMANa）或聚（丙烯酸钠）（PANa）主链以及侧链甲基丙烯酸十二酯（DMA）或丙烯酰胺十二酯（DAAm）组成。共聚物P（MANa-co-DMA）和P（ANa-co-DAAm）的疏水含量在0至25摩尔％范围内，而它们的重均摩尔质量在约10000至约75000之间变化。通过尼罗红探测、动态光散射（DLS）和透射电子显微镜（TEM）测量跟踪了它们在稀水溶液中的自组装行为。临界胶束浓度（CMC）主要由疏水含量控制，而不是由共聚物的摩尔质量控制。在CMC以上，通过DLS和TEM鉴定出球形和大复合胶束。此外，通过溶剂热法制备了具有9.4nm粒径、饱和磁化强度Ms = 85 emu g(-1)的油胺包覆的CoFe2O4纳米颗粒（CoFe2O4@OAm MNPs）。通过溶剂混合程序，将疏水性CoFe2O4@OAm MNPs成功封装到上述CMC以上共聚物形成的结构的疏水核中，从而得到亲水性CoFe2O4@HMWSP纳米杂化物。为了进行比较，还使用了两种替代的相转移方法将CoFe2O4@OAm MNPs转化为亲水性纳米颗粒：（a）通过十六烷基三甲基溴化铵（CTAB）添加涂层，以及（b）通过与2,3-二巯基琥珀酸（DMSA）的配体交换程序。记录了CoFe2O4@P（ANa-co-DAAm）、CoFe2O4@CTAB和CoFe2O4@DMSA水悬浮液的核磁共振横向弛豫率测量值，并确定了r2弛豫率。CoFe2O4@CTAB表现出最高的r2弛豫率，为554.0 mM(-1) s(-1)，而CoFe2O4@P（ANa-co-DAAm）和CoFe2O4@DMSA的值较低，分别为313.6 mM(-1) s(-1)和76.3 mM(-1) s(-1)。
