Pothayee Nipon, Balasubramaniam Sharavanan, Pothayee Nikorn, Jain Neeta, Hu Nan, Lin Yinnian, Davis Richey M, Sriranganathan Nammalwar, Koretsky Alan P, Riffle J S
Macromolecules and Interfaces Institute, Virginia Tech, Blacksburg, VA.
Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, MD.
J Mater Chem B. 2013;1(8):1142-1149. doi: 10.1039/C2TB00275B.
Magnetic Block Ionomer Clusters () with hydrophilic ionic cores and nonionic coronas have been prepared that have ultrahigh transverse NMR relaxivities together with capacities for incorporating high concentrations of polar antibiotic payloads. Magnetite-polymer nanoparticles were assembled by adsorbing the polyacrylate block of an aminofunctional poly(ethylene oxide--acrylate) (HN-PEO--PAA) copolymer onto magnetite nanoparticles. The PEO blocks extended into aqueous media to keep the nanoparticles dispersed. Amines at the tips of the HN-PEO corona were then linked through reaction with a PEO diacrylate oligomer to yield where the metal oxide in the precursor nanoparticles were distinctly separated by the hydrophilic polymer. The intensity average spacing between the magnetite nanoparticles within the clusters was estimated to be ~50 nm. These with hydrophilic intra-cluster space had transverse relaxivities () that increased from 190 to 604 s mM Fe measured at 1.4 T and 37 °C as their average sizes increased. The clusters were loaded with up to ~38 wt% of the multi-cationic drug gentamicin. MRI scans focused on the livers of mice demonstrated that these are sensitive contrast agents.
已制备出具有亲水性离子核和非离子冠层的磁性块状离聚物簇（），其具有超高的横向核磁共振弛豫率以及容纳高浓度极性抗生素负载的能力。通过将氨基官能化聚（环氧乙烷 - 丙烯酸酯）（HN - PEO - PAA）共聚物的聚丙烯酸酯嵌段吸附到磁铁矿纳米颗粒上，组装了磁铁矿 - 聚合物纳米颗粒。PEO嵌段延伸到水介质中以保持纳米颗粒分散。然后通过与PEO二丙烯酸酯低聚物反应，连接HN - PEO冠层末端的胺，得到其中前体纳米颗粒中的金属氧化物被亲水性聚合物明显隔开的产物。簇内磁铁矿纳米颗粒之间的强度平均间距估计为~50 nm。这些具有亲水性簇内空间的产物，其横向弛豫率（）在1.4 T和37°C下测量时，随着平均尺寸的增加，从190增加到604 s mM Fe。这些簇负载了高达约38 wt%的多阳离子药物庆大霉素。聚焦于小鼠肝脏的MRI扫描表明，这些是敏感的造影剂。
