作者：Guang Hui Gao , Jae Won Lee , Minh Khanh Nguyen , Geun Ho Im , Jehoon Yang , Hyejung He
关键字：pH-responsive Polymeric micelle Iron oxide nanoparticles Contrast agent Magnetic resonance imaging
论文来源：期刊
具体来源：Journal of Controlled Release
发表时间：2011年

A series of pH-responsive polymeric micelles is developed to act as intelligent carriers to deliver iron oxide

(Fe3O4) nanoparticles and respond rapidly to an acidic stimuli environment for magnetic resonance imaging

(MRI). The polymeric micelle can be self-assembled at physiological pH by a block copolymer, consisting of a

hydrophilic methoxy poly(ethylene glycol) (PEG) and a pH-responsive poly(β-amino ester)/(amido amine)

block. Consequently, the Fe3O4 nanoparticles can be well encapsulated into polymeric micelles due to the

hydrophobic interaction, shielded by a PEG coronal shell. In an acidic environment, however, the pH-

responsive component, which has ionizable tert-amino groups on its backbone, can become protonated to be

soluble and release the hydrophobic Fe3O4 nanoparticles. The Fe3O4-loaded polymeric micelle was measured

by dynamic light scattering (DLS), superconducting quantum interference device (SQUID) and a 3.0 T MRI

scanner. To assess the ability of this MRI probe as a pH-triggered agent, we utilize a disease rat model of

cerebral ischemia that produces acidic tissue due to its pathologic condition. We found gradual accumulation

of Fe3O4 nanoparticles in the brain ischemic area, indicating that the pH-triggered MRI probe may be effective

for targeting the acidic environment and diagnostic imaging of pathologic tissue.