Department of Chemistry, and Advanced Research Institute, Tongji University, Shanghai 200092, China.
Lab of Low-Dimensional Materials Chemistry, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China.
Biomaterials. 2015;53:349-57. doi: 10.1016/j.biomaterials.2015.02.101. Epub 2015 Mar 17.
This work described a proof of concept study of hybrid nanogel-based magnetic resonance contrast agents, SPIO@GCS/acryl/biotin@Mn-gel, abb. as SGM, for highly efficient, pH-responsive T1 and T2 dual-mode magnetic resonance imaging (MRI). SGM have been synthesized by assembling superparamagnetic iron oxide particles into polysaccharide nanoclusters, followed by in-situ reduction of the manganese species on the clusters and a final mild polymerization. The dual-mode SGM showed an interesting pH-responsiveness in in vitro MRI, with both T1 and T2 relaxivities turned "ON" in the acidic environment, along with an increase in the r1 and r2 relaxivity values by 1.7-fold (from 8.9 to 15.3 mM(-1) S(-1)) and 4.9-fold (from 45.7 to 226 mM(-1) S(-1)), due to desirable silencing and de-silencing effects. This interesting acidic-responsiveness was further verified in vivo with both significantly brightened signal of tumor tissue in T1-weighted MR images and a darkened signal in T2-weighted MR images 50 min post-injection of SGM. This smart hybrid nanogel may serve as a promising candidate for further studies of dual-mode (T1 and T2) contrast agents in MRI, due to its high stability, interesting pH-response mechanism and indicative imaging of tumors.
本工作描述了基于杂化纳米凝胶的磁共振对比剂 SPIO@GCS/acryl/biotin@Mn-gel（简称 SGM）的概念验证研究，用于高效、pH 响应的 T1 和 T2 双模态磁共振成像（MRI）。SGM 通过将超顺磁性氧化铁颗粒组装到多糖纳米簇中，然后在簇上原位还原锰物种，最后进行温和聚合来合成。双模态 SGM 在体外 MRI 中表现出有趣的 pH 响应性，在酸性环境中 T1 和 T2 弛豫率均“开启”，同时 r1 和 r2 弛豫率值分别增加了 1.7 倍（从 8.9 增加到 15.3 mM(-1)S(-1)) 和 4.9 倍（从 45.7 增加到 226 mM(-1)S(-1))，这是由于理想的沉默和去沉默效应。这种有趣的酸性响应性在体内也得到了进一步验证，在 SGM 注射后 50 分钟，肿瘤组织的 T1 加权 MR 图像信号明显增强，T2 加权 MR 图像信号变暗。由于其高稳定性、有趣的 pH 响应机制和肿瘤的指示性成像，这种智能杂化纳米凝胶可能成为 MRI 中双模态（T1 和 T2）对比剂进一步研究的有前途的候选物。
