Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 3 Research Link, Singapore 117602.
ACS Nano. 2013 Aug 27;7(8):6796-805. doi: 10.1021/nn401734t. Epub 2013 Jul 25.
The fluorescent probes having complete spectral separation between absorption and emission spectra (large Stokes shift) are highly useful for solar concentrators and bioimaging. In bioimaging application, NIR fluorescent dyes have a greater advantage in tissue penetration depth compared to visible-emitting organic dyes or inorganic quantum dots. Here we report the design, synthesis, and characterization of an amphiphilic polymer, poly(isobutylene-alt-maleic anhyride)-functionalized near-infrared (NIR) IR-820 dye and its conjugates with iron oxide (Fe3O4) magnetic nanoparticles (MNPs) for optical and magnetic resonance (MR) imaging. Our results demonstrate that the Stokes shift of unmodified dye can be tuned (from ~106 to 208 nm) by the functionalization of the dye with polymer and MNPs. The fabrication of bimodal probes involves (i) the synthesis of NIR fluorescent dye (IR-820 cyanine) functionalized with ethylenediamine linker in high yield, >90%, (ii) polymer conjugation to the functionalized NIR fluorescent dye, and (iii) grafting the polymer-conjugated dyes on iron oxide MNPs. The resulting uniform, small-sized (ca. 6 nm) NIR fluorescent dye-magnetic hybrid nanoparticles (NPs) exhibit a wider emissive range (800-1000 nm) and minimal cytotoxicity. Our preliminary studies demonstrate the potential utility of these NPs in bioimaging by means of direct labeling of cancerous HeLa cells via NIR fluorescence microscopy and good negative contrast enhancement in T2-weighted MR imaging of a murine model.
具有吸收光谱和发射光谱完全分离（大斯托克斯位移）的荧光探针对于太阳能聚光器和生物成像非常有用。在生物成像应用中，与可见发射有机染料或无机量子点相比，近红外（NIR）荧光染料在组织穿透深度方面具有更大的优势。在这里，我们报告了一种两亲聚合物聚（异丁烯-alt-马来酸酐）-功能化近红外（NIR）IR-820 染料及其与氧化铁（Fe3O4）磁性纳米粒子（MNPs）的轭合物的设计、合成和表征，用于光学和磁共振（MR）成像。我们的结果表明，通过聚合物和 MNPs 对染料进行功能化，可以调整未修饰染料的斯托克斯位移（从~106nm 调谐至 208nm）。双模态探针的制备涉及（i）以高收率（>90%）合成带有乙二胺连接基的近红外荧光染料（IR-820 菁染料），（ii）聚合物与功能化的近红外荧光染料的偶联，以及（iii）将聚合物偶联的染料接枝到氧化铁 MNPs 上。所得的均一、小尺寸（约 6nm）近红外荧光染料-磁性杂化纳米粒子（NPs）表现出更宽的发射范围（800-1000nm）和最小的细胞毒性。我们的初步研究表明，这些 NPs 通过近红外荧光显微镜对癌细胞进行直接标记，并在小鼠模型的 T2 加权磁共振成像中产生良好的负对比增强，在生物成像中具有潜在的应用价值。
