Institute for Lasers Photonics and Biophotonics, 458 Natural Sciences Complex, The University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, USA.
Nanoscale. 2012 Sep 7;4(17):5483-9. doi: 10.1039/c2nr31002c. Epub 2012 Aug 1.
Luminescent imaging agents and MRI contrast agents are desirable components in the rational design of multifunctional nanoconstructs for biological imaging applications. Luminescent biocompatible silicon quantum dots (SiQDs) and gadolinium chelates can be applied for fluorescence microscopy and MRI, respectively. Here, we report the first synthesis of a nanocomplex incorporating SiQDs and gadolinium ions (Gd³⁺) for biological applications. The nanoconstruct is composed of a PEGylated micelle, with hydrophobic SiQDs in its core, covalently bound to DOTA-chelated Gd³⁺. Dynamic light scattering reveals a radius of 85 nm for these nanoconstructs, which is consistent with the electron microscopy results depicting radii ranging from 25 to 60 nm. Cellular uptake of the probes verified that they maintain their optical properties within the intracellular environment. The magnetic resonance relaxivity of the nanoconstruct was 2.4 mM⁻¹ s⁻¹ (in terms of Gd³⁺ concentration), calculated to be around 6000 mM⁻¹ s⁻¹ per nanoconstruct. These desirable optical and relaxivity properties of the newly developed probe open the door for use of SiQDs in future multimodal applications such as tumour imaging.
发光成像剂和 MRI 对比剂是用于生物成像应用的多功能纳米结构合理设计的理想组成部分。发光生物相容性硅量子点 (SiQDs) 和钆螯合物可分别用于荧光显微镜和 MRI。在这里，我们报告了首例用于生物应用的将 SiQDs 和钆离子 (Gd³⁺) 结合的纳米复合物的合成。该纳米结构由聚乙二醇化胶束组成，其核心具有疏水性的 SiQDs，通过共价键与 DOTA 螯合的 Gd³⁺结合。动态光散射显示这些纳米结构的半径为 85nm，与电子显微镜结果一致，表明其半径范围为 25 至 60nm。探针的细胞摄取验证了它们在细胞内环境中保持其光学性质。该纳米结构的磁共振弛豫率为 2.4mM⁻¹s⁻¹（以 Gd³⁺浓度计），计算得到每个纳米结构约为 6000mM⁻¹s⁻¹。这种新开发探针的理想光学和弛豫率特性为 SiQDs 在未来的多模态应用（如肿瘤成像）中开辟了道路。
