Semiconductor Nanocrystals for Biomedical Imaging

第一阶段的主要目标是演示用于细胞成像的发光纳米粒子（量子点，QDs）的稳定和功能化方法。这将通过将量子点封装在两种不同类型的水溶性聚合物递送载体中来实现。这两种类型的聚合物最终将功能化与特定的靶向配体，以促进选定的细胞目标的成像。使量子点非常适合这种成像应用的物理化学性质包括：它们的量子产率，小尺寸，窄发射波长，在多尺寸的量子点标签之间影响很少或没有光谱重叠，它们的光稳定性，以及它们非常高的吸收效率，从而消除了对激发的高功率要求。在第一阶段，我们将合成聚合物并使用它们来封装定义直径的量子点。每个纳米颗粒复合物将在发光剖面、量子产率、光稳定性和消光系数方面进行表征。这些性质将在各种环境中进行检查，以确定荧光行为的任何pH或溶剂依赖方面。这两种类型的封装纳米颗粒探针将用于转染培养的哺乳动物细胞，以评估生理环境下的量子点发光。

The principal objective in Phase I is to demonstrate methodologies for the stabilization and functionalization of luminescent nanoparticles (quantum dots, QDs) to be used in cellular imaging. This will be achieved by encapsulating QDs in two different types of water-soluble polymer delivery vehicles. Both types of polymer will eventually be functionalized with specific targeting ligands in order to facilitate imaging of selected cellular targets. The physicochemical properties that make QDs well suited for such imaging applications include: their quantum yields, small size, narrow emission wavelengths which effect little or no spectral overlap among multiple-size QD tags, their photostability, and their very high absorption efficiencies which obviate the need for high power requirements for excitation. In Phase I, we will synthesize the polymers and use them to encapsulate QDs of defined diameter. Each nanoparticle complex will be characterized in terms of luminescence profile, quantum yield, photostability, and extinction coefficient. These properties will be examined in a variety of environments to determine any pH- or solvent dependent aspects of fluorescence behavior. Both types of encapsulated nanoparticle probes will be used to transfect cultured mammalian cells in order to assess QD luminescence in a physiological milieu.