Lanthanide Containing ZnS Nanoparticles

描述（由申请人提供）：本提案描述了一个通过将硫化锌（ZnS）半导体纳米颗粒与发光镧系离子结合来开发具有先进发光性能的纳米颗粒的计划，从而利用每种纳米颗粒的光物理优势。其目的是利用具有大吸收截面的ZnS纳米颗粒，通过“天线效应”使镧系元素阳离子的发射变得敏感，并提供一种保护镧系元素不受非辐射失活化的基质。ZnS是一种理想的基质，因为它比广泛使用的CdSe纳米晶体毒性更小，但是ZnS的带隙位于紫外/蓝光光谱区域，这使得它们与生物成像应用不相容，因为紫外/蓝色光子与生物系统之间存在强烈的干扰。然而，在ZnS基体中加入镧系离子后，激发能通过镧系离子释放，在可见光和近红外波段形成尖锐的发射带，这是由镧系作用的性质决定的。镧系离子具有清晰的发射带，对其环境（如温度、pH值、压力或生物环境）不敏感，并允许从生物背景（自身荧光）进行光谱区分。镧系离子也有较长的发光寿命（微至毫秒）比许多其他荧光发射器，允许分析物信号和背景荧光之间的时间区分。纳米颗粒表面的化学衍生化将用于为纳米晶体探针提供生化选择性，并使材料安全和可溶，用于目标生物应用。这些材料将在组织和细胞为基础的制剂中进行测试，并与用于荧光显微镜应用的市售探针进行比较。纳米晶体的毒性将在原代细胞培养模型中使用高灵敏度光学成像方法来检测细胞损伤和死亡。

DESCRIPTION (provided by applicant): This proposal describes a program to develop nanoparticles with advanced luminescence properties by combining zinc sulfide (ZnS) semiconductor nanoparticles and luminescent lanthanide cations so that the photophysical advantages of each are exploited. The aim is to use ZnS nanoparticles, with their large absorption cross section, to sensitize the lanthanide cations emission by an "antenna effect" and to provide a matrix that protects the lanthanides from nonradiative deactivation. ZnS is a desirable matrix because it is less toxic than the widely used CdSe nanocrystals, however the ZnS bandgap lies in the ultraviolet/blue spectral region, which has made them incompatible with biological imaging applications because of the strong interference between UV/blue photons and biological systems. However, the addition of lanthanide cations to the ZnS matrix causes the excitation energy to be released through the lanthanide cations as sharp emission bands in the visible and near infrared, determined by the nature of the lanthanide action. The lanthanide cations have sharp well defined emission bands that are insensitive to their environment (such as temperature, pH, pressure or biological environment) and allows for spectral discrimination from biological background (autofluorescence). Lanthanide cations also have longer luminescent lifetimes (micro- to milliseconds) than many other fluorescence emitters, allowing for temporal discrimination between the analyte signal and the background fluorescence. Chemical derivatization of the nanoparticle surface will be used to provide the biochemical selectivity for the nanocrystal probe and to make the material safe and soluble for the targeted biological applications. These materials will be tested in tissue and cell-based preparations and compared to commercially available probes for use in fluorescence microscopy applications. The toxicity of the nanocrystals will be evaluated using highly sensitive optical imaging methodologies for detecting cellular damage and death in primary cell culture models. PUBLIC HEALTH RELEVANCE: We will develop a novel family of luminescent nanoparticles that emit visible or near infrared light and are specifically designed to operate as fluorescent reporters in a broad range of "in vivo" and "in vitro" bioanalytical applications, including biological imaging. Ultimately, these nanoparticles will constitute a versatile luminescence platform whose optical properties will complement existing fluorophores, their signal being easily discriminated from the native fluorescence of biological systems.