Exploiting Chemical and Structural Tunability to Harness Temperature-Dependent Luminescence at the Nanoscale

准确和精确地测定温度在诊断和治疗生物系统中是至关重要的。能够作为光学温度传感器的纳米材料非常适合这项任务，因为它们能够在无法实现接触式测温的环境中工作（例如，细胞和深层组织）。然而，绝大多数发光纳米温度计缺乏所需的温度灵敏度。该研究将发现和开发具有温度依赖性发光响应的新型无机纳米材料。通过合成和表征相结合的研究，建立了这些荧光粉的温度敏感性规律。然后使用这些规则来设计在给定温度窗口内具有目标灵敏度的光学温度计。此外，该项目还为本科和研究生水平的劳动力发展以及K-12 STEM外展提供了机会。研究生和本科生在发光纳米材料的合成和高级表征训练。参加由韦恩州立大学主办的年度STEM日的六年级至九年级学生通过基于光刺激荧光粉的实践活动介绍了光学材料的研究。该研究旨在了解如何通过合理匹配宿主和激活剂来调节发光纳米温度计的温度灵敏度。利用一类新型宿主材料的化学和结构可调性来实现这一目的。该工程可分为三个推力区。第一个领域涉及合成一系列无机纳米晶体，这些纳米晶体将二价和三价金属掺杂剂作为发光中心。为此，开发了胶体合成异位和异阴离子纳米晶体的途径。第二个重点是确定发光中心在纳米晶体宿主中的位置。这项任务涉及使用特定元素的光谱探针在多个长度尺度上询问原子排列。最后，在第三个推力中，使用稳态和时间依赖荧光光谱法系统地探测了纳米晶体的温度依赖发光响应。然后推导了组成-结构-发光关系，揭示了控制纳米温度计温度敏感性的基本化学和结构原理。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The accurate and precise determination of temperature is critical in diagnostic and therapeutic biosystems. Nanomaterials capable of serving as optical temperature sensors are uniquely suited for this task because they are able to operate in environments where contact thermometry cannot be implemented (e.g., cells and deep tissues). However, the vast majority of luminescent nanothermometers lack the required temperature sensitivity. New inorganic nanomaterials with temperature-dependent luminescence response will be discovered and developed in this research. Through a combination of synthesis and characterization studies the rules governing the temperature sensitivity of these phosphors are established. These rules are then used to design optical thermometers with targeted sensitivity within a given temperature window. In addition, this project provides opportunities for workforce development at both undergraduate and graduate levels and K-12 STEM outreach. Graduate and undergraduate students are trained in the synthesis and advanced characterization of luminescent nanomaterials. 6th through 9th grade students participating in the annual STEM Day hosted by Wayne State University are introduced to optical materials research through a hands-on activity based on photostimulable phosphors.The research aims to develop an understanding of how to tune the temperature sensitivity of luminescent nanothermometers by rationally matching hosts and activators. The chemical and structural tunability of a novel family of host materials is exploited to this end. The project can be divided into three thrust areas. The first area involves synthesis of a series of inorganic nanocrystals that incorporate divalent and trivalent metal dopants as luminescent centers. To this end, colloidal synthetic routes to heterocationic and heteroanionic nanocrystals are developed. The second thrust focuses on ascertaining the placement of the luminescent centers in the nanocrystalline hosts. This task involves interrogating the atomic arrangement in multiple length scales using element-specific spectroscopic probes. Finally, in the third thrust, the temperature-dependent luminescence response of the nanocrystals is systematically probed using steady-state and time-dependent spectrofluorometry. Composition–structure–luminescence relationships are then derived to reveal the fundamental chemical and structural principles governing the temperature sensitivity of the nanothermometers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.