CAREER: Engineering Bimetallic Nanostructures as Peroxidase Mimics for Diagnostic Applications

化学家在设计传感器时经常采用的一种策略是使用一种叫做“催化剂”的化学物质，这种物质可以引起化学变化。在目前的项目中，期望的变化是从检测目的的有色化学品中形成有色产品。目标化学物质的存在可以通过比色法检测，该比色法量化了有色产物的强度。虽然比色技术易于使用，无需长时间的培训和廉价的设备，但比色分析的检测灵敏度可能低于最佳值。在这个由化学学部大分子、超分子和纳米化学项目资助的项目中，密歇根理工大学的夏晓虎教授正在研究双金属纳米结构作为化学传感器的活性成分，其特性源于其非常小的粒径和化学成分。它们的行为与自然产生的过氧化物酶类似，过氧化物酶是一种善于将生物疾病标志物转化为彩色产物的酶，但其反应性较低。双金属纳米颗粒的合成和基本催化行为的研究是通过它们在疾病生物标志物的灵敏和可靠的比色测定中使用来评估的。研究结果的更广泛影响来自于创造简单和负担得起的传感器技术，这些技术可以通过更好的疾病生物标志物检测大大提高我们的生活水平。教育和外联活动也产生了更广泛的影响，使研究生和本科生，特别是妇女和少数民族学生参与基础研究。这项研究被整合到密歇根州上半岛的K-12学生的外展活动中。定义明确的纳米晶体，具有醒目的形状和均匀的大小，作为生动的例子，特别适合K-12水平的学生培养他们对现代纳米科学和纳米技术的兴趣和好奇心。在这个由化学学部大分子、超分子和纳米化学项目资助的项目中，密歇根理工大学的夏晓虎教授正在研究双金属纳米结构作为化学传感器的活性成分，因为它们能够作为过氧化物酶模拟物来靶向疾病标记分子。研究工程师将双金属纳米颗粒制成独特的Pd@M_nL core@shell结构，其中M由Pt， Ir, Rh， Ru或Au组成，纳米层（nL）的数量等于1-10原子层。通过仔细控制晶体平面和表面元素组成，夏博士能够最大限度地提高双金属颗粒的效率，以提高比色分析的检测限。通过将原子级电子显微镜成像与理论模拟相结合，本研究解决了双金属纳米颗粒过氧化物酶模拟物的结构-性质关系的科学问题，这些问题目前知之甚少。研究结果的更广泛影响来自改进的传感器技术，因为作为天然过氧化物酶的替代品，这些高效的模拟物可直接用于疾病生物标志物的体外诊断。在教育和外联活动方面也产生了更广泛的影响，这有利于研究生和本科生，特别是妇女和少数民族学生参与基础研究。这项研究被整合到密歇根州上半岛的K-12学生的外展活动中。定义明确的纳米晶体，具有醒目的形状和均匀的大小，作为生动的例子，特别适合K-12水平的学生培养他们对现代纳米科学和纳米技术的兴趣和好奇心。

A strategy chemists often employ in sensor design is to use a chemical called a "catalyst", a substance that can bring about a chemical change. In the present project the desired change is the formation of colored products from uncolored chemicals for detection purposes. The presence of the targeted chemical can then be detected by colorimetric assay which quantifies the intensity of the colored product. While colorimetric technology is easy to use without lengthy training and with inexpensive equipment, the detection sensitivity of colorimetric assays can be less than optimum. In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Professor Xiaohu Xia of Michigan Technological University is studying bimetallic nanostructures as the active component of chemical sensors for properties that result from their very small particle size and their chemical composition. Their behavior mimics that of naturally-occurring peroxidases, a type of enzyme that is good at transforming biological disease markers into colored products but which suffers from low reactivity. Investigation of the synthesis and fundamental catalytic behavior of the bimetallic nanoparticles are evaluated by their use in sensitive and reliable colorimetric assays for disease biomarkers. Broader impacts of the research result from the creation of simple and affordable sensor technologies which can greatly improve our standard of living through better disease biomarker detection. Broader impacts are also made in education and outreach activities, which engage graduate and undergraduate students, especially women and minorities, in fundamental research. The research is integrated into outreach activities for K-12 students from the Upper Peninsula of Michigan. The well-defined nanocrystals, with striking shapes and uniform sizes, serve as vivid examples that are particularly appropriate for the K-12 level students to foster their interests and curiosities in modern nanoscience and nanotechnology.In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Professor Xiaohu Xia of Michigan Technological University is studying bimetallic nanostructures as the active component of chemical sensors for their ability to act as peroxidase mimics toward targeted disease marker molecules. The research engineers the bimetallic nanoparticles in a unique Pd@M_nL core@shell structure, where M is composed of Pt, Ir, Rh, Ru, or Au and with the number of nanolayers (nL) equal to 1-10 atomic layers. By carefully controlling the crystallographic plane and elemental composition of the surface, Dr. Xia is able to maximize the efficiency of the bimetallic particles for improved detection limits in colorimetric assays. By coupling atomic-level electron microscopy imaging with theoretical simulations, this research addresses scientific questions of the structure-property relationships of bimetallic nanoparticle peroxidase mimics that are presently only poorly understood. Broader impacts of the research result from improved sensor technology, since as alternatives to natural peroxidase, these highly efficient mimics are straightforwardly to use for in-vitro diagnostics of disease biomarkers. Broader impacts are also made in education and outreach activities, which benefit in the engagement of graduate and undergraduate students, especially women and minorities, in fundamental research. The research is integrated into outreach activities for K-12 students from the Upper Peninsula of Michigan. The well-defined nanocrystals, with striking shapes and uniform sizes, serve as vivid examples that are particularly appropriate for the K-12 level students to foster their interests and curiosities in modern nanoscience and nanotechnology.