CAREER: Engineering Bimetallic Nanostructures as Peroxidase Mimics for Diagnostic Applications

化学家在传感器设计中经常采用的一种策略是使用一种称为“催化剂”的化学物质，这种物质可以引起化学变化。在本项目中，期望的变化是从无色化学品形成有色产品用于检测目的。 然后可以通过比色测定来检测目标化学品的存在，该比色测定量化有色产物的强度。 虽然比色技术很容易使用，无需长时间的培训，并与廉价的设备，比色测定的检测灵敏度可能低于最佳。在这个由化学系的高分子、超分子和纳米化学项目资助的项目中，密歇根理工大学的Xiaohu Xia教授正在研究纳米结构作为化学传感器的活性成分，以获得其非常小的颗粒尺寸和化学成分所产生的特性。 它们的行为模仿天然存在的过氧化物酶，过氧化物酶是一种善于将生物疾病标志物转化为有色产物但反应性低的酶。 研究的合成和基本的催化行为的纳米粒子的评价，通过它们的使用在灵敏和可靠的比色测定疾病的生物标志物。这项研究的更广泛影响来自于创建简单且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。 在教育和外联活动方面也产生了更广泛的影响，这些活动使研究生和本科生，特别是妇女和少数民族，参与基础研究。 这项研究被纳入密歇根州上半岛K-12学生的外展活动。 纳米晶体结构清晰，形状独特，大小均匀，是一个生动的例子，特别适合K-12年级的学生，以培养他们对现代纳米科学和纳米技术的兴趣和好奇心。在这个由化学系大分子，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，因为它们能够充当针对目标疾病标记物的过氧化物酶模拟物分子。 该研究设计了独特的Pd@M_nL核@壳结构中的Pd纳米颗粒，其中M由Pt，Ir，Rh，Ru或Au组成，纳米层数（nL）等于1-10个原子层。 通过仔细控制表面的晶面和元素组成，夏博士能够最大限度地提高纳米颗粒的效率，以提高比色测定中的检测限。 通过将原子级电子显微镜成像与理论模拟相结合，本研究解决了目前仅知之甚少的纳米颗粒过氧化物酶模拟物的结构-性质关系的科学问题。 改进的传感器技术对研究产生了更广泛的影响，因为作为天然过氧化物酶的替代品，这些高效的模拟物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参与基础研究。 这项研究被纳入密歇根州上半岛K-12学生的外展活动。 这些定义明确的纳米晶体具有引人注目的形状和均匀的尺寸，是特别适合K-12级学生的生动例子，以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.