Creating Chirality by Magnetic Assembly of Plasmonic Nanostructures

在化学系大分子、超分子和纳米化学（MSN）项目的支持下，加州大学河滨分校的尹亚东教授正在探索磁场如何驱动纳米颗粒组装成更大的结构，这些结构具有固有的“手性”，类似于许多生物体中看到的左右镜像对称。由于不同的手性结构与光的相互作用不同，这一特性对于解码许多重要生物分子（如核酸和蛋白质）的精细结构非常有用。然而，由于光分子相互作用的细微差异，基于这一特性的传感和检测的实际应用面临着重大挑战。尹教授和他的学生正在开发含有磁性氧化物和贵金属的混合纳米颗粒。磁性成分允许混合纳米粒子在磁场下组装成具有所需手性的更大结构。由此产生的手性可以转移到贵金属组分，表现出实质性的手性相关的光学响应。他们的发现可能会导致更有效的机械和化学传感器以及新型防伪设备的发展。该团队还致力于为加州大学洛杉矶分校、当地学校、社区学院等的K-12和本科生推广基于研究的学习方法。基于对梯度磁场固有手性的理论理解，Yin教授和他的同事正在开发磁性组装策略，以创建新的等离子体手性超结构。磁/等离子体杂化纳米结构在磁场梯度下组装成具有大量波长可控的热效应的超结构。混合纳米球和纳米棒将被用作模型构建块，以探索它们与磁场梯度的相互作用、手性超结构的形成以及由此产生的组装体的场响应性chirotical特性。与此同时，该团队也在探索在均匀磁场中产生手性的方法，方法是利用胶体杂化纳米结构独特的组装行为，以及特殊设计的形状各向异性。将进行系统的研究，以了解纳米颗粒形状如何决定均匀磁场中的组装行为。深入了解这两种体系将有助于进一步探索在磁场梯度下具有特定形状各向异性的纳米结构组装。最终目标是生成具有不同长度尺度的一级手性和二级手性的分层超结构。通过利用这些新型手性材料的场响应性，该团队正在设计具有高灵敏度机械传感器、颜色切换材料甚至防伪设备应用潜力的系统。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。

With support from the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry, Professor Yadong Yin of the University of California – Riverside is exploring how magnetic fields can drive nanoparticles to assemble into larger structures that have an inherent “handedness,” analogous to the left-right mirror symmetry seen in many living organisms. Since structures with different handedness interact with light differently, this property is very useful for decoding the fine structures of many important biomolecules such as nucleic acids and proteins. However, practical applications in sensing and detection based on this property face significant challenges due to subtle differences in light-molecule interactions. Professor Yin and his students are developing hybrid nanoparticles that contain magnetic oxides and noble metals. The magnetic component allows the hybrid nanoparticles to be assembled into larger structures with the desired handedness under a magnetic field. The resulting handedness can be transferred to noble metal components, exhibiting substantial handedness-dependent optical responses. Their discoveries could lead to the development of more effective mechanical and chemical sensors and novel anti-counterfeiting devices. The team is also working on promoting research-based learning approaches for K-12 and undergraduate students at UCR, local schools, community colleges, and beyond.Based on a theoretical understanding of the inherent chirality of gradient magnetic fields, Professor Yin and his co-workers are developing magnetic assembly strategies to create novel plasmonic chiral superstructures. Magnetic/plasmonic hybrid nanostructures are assembled in magnetic field gradients into superstructures with substantial and wavelength-controllable chiroptical responses. Hybrid nanospheres and nanorods will be used as the model building blocks to explore their interactions with magnetic field gradients, the formation of chiral superstructures, and the field-responsive chiroptical properties of the resulting assemblies. In parallel, the team is also exploring the creation of chirality in uniform magnetic fields by taking advantage of the unique assembly behaviors of colloidal hybrid nanostructures with specially designed shape anisotropy. Systematic studies will be carried out to understand how nanoparticle shape can determine assembly behavior in uniform magnetic fields. An in-depth understanding of these two systems would allow for further exploration of nanostructure assembly with specific shape anisotropy in magnetic field gradients. The ultimate goal is to generate hierarchical superstructures featuring primary and secondary chirality of different length scales. By taking advantage of the field-responsive chiroptical properties of these novel chiral materials, the team is designing systems that have the potential for application as highly sensitive mechanical sensors, color-switching materials, and even anti-counterfeiting devices.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.