Creating Chirality by Magnetic Assembly of Plasmonic Nanostructures

在化学系大分子、超分子和纳米化学(MSN)计划的支持下，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“利手”，类似于许多活着的生物体中看到的左右镜像对称。由于具有不同手性的结构与光的相互作用不同，这一性质对于破译许多重要生物分子的精细结构非常有用，例如核酸和蛋白质。然而，由于光-分子相互作用的细微差异，基于这一性质的传感和检测的实际应用面临着巨大的挑战。殷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。磁性部件允许杂化纳米颗粒在磁场下以所需的利手性组装成更大的结构。由此产生的利手可以转移到贵金属部件上，表现出显著的利手依赖的光学响应。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开发。该团队还致力于为UCR、当地学校、社区大学和其他地方的K-12和本科生推广研究性学习方法。基于对梯度磁场内在手性的理论理解，殷教授和他的同事正在开发磁组装策略，以创造新型的等离子体手性超结构。磁性/等离子混合纳米结构在磁场梯度中组装成具有实质性和波长可控手势响应的超结构。杂化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所得到的组件的场响应手性特性。与此同时，该团队还在探索通过利用具有特殊设计的形状各向异性的胶体杂化纳米结构的独特组装行为，在均匀磁场中创造手性。将进行系统的研究，以了解纳米颗粒的形状如何决定在均匀磁场中的组装行为。对这两个系统的深入了解将允许进一步探索具有特定形状各向异性的磁场梯度的纳米结构组装。最终目标是生成具有不同长度尺度的主手性和次手性的分层超结构。通过利用这些新型手性材料的场响应性手性特性，该团队正在设计具有作为高灵敏度机械传感器、颜色切换材料甚至防伪设备的潜在应用的系统。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.