CAREER: Ultrathin Magnetic Ferrite Nanowires for Bioimaging

技术概述：本项目由美国国家科学基金会固态与材料化学（SSMC）项目资助，将研究超薄（直径约4nm）一维磁性纳米线的形成、结构与磁性能的相关性。本文将进一步探讨其作为磁共振成像（MRI）有效造影剂的潜力。在本CAREER提案中，将探索一种新的“选择性加热”方法来合成超薄磁性铁氧体纳米线。这种新方法的关键原理是基于对前体化学的理解，选择性地分解前体复合物的某些配体，为配体定向生长创建配体软模板。铁氧体纳米线独特的尖晶石结构使掺杂成为调整其磁性能的重要参数。因此，在极小尺度下，将系统地研究掺杂对超薄纳米线的形貌、结构和磁性能的影响。最后，对超薄氧化铁和掺杂铁氧体纳米线的弛豫率进行了评价，并进一步与它们的结构和形态进行了关联，建立了合成-结构-性能-弛豫率之间的联系。在MRI中，松弛度是评价造影剂效果的关键参数。所提出的研究将通过揭示合成具有可控结构和磁性能的超薄纳米线的基本知识和设计规则来显著推进该领域的发展。非技术总结：提出的研究将显著推进我们对一种新的湿化学方法合成超薄纳米线的基本理解。所开发的合成策略和潜在的机制可以很容易地扩展到具有类似尺寸的其他纳米材料的制造。除了生物成像，这些超薄磁性铁氧体纳米线在气体传感、光催化、自旋电子学和能源方面具有巨大的潜力。通过一些教育和推广活动，将进一步加强这项职业建议的影响，包括：(1)与当地（石矿场）小学一起发起“儿童科学派对”计划，尽早向学生介绍科学和工程概念；(2)通过研究项目、讲座、科学演示和专业协会，促进代表性不足的群体参与纳米材料；(3)通过多种途径，如同行评议的出版物、研讨会、会议报告、教学、暑期学校讲座和网站，产生和传播由本职业建议产生的新科学知识。

TECHNICAL SUMMARY:This project, supported by the Solid State and Materials Chemistry (SSMC) program at NSF, will investigate the formation, structure-magnetic property correlation of the ultrathin (diameter, d 4 nm), one dimensional magnetic nanowires. It will further explore their potential as effective contrast agents for magnetic resonance imaging (MRI). In this CAREER proposal, a new "selective heating" method for the synthesis of ultrathin magnetic ferrite nanowires will be explored. The key principle to this new approach is to selectively decompose certain ligands of the precursor complex based on an understanding of the precursor chemistry, creating a ligand soft template for ligand-directed growth. The unique spinel structure of ferrite nanowires makes doping an important parameter to tune their magnetic properties. Therefore, doping effects on the morphology, structure, and magnetic property of the ultrathin nanowires at extremely small scale will be systematically investigated. Finally, the relaxivity of ultrathin iron oxide and doped ferrite nanowires will be evaluated and further correlated with their structures and morphologies, establishing a link among synthesis-structure-property-relaxivity. The relaxivity is a key parameter to evaluate the effectiveness of a contrast agent in MRI. The proposed studies will significantly advance the field by unraveling the essential knowledge and design rules for synthesizing ultrathin nanowires with controlled structural and magnetic properties for various applications. NON-TECHNICAL SUMMARY:The proposed studies will significantly advance our fundamental understanding of a new wet chemistry approach to the synthesis of ultrathin nanowires. The developed synthetic strategies and the underlying mechanisms can be readily extended to the fabrication of other nanomaterials with similar dimensions. Beyond bioimaging, these ultrathin magnetic ferrite nanowires have great potential in gas sensing, photocatalysis, spintronics, and energy. The impact of this CAREER proposal will be further enhanced through several educational and outreach activities, including: (1) initiating a "Science Party for Kids" program with a local (Rock Quarry) Elementary School to introduce science and engineering concepts to students early; (2) promoting participation of underrepresented groups in nanomaterials through research programs, lectures, scientific demonstrations, and professional societies; (3) generating and disseminating new scientific knowledge resulting from this CAREER proposal through several avenues, such as peer-reviewed publications, seminars, conference presentations, teaching, summer school lectures, and websites.