Colloidal Assembly of Biodegradable Multifunctional Nanoclusters

[968038] johnstonintellectual Merit：纳米技术面临的一个主要挑战是设计出尺寸小于100纳米、具有多种功能的稳定粒子，特别是具有强光学和磁性能的粒子。在表面活性剂的引导下，原子生长的一般方法很难达到所需的粒子形态。因此，一种稳健而灵活的替代方案将被开发出来，以将~ 5nm纳米颗粒构建块物理地组装成多功能纳米团簇。这种胶体动力学和界面组装概念将被开发，以同时获得小于100纳米的尺寸和极高负载（80%）的金和铁氧化物颗粒，以产生强大的光学（近红外吸光度）和磁性（磁矩/体积和自旋-自旋弛度，r2）特性。此外，当可生物降解的聚合物稳定剂被分解时，这些团簇会分解回原始的纳米颗粒，这对于它们在生物医学领域的应用是非常重要的。具体来说，通过调节胶体相互作用来控制团簇的生长、大小和形态，将形成高负载的金和氧化铁纳米颗粒。弱吸附的聚合物稳定剂将有利于更高的无机粒子负载，而不是在平衡自组装的情况下，以及团簇生物降解。对于不同的纳米颗粒组成、表面涂层和稳定聚合物，将通过高分辨率透射电镜和透射电镜断层扫描在不同的倾斜角度下分析簇中每种纳米颗粒的空间取向。近红外表面等离子体共振和自旋-自旋磁弛豫将被测量和解释在团簇形态方面。将用光谱学和动态光散射监测溶液中的团簇脱聚，并用高光谱光学成像和透射电子显微镜监测活细胞中的团簇脱聚。更广泛的影响：这个强大的动力学组装平台，用于设计具有高无机粒子负载的可生物降解纳米团簇，具有强大的多功能特性，将为微电子、传感器、成像和光电子学提供广泛的机会。这种胶体方法形成新型纳米团簇的简单性和灵活性可能会产生大量的实验和理论研究，以了解光学/磁性能和纳米团簇形态之间的关系。此外，光学/磁性纳米颗粒可以为现代医学的主要挑战之一提供解决方案，通过实时成像（光声成像和MRI）进行指导和监测，有效地提供治疗药物和分子特异性病理治疗。纳米团簇的生物降解成初级纳米粒子可以克服纳米技术的主要障碍，即在人体和更广泛的环境中积累时的毒性。一个关键的主题将是向年轻学生展示工程学可以通过整合化学和生物学中的科学概念来解决实际问题，在改善医疗保健方面发挥重要作用。这些pi将开发教育材料、实验室实验，并为全国知名的UTeach外展计划提供学生教师，该计划为奥斯汀独立学区的本科生提供科学课程的志愿教师。在UTeach青年科学家夏令营中，来自西班牙裔小学的六年级学生将来到德克萨斯大学参加为期一周的实践探究性科学课程，这些课程强调学术的严谨性。pi将在科学课程和夏令营中增加工程部分，以补充目前在化学和生物方面的努力。

0968038JohnstonIntellectual Merit:A major challenge in nanotechnology is to design stable particles smaller than 100 nm with multifunctionality, and in particular, strong optical and magnetic properties. It is difficult to achieve the required particle morphology in the common approach of atomic growth guided by surfactants. Thus, a robust and flexible alternative will be developed to assemble ~5 nm nanoparticle building blocks physically into multifunctional nanoclusters. This colloidal kinetic and interfacial assembly concept will be developed to obtain simultaneously sizes below 100 nm and extremely high loadings (80%) of gold and iron oxide particles to produce strong optical (NIR absorbance) and magnetic (magnetic moment/volume and spin-spin relaxivity, r2) properties. In addition, these clusters will disassemble back into the original primary nanoparticles upon breakdown of biodegradable polymer stabilizers, which is very important for their translation to the biomedical field. Specifically, nanoclusters with high loadings of closely paced gold and iron oxide nanoparticles will be formed by tuning the colloidal interactions to control the cluster growth, size, and morphology. Weakly adsorbed polymer stabilizers will favor much higher inorganic particle loadings than in the case of equilibrium self-assembly, as well as cluster biodegradation. The spatial orientation of each type of nanoparticle in the cluster will be analyzed by high resolution TEM and TEM tomography at various tilt angles for a variety of nanoparticle compositions, surface coatings and stablilizing polymers. The NIR surface plasmon resonance and the spin-spin magnetic relaxivity will be measured and explained in terms of the cluster morphology. The cluster de-aggregation will be monitored in solution with spectroscopy and dynamic light scattering and in live cells with hyperspectral optical imaging and transmission electron microscopy. Broader Impact: This robust kinetic assembly platform for the design of biodegradable nanoclusters with high inorganic particle loadings for strong multifunctional properties will offer broad opportunities in microelectronics, sensors, imaging and optoelectronics. The simplicity and flexibility of this colloidal approach to form novel classes of nanoclusters will likely spawn numerous experimental and theoretical studies to understand the relationship between the optical/magnetic properties and nanocluster morphology. Furthermore, the optical/magnetic nanoparticles can provide solutions to one of the major challenges of modern medicine efficient delivery of therapeutics and molecular specific treatment of pathology with real-time imaging (photoacoustic imaging and MRI) for guidance and monitoring. The biodegradation of nanoclusters into primary nanoparticles can overcome the major roadblock in nanotechnology that is toxicity upon accumulation in humans and in the broader environment. A key theme will be to show young students that engineering can play a major role in improving health care, by integrating scientific concepts in chemistry and biology to address practical problems. The PIs will develop educational material, laboratory experiments and provide student teachers for the nationally renowned UTeach Outreach program, which provides undergraduate students to serve as volunteer instructors for science lessons in the Austin Independent School District. In the UTeach Young Scientists Summer Camps, rising sixth grade students from heavily Hispanic elementary Schools will come to University of Texas for one week to participate in hands-on inquiry-based science lessons that stress academic rigor. The PIs will add an engineering component to the science lessons and the summer camp to complement current efforts in chemistry and biology.