低熔点合金纳米粒子的可控制备及其相变的尺寸、形貌和限域效应研究

A combination of nanomaterials and biological detection technologies is a very important research field. Sharp and narrow melting characteristic peaks of nanocrystals allow them to have many advantages in an accurate identification and quantitative detection of biological molecules. This is promsing to breakthrough the limitation of current traditional detection methods that have a low detection sensitivity and cannot detect more than two kinds of biological molecules from a mixed solution simultaneously. However, monodispersed low-melting point alloy particles with diameters smaller than a critical dimension of 20 nm have not yet been gained by reported methods so far, and an easy leakage and agglomeration upon melting has been main obstacles for the experimental study of solid-liquid phase change of nanoparticles and their application in biological detection. In this project, we open a new path starting from these scientific problems, using microwave outfield assistance and restriction role of microcavities, low-melting alloy nanoparticles with diameters below 20 nm will be incorporated into the interior of carbon spheres by fast and selective microwave heating. Developing new mathematical simulation enhanced structure analysis of complex architectures, the problems for efficient quantitative analysis of three-dimensional structures of the composite spheres will be resolved. By using high thermal stability of employed carbon, a systematic study on the solid-liquid phase change behaviors of the particles embeded in carbon will be carried out. One focus will be the investigation of the variation law of critical temperatures in order to reveal the effects of nanparticles' size, shape and carbon's confinement on the phase change behaviors of the alloy nanoparticles. We will optimize materials' performances including detection sensitivity and selectivity accroding to the solid-liquid phase change characteristics of samll particles.The study will establish a theoretical and experimental basis for practical applications of these spherical nanoalloys-carbon composites in biomedical science.

纳米材料与生物检测技术相结合是当今纳米科技的重要研究领域。纳米晶体因具有尖锐且窄的熔化峰在生物分子识别和定量分析方面具有独特优势，有望突破传统方法灵敏度低、多种分子无法同时检测的局限。然而，现有技术尚无法获得单分散、小于临界尺寸（20nm）的低熔点合金纳米粒子，且熔化时易流动和团聚已成为固液相变实验研究及其生物检测应用的主要障碍。本项目另辟蹊径，以外场辅助、微孔限制为技术导向，借助微波选择性、快速加热和碳孔道的空间约束作用，实现小尺寸低熔点合金纳米粒子的制备及其在球形碳内部的高度均匀分散；发展数学模拟辅助图像分析的新方法，解决合金粒子的三维分布、结构特征等定量表征的难题；利用碳的热稳定性，从实验上对粒子的固液相变特性进行系统研究，着重探讨相变的递变规律，揭示尺寸、形貌和限域效应的物理机制；以小尺寸粒子相变特性为基础优化生物分子检测性能，为其在生物医学中的实际应用奠定理论和实验基础。

纳米材料与生物检测技术相结合是当今纳米科技的重要研究领域。纳米粒子的固-液相变已被广泛关注，纳米晶体因具有尖锐且窄的熔化峰在生物分子识别和定量分析方面具有独特优势，有望突破传统方法灵敏度低、多种分子无法同时检测的局限。由于小尺寸低熔点合金材料的可控制备和相变分析发展的滞后，研究主要集中在理论模拟方面，实验研究涉及甚少，许多结论亟待实验证实。纳米粒子熔化时易流动和团聚已成为实验研究及其生物检测应用的主要障碍。现有制备方法获得的粒子尺寸都大于相变临界尺寸，熔化温度和体材相同，尚无法获得单分散、小于临界尺寸（20nm）的低熔点合金纳米粒子；针对粒子在复合结构中的三维分布、数密度和含量等的定量分析，传统表征技术已无法完成。.针对以上科学问题，项目组结合微波加热高选择性及碳限域生长动力学，提出了以外场辅助、微孔限制为技术导向，借助微波选择性、快速加热和碳孔道的空间约束作用，实现小尺寸低熔点合金纳米粒子的制备及其在球形碳内部的高度均匀分散等新方案，并开展了系统的研究，已取得了一系列原创性成果。主要包括：1）制备了不同形貌低熔点金属Bi、In和合金Bi-Sn纳米粒子，深入探讨了尺寸、形貌和碳微孔限域作用对低熔点合金纳米粒子相变行为的影响；2）实现了球形碳包埋由相连纳米粒子构成三维枝状结构的可控制备；3）改进了三维复合结构表征的新技术，对纳米粒子在多孔微米球形碳载体内空间分布进行了理论模拟；4）通过控制原子摩尔比，实现了多元金属网状纳米结构的优化，获得单层不连续粒子包覆球形颗粒构成的网状结构材料，并研究了界面、组分协同效应对生物分子定量检测的影响。5）在此基础上，项目组进一步实现了生物单分子的高精度、高重复性检测。项目组不仅达到了研究目标，而且进一步实现了新型的三维多孔金属纳米结构的设计与制备，该材料表现出了很高的检测灵敏度，对R6G分子的检测可达10-16M，明显优于国际上报道的数值。