基于金-银纳米异质二聚体的双酚A的表面增强拉曼光谱检测方法

构建了一种基于金-银纳米异质二聚体的表面增强拉曼光谱（SERS）检测新方法,实现对双酚A（BPA）的快速、高灵敏传感检测。以DNA分子为模板定向制备高产率的、内嵌有BPA核酸适配体序列的金-银纳米异质二聚体,利用二聚体对其表面拉曼活性分子的增强作用,从而获得强烈的SERS信号。当体系中存在BPA时,会与金纳米颗粒表面修饰的核酸适配体特异性识别,使得金-银异质二聚体解离,体系的SERS信号减弱。利用BPA的浓度与SERS信号强度的变化关系建立标准曲线,达到快速定量检测的目的。结果表明：构建的SERS方法可在30min内实现BPA的高灵敏、高特异性检测。在优化条件下,方法线性范围为0.05-10μg/L,检测限为0.038μg/L。通过实际样品的加入回收实验,证明该方法具有很好的实际应用价值。

不均匀环境中二聚体微纳米马达的动力学性质

主要研究燃料不均匀环境中的二聚体微纳米马达的动力学性质。采用混合的分子动力学和多粒子碰撞动力学(Molecular Dynamics-Multi-Particle Collision Dynamics,MD-MPC)方法进行系统建模,并通过计算机模拟仿真二聚体微纳米马达在不均匀环境中的自驱动和群集现象。研究表明,在燃料富集区域,微纳米马达展现自驱动行为,显示较高的活性运动。并且,在速度较高的区域,不同于其他类型的马达,化学能驱动的微纳米马达反而呈群集现象,使得马达群体在不均匀环境中表现出有趣的相分离现象,即高速运动燃料区的团簇集群和非燃料区呈分散状态。

Finding Critical Nuclei in Phase Transformations by Shrinking Dimer Dynamics and its Variants

We investigate the critical nuclei morphology in phase transformation by combining two effective ingredients,with the first being the phase field modeling of the relevant energetics which has been a popular approach for phase transitions and the second being shrinking dimer dynamics and its variants for computing saddle points and transition states.In particular,the newly formulated generalized shrinking dimer dynamics is proposed by adopting the Cahn-Hilliard dynamics for the generalized gradient system.As illustrations,a couple of typical cases are considered,including a generic system modeling heterogeneous nucleation and a specific material system modeling the precipitate nucleation in FeCr alloys.While the standard shrinking dimer dynamics can be applied to study the non-conserved case of generic heterogeneous nucleation directly,the generalized shrinking dimer dynamics is efficient to compute precipitate nucleation in FeCr alloys due to the conservation of concentration.Numerical simulations are provided to demonstrate both the complex morphology associated with nucleation events and the effectiveness of generalized shrinking dimer dynamics based on phase field models.

金-银纳米棒异质二聚体的Fano共振及其传感性质研究

本文我们通过有限时域差分法模拟研究了金-银纳米棒异质二聚体的光学等离子体耦合。在消光谱中,发现较短的银纳米棒产生的偶极明模式和较长的金纳米棒产生的四极暗模式产生了干涉相消耦合,从而出现了Fano共振。通过改变金属纳米棒的长度、距离和周围环境可以调控Fano共振的共振波长和强度。金-银纳米棒异质二聚体对周围环境变化具有较高的灵敏度,其品质因数大于8.5。由于金银异质体有比较好的抗腐蚀性和比较低的生物毒性,这使得它有望成为新一代基于表面等离子体Fano共振的生物传感器和分子探测器。