Murph Simona E Hunyadi, Larsen George K, Lascola Robert J
National Security Directorate, Savannah River National Laboratory;
National Security Directorate, Savannah River National Laboratory.
J Vis Exp. 2016 Feb 20(108):53598. doi: 10.3791/53598.
One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.
制造胶体金纳米球颗粒最广泛使用的方法之一是通过还原剂（如柠檬酸钠或硼氢化钠）将氯金酸（HAuCl4）还原为中性金Au(0)。将该方法扩展到用金纳米颗粒修饰氧化铁或类似的纳米颗粒以制备多功能杂化Fe2O3-Au纳米颗粒很简单。这种方法能较好地控制金纳米颗粒的尺寸以及其在Fe2O3上的负载量。此外，通过改变实验参数（如反应物浓度、还原剂、表面活性剂等），可以轻松调节金金属的尺寸、形状和负载量。该方法的一个优点是反应可以在空气或水中进行，原则上适合扩大规模。将这种光学可调谐的Fe2O3-Au纳米颗粒用于热疗研究是一个有吸引力的选择，因为它利用了金纳米颗粒的等离子体加热效应，使其在可见光-近红外区域强烈吸收光。除了其等离子体效应外，纳米级金还为有趣的化学和催化提供了独特的表面。Fe2O3材料因其磁性提供了额外的功能。例如，在催化实验后，可以使用外部磁场收集和回收杂化Fe2O3-Au纳米颗粒，或者，磁性Fe2O3可通过磁热感应用于热疗研究。本报告中描述的光热实验分别使用红外热电偶和天平测量了作为时间函数的整体温度变化和纳米颗粒溶液质量损失。样品制备简单且使用现成的设备是该技术的明显优势。需要注意的是，这些光热测量评估的是整体溶液温度，而不是纳米颗粒表面的温度，热量在纳米颗粒表面传导，那里的温度可能更高。
