Shi Yipeng, Khurshid Hafsa, Ness Dylan B, Weaver John B
Department of Physics, Dartmouth College, Hanover, NH 03755, United States of America.
Phys Med Biol. 2017 Oct 4;62(20):8102-8115. doi: 10.1088/1361-6560/aa8a4a.
A series of techniques have been developed to use magnetic nanoparticles as biosensors to characterize their local microenvironment. Two approaches have been used to obtain quantitative information: model based approaches and scaling based approaches. We have favored scaling based approaches, because approximations made in models can lead to limitations in the accuracy. Currently all the scaling approaches use harmonic ratios to retrieve physical parameters like temperature, viscosity and relaxation time. In this work, we showed that the phase angle of the signal at a single harmonic frequency is an alternative to the ratio. The phase angle is nanoparticle density-independent, and can be used to improve sensitivity, enabling us to measure smaller biomedical effects. With the phase angle as an example, we showed that scaling methods are general and do not depend on specific approximations. We showed that the same scaling techniques can be used with both the phase angle and harmonic ratio because they both depend on the same combinations of physical parameters. Using the phase angle improves the precision and using the combination of phase angles and harmonic ratio provides the best precision.
已经开发出一系列技术，利用磁性纳米颗粒作为生物传感器来表征其局部微环境。有两种方法可用于获取定量信息：基于模型的方法和基于标度的方法。我们更倾向于基于标度的方法，因为模型中所做的近似可能会导致精度受限。目前所有的标度方法都使用谐波比来获取诸如温度、粘度和弛豫时间等物理参数。在这项工作中，我们表明在单个谐波频率下信号的相角是谐波比的一种替代方法。相角与纳米颗粒密度无关，可用于提高灵敏度，使我们能够测量更小的生物医学效应。以相角为例，我们表明标度方法具有通用性，不依赖于特定的近似。我们表明相同的标度技术可用于相角和谐波比两者，因为它们都依赖于相同的物理参数组合。使用相角可提高精度，而将相角与谐波比结合使用可提供最佳精度。
