Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Core Facility Center, National Cheng Kung University, Tainan 701, Taiwan.
Biosensors (Basel). 2022 May 25;12(6):362. doi: 10.3390/bios12060362.
Brownian motion, which is a natural phenomenon, has attracted numerous researchers and received extensive studies over the past decades. The effort contributes to the discovery of optical diffusometry, which is commonly used for micro/nano particle sizing. However, the analysis uncertainty caused by the coupling relationship among particle diameter, temperature, and fluid viscosity usually poses a barrier to precise measurement. Preventing random background noise becomes the key to achieving a high level of accuracy in diffusometry detection. Recently, Janus particles have become known as an ideal tool for resolving the rotational Brownian motion. Followed by our previous study, the rotational Brownian motion and the translational Brownian motion can be separately measured using the Janus particles. Accordingly, a simple self-viscosity and temperature-compensated technique based on the delicate removal of temperature and fluid viscosity variations through particle tracking was first proposed in this study. Consequently, the translational Brownian motion was expressed in terms of particle trajectory, whereas the rotational Brownian motion was expressed in terms of the blinking signal from the Janus particles. The algorithm was verified simulatively and experimentally in temperature (10 °C to 40 °C) and viscosity-controlled (1 mPa·s to 5 mPa·s) fields. In an evaluation of biosensing for a target protein, IFN-γ, the limit of detection of the proposed self-compensated diffusometry reached 0.45 pg/mL, whereas its uncertainties of viscosity and temperature were 96 and 15-fold lower than the pure the rotational Brownian motion counterpart, respectively. The results indicated the low-uncertainty and high-accuracy biosensing capability resulting from the self-viscosity and temperature-compensated technique. This research will provide a potential alternative to future similar bead-based immunosensing, which requires ultra-high stability and sensitivity.
布朗运动是一种自然现象，在过去几十年中吸引了众多研究人员的关注，并进行了广泛的研究。这一努力促成了光扩散度分析的发现，该分析通常用于微/纳米颗粒尺寸测量。然而，由于粒径、温度和流体粘度之间的耦合关系，分析不确定性通常成为精确测量的障碍。防止随机背景噪声成为实现扩散度检测高精度的关键。最近，Janus 粒子已成为解决旋转布朗运动的理想工具。继我们之前的研究之后，使用 Janus 粒子可以分别测量旋转布朗运动和平移布朗运动。因此，本研究首次提出了一种简单的基于粒子跟踪的自粘度和温度补偿技术，通过该技术可以精细地消除温度和流体粘度变化的影响。因此，平移布朗运动可以用粒子轨迹表示，而旋转布朗运动可以用 Janus 粒子的闪烁信号表示。该算法在温度（10°C 至 40°C）和粘度控制（1 mPa·s 至 5 mPa·s）场中进行了模拟和实验验证。在针对目标蛋白 IFN-γ 的生物传感评估中，所提出的自补偿扩散度的检测限达到 0.45 pg/mL，而其粘度和温度的不确定度分别比纯旋转布朗运动对应物低 96 倍和 15 倍。结果表明，自粘度和温度补偿技术具有低不确定度和高精度的生物传感能力。这项研究将为未来类似基于珠粒的免疫传感提供一种潜在的替代方法，该方法需要超高的稳定性和灵敏度。
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