Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011, United States.
Department of Chemical and Biomolecule Engineering, Iowa State University, Ames, IA 50011, United States.
Biosens Bioelectron. 2019 Mar 1;128:91-96. doi: 10.1016/j.bios.2018.12.031. Epub 2018 Dec 24.
This paper demonstrates the use of a smartphone-based sensor for fluorescence polarization (FP) analysis of biomolecules. The FP detection can rapidly sense ligand-analyte bindings by measuring molecule mobility, and thus, FP-based assays have been widely used for rapid diagnostics in clinics. Here, we implemented the FP detection apparatus using a 3D-printed compact holder and the built-in camera of a smartphone. The system offers accurate measurements of the degree of polarization by simultaneously detecting the fluorescence intensities parallel and perpendicular to the polarization of the excitation. The fluorescence signal of the sample is excited by a laser or light-emitting diode and separated by a polarization beam cube depending on the polarization. Parallel and perpendicular polarized emissions are projected onto two different regions of the sensor chip in the smartphone camera. A custom software app was developed to count the average intensity in the areas of interest and compute the degree of polarization. We validated the system by measuring the polarization of dye molecules dissolved in solutions with different viscosities. As an example of biomolecule sensing, a competitive FP immunoassay of Prostaglandin E was demonstrated using the developed system and exhibited the limit of detection of 1.57 ng/mL. The smartphone-based FP assay platform can also be implemented for the detection of toxins, disease biomarkers, and pathogens in resource-limited settings.
本文展示了一种基于智能手机的传感器在荧光偏振（FP）分析生物分子中的应用。FP 检测可以通过测量分子的流动性来快速感知配体-分析物的结合，因此，基于 FP 的分析已广泛应用于临床的快速诊断。在这里，我们使用 3D 打印的紧凑支架和智能手机的内置摄像头来实现 FP 检测装置。该系统通过同时检测与激发偏振平行和垂直的荧光强度，提供了对偏振度的精确测量。样品的荧光信号由激光或发光二极管激发，并根据偏振通过偏振光束立方体分离。平行和垂直偏振的发射被投射到智能手机相机中传感器芯片的两个不同区域。开发了一个自定义软件应用程序来计算感兴趣区域的平均强度并计算偏振度。我们通过测量溶解在不同粘度溶液中的染料分子的偏振来验证该系统。作为生物分子传感的一个例子，使用所开发的系统展示了前列腺素 E 的竞争性 FP 免疫分析，其检测限为 1.57ng/mL。基于智能手机的 FP 分析平台也可用于在资源有限的环境中检测毒素、疾病生物标志物和病原体。
