Department of Physics & IUTA, University of Oviedo, Campus de Viesques, 33204 Gijón, Spain.
Analyst. 2020 Aug 24;145(17):5905-5914. doi: 10.1039/d0an00849d.
Lateral flow assays may be used by minimally trained personnel for fast and inexpensive bioanalyses in decentralized non-exigent environments. Their extension to a broader catalog of applications depends on improvements in their quantification and their sensitivity. We report a strategy that combines nanomagnetic tagging of the analyte of interest with radiofrequency inductive sensing, easy to achieve in friendly and portable format. To optimize nanotag performance, we investigated the influences of their magnetic core size and agglomeration. Iron oxide nanoparticles, with sizes from 5 to 23 nm, were synthesized by thermal decomposition and then coated with dimercaptosuccinic acid and functionalized with neutravidin protein. We tested the system by immobilizing biotin in lateral flow membrane strips. When a sample containing the particles flows along the membrane, the biotin captures the neutravidin together with the magnetic nanotags, which are detected by the inductive sensor. The optimal nanotag core size is the critical threshold for superparamagnetic behavior, which maximizes both the initial magnetic permeability and the saturation magnetization. Controlled agglomeration of the nanotags increases the magnetic mass captured in the test line and further amplifies the signal.
侧流分析可以由经过最少训练的人员在分散的非紧急环境中快速、廉价地进行生物分析。它们在更广泛的应用目录中的扩展取决于它们的定量和灵敏度的提高。我们报告了一种策略，该策略将感兴趣的分析物的纳米磁标记与射频感应相结合，易于以友好和便携式的格式实现。为了优化纳米标记的性能，我们研究了它们的磁芯尺寸和聚集的影响。通过热分解合成了尺寸为 5 至 23nm 的氧化铁纳米颗粒，然后用二巯基丁二酸进行涂层，并通过亲和素蛋白进行功能化。我们通过将生物素固定在侧流膜条上测试了该系统。当含有颗粒的样品沿膜流动时，生物素与亲和素一起捕获纳米磁珠，而这些磁珠则由感应传感器检测。最佳的纳米磁芯尺寸是超顺磁行为的临界阈值，它使初始磁导率和饱和磁化强度最大化。纳米磁珠的受控聚集增加了测试线中捕获的磁性质量，并进一步放大了信号。
