Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Melbourne, VIC 3050, Australia.
Department of Neuroscience, The Alfred Centre, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia.
Biosensors (Basel). 2022 Feb 10;12(2):108. doi: 10.3390/bios12020108.
The magnetic beads detection-based immunoassay, also called magneto-immunoassay, has potential applications in point-of-care testing (POCT) due to its unique advantage of minimal background interference from the biological sample and associated reagents. While magnetic field detection technologies are well established for numerous applications in the military, as well as in geology, archaeology, mining, spacecraft, and mobile phones, adaptation into magneto-immunoassay is yet to be explored. The magnetic field biosensors under development tend to be multilayered and require an expensive fabrication process. A low-cost and affordable biosensing platform is required for an effective point-of-care diagnosis in a resource-limited environment. Therefore, we evaluated a single-layered magnetic biosensor in this study to overcome this limitation. The shape-induced magnetic anisotropy-based planar hall effect sensor was recently developed to detect a low-level magnetic field, but was not explored for medical application. In this study, the elliptical-shaped planar hall effect (EPHE) sensor was designed, fabricated, characterized, and optimized for the magneto-immunoassay, specifically. Nine sensor variants were designed and fabricated. A customized measurement setup incorporating a lock-in amplifier was used to quantify 4.5 µm magnetic beads in a droplet. The result indicated that the single-domain behaviour of the magnetic film and larger sensing area with a thinner magnetic film had the highest sensitivity. The developed sensor was tested with a range of magnetic bead concentrations, demonstrating a limit of detection of 200 beads/μL. The sensor performance encourages employing magneto-immunoassay towards developing a low-cost POCT device in the future.
基于磁珠检测的免疫分析，也称为磁免疫分析，由于其从生物样本和相关试剂中最小化背景干扰的独特优势，在即时检测（POCT）中有潜在的应用。尽管磁场检测技术在军事、地质、考古、采矿、航天和移动电话等众多领域的应用已经得到很好的确立，但将其应用于磁免疫分析仍有待探索。正在开发的磁场生物传感器往往是多层的，需要昂贵的制造工艺。在资源有限的环境中进行有效的即时诊断，需要一个低成本和负担得起的生物传感平台。因此，我们在这项研究中评估了单层磁生物传感器，以克服这一限制。基于形状诱导磁各向异性的平面霍尔效应传感器最近被开发出来用于检测低水平磁场，但尚未探索其在医学应用中的应用。在这项研究中，专门设计、制造、表征和优化了椭圆形平面霍尔效应（EPHE）传感器用于磁免疫分析。设计并制造了九个传感器变体。使用包含锁相放大器的定制测量装置来定量检测液滴中的 4.5 µm 磁珠。结果表明，磁膜的单畴行为和具有更薄磁膜的更大感测面积具有最高的灵敏度。开发的传感器经过一系列磁珠浓度测试，显示出 200 个磁珠/μL 的检测限。传感器的性能鼓励将来采用磁免疫分析来开发低成本的 POCT 设备。
