Department of Chemistry, Vanderbilt University, Nashville, TN, USA.
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA.
Anal Methods. 2021 May 13;13(18):2137-2146. doi: 10.1039/d1ay00236h.
Lateral flow assays (LFAs) are immunochromatographic point-of-care devices that have greatly impacted disease diagnosis through their rapid, inexpensive, and easy-to-use form factor. While LFAs have been successful as field-deployable tools, they have a relatively poor limit of detection when compared to more complex methods. Moreover, most design and manufacturing optimization is achieved through time- and resource-intensive brute-force optimization. Despite increased interests in LFA manufacturing, more quantitative tools are needed to study current manufacturing protocols and therefore, optimize and streamline development of these devices further. In this work, we focus on a critical LFA component, colloidal gold conjugated to a detection antibody, one of the most commonly used reporter elements. This study utilizes inductively coupled plasma optical emission spectroscopy (ICP-OES) in conjunction with a lateral flow reader to quantitatively analyze colloidal gold distributions at the read-out test and control lines, as well as residual gold on the conjugate pad and other flow through regions. Our goals are to develop a more rigorous understanding of current LFA designs as well as a quantitative understanding of shortcomings of operational characteristics for future improvement. To our knowledge, this is the first time that ICP-OES has been used to study the initial distribution of colloidal gold on an unused LFA and its redistribution after a test is performed. Using three different brands of commercially available malaria LFAs, gold content was measured within each section of an LFA at varying parasite test concentrations. As expected, the total mass of gold remained unchanged after LFA use; however, the total mass of initial gold and its redistribution varied among manufacturers. Importantly, there are also some inherent inefficiencies that exist in these commercial LFA designs; for example, only 30% of the total gold deposited onto Brand A LFAs binds to the test and control lines, sections of the test that contain interpretable signal. Using information gathered with this method, future devices could be more purposefully engineered to focus on improved binding efficiency, resulting in reduced costs, improved limit of detection, and diminished test-to-test and manufacturer-to-manufacturer variability.
侧向流动分析（LFA）是免疫层析即时检测设备，由于其快速、廉价和易于使用的特点，极大地推动了疾病诊断技术的发展。尽管 LFA 作为现场部署工具取得了成功，但与更复杂的方法相比，其检测限相对较差。此外，大多数设计和制造优化都是通过耗时且资源密集型的盲目优化来实现的。尽管人们对 LFA 制造越来越感兴趣，但需要更多的定量工具来研究当前的制造协议，从而进一步优化和简化这些设备的开发。在这项工作中，我们专注于侧向流动分析中的一个关键组件，即与检测抗体结合的胶体金，这是最常用的报告元素之一。本研究利用电感耦合等离子体发射光谱（ICP-OES）与侧向流动阅读器相结合，定量分析了读取测试线和控制线处胶体金的分布，以及在结合垫和其他流动通过区域的残留金。我们的目标是更深入地了解当前的 LFA 设计，并深入了解操作特性的不足之处，以便未来进行改进。据我们所知，这是首次使用 ICP-OES 来研究未使用的 LFA 上胶体金的初始分布及其在测试后重新分配的情况。使用三种不同品牌的商业疟疾 LFA，在不同的寄生虫测试浓度下测量 LFA 每个部分的金含量。正如预期的那样，LFA 使用后金的总质量保持不变；然而，初始金的总质量及其在制造商之间的重新分配情况有所不同。重要的是，这些商业 LFA 设计中还存在一些固有的效率低下问题；例如，只有 30%沉积在 A 品牌 LFA 上的总金与测试和控制线结合，而测试线和控制线包含可解释的信号。使用这种方法收集的信息，未来的设备可以更有针对性地设计，以提高结合效率为重点，从而降低成本、提高检测限，并减少测试间和制造商间的变异性。
