Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen 518172, China.
Biosensors (Basel). 2021 Nov 25;11(12):474. doi: 10.3390/bios11120474.
Over the past decades, paper-based lateral flow immunoassays (LFIAs) have been extensively developed for rapid, facile, and low-cost detection of a wide array of target analytes in a point-of-care manner. Conventional home pregnancy tests are the most significant example of LFAs, which detect elevated concentrations of human chorionic gonadotrophin (hCG) in body fluids to identify early pregnancy. In this work, we have upgraded these platforms to a higher version by developing a customized microfluidic paper-based analytical device (μPAD), as the new generation of paper-based point-of-care platforms, for colorimetric immunosensing. This will offer a cost-efficient and environmentally friendly alternative platform for paper-based immunosensing, eliminating the need for nitrocellulose (NC) membrane as the substrate material. The performance of the developed platform is demonstrated by detection of hCG (as a model case) in urine samples and subsequently indicating positive or negative pregnancy. A dual-functional silane-based composite was used to treat filter paper in order to enhance the colorimetric signal intensity in the detection zones of μPADs. In addition, microfluidic pathways were designed in a manner to provide the desired regulated fluid flow, generating sufficient incubation time (delays) at the designated detection zones, and consequently enhancing the obtained signal intensity. The presented approaches allow to overcome the existing limitations of μPADs in immunosensing and will broaden their applicability to a wider range of assays. Although, the application of the developed hCG μPAD assay is mainly in qualitative (i.e., positive or negative) detection of pregnancy, the semi-quantitative measurement of hCG was also investigated, indicating the viability of this assay for sensitive detection of the target hCG analyte within the related physiological range (i.e., 10-500 ng/mL) with a LOD value down to 10 ng/mL.
在过去的几十年中，基于纸的侧向流动免疫分析（LFIAs）已经得到了广泛的发展，用于快速、简便和低成本地检测各种目标分析物，尤其适用于即时检测。传统的家庭妊娠测试是 LFIAs 的最显著示例，它可以检测体液中人绒毛膜促性腺激素（hCG）的浓度升高，以确定早期妊娠。在这项工作中，我们通过开发定制的微流控纸基分析器件（μPAD）将这些平台升级到了更高版本，μPAD 作为新一代基于纸的即时检测平台，用于比色免疫传感。这将为基于纸的免疫传感提供一种具有成本效益和环保的替代平台，消除了对硝酸纤维素（NC）膜作为基底材料的需求。通过在尿液样本中检测 hCG（作为模型案例）并随后指示妊娠阳性或阴性，来证明所开发平台的性能。使用双功能硅烷基复合材料处理滤纸，以增强 μPAD 检测区的比色信号强度。此外，以提供所需的受控流体流动的方式设计微流道，在指定的检测区产生足够的孵育时间（延迟），从而增强获得的信号强度。所提出的方法可以克服 μPAD 在免疫传感中的现有局限性，并拓宽其在更广泛的分析物检测中的应用。尽管开发的 hCG μPAD 检测方法主要用于妊娠的定性（即阳性或阴性）检测，但也研究了 hCG 的半定量测量，表明该检测方法具有用于在相关生理范围内（即 10-500ng/mL）对目标 hCG 分析物进行灵敏检测的可行性，检测下限（LOD）低至 10ng/mL。
