Laboratory for Chemistry & Physics of Interfaces, Department of Microsystems Engineering (IMTEK), Albert-Ludwigs-Universität Freiburg, Freiburg 79110, Germany.
Freiburg Institute for Interactive Materials and Bioinspired Technologies (FIT), Albert-Ludwigs-Universität Freiburg, Freiburg 79110, Germany.
ACS Biomater Sci Eng. 2023 Nov 13;9(11):6379-6389. doi: 10.1021/acsbiomaterials.3c00736. Epub 2023 Oct 24.
Paper is an ideal candidate for the development of new disposable diagnostic devices because it is a low-cost material, allows transport of the liquid on the device by capillary action, and is environmentally friendly. Today, colorimetric analysis is most often used as a detection method for rapid tests (test strips or lateral flow devices) but usually gives only qualitative results and is limited by a relatively high detection threshold. Here, we describe studies using fluorescence as a readout tool for paper-based diagnostics. We study how the optical readout is affected by light transmission, scattering, and fluorescence as a function of paper characteristics such as thickness (grammage), water content, autofluorescence, and paper type/composition. We show that paper-based fluorescence analysis allows better optical readout compared to that of nitrocellulose, which is currently the material of choice in colorimetric assays. To reduce the loss of analyte molecules (e.g., proteins) due to adsorption to the paper surface, we coat the paper fibers with a protein-repellent hydrogel. For this purpose, we use hydrophilic copolymers consisting of ,-dimethyl acrylamide and a benzophenone-based cross-linker, which are photochemically transformed into a fiber-attached polymer hydrogel on the paper fiber surfaces in situ. We show that the combination of fluorescence detection and the use of a protein-repellent coating enables sensitive paper-based analysis. Finally, the success of the strategy is demonstrated by using a simple LFD application as an example.
纸张是开发新型一次性诊断设备的理想候选材料，因为它成本低廉，可以通过毛细作用在设备上输送液体，并且对环境友好。如今，比色分析最常用于快速检测（测试条或横向流动装置），但通常只能提供定性结果，并且受到相对较高的检测阈值的限制。在这里，我们描述了使用荧光作为基于纸张的诊断的读出工具的研究。我们研究了光学读出如何随纸张特性（如厚度（克重）、含水量、自发荧光和纸张类型/组成）的变化而受到光传输、散射和荧光的影响。我们表明，与目前比色测定中首选的材料硝酸纤维素相比，基于纸张的荧光分析可以实现更好的光学读出。为了减少由于吸附到纸张表面而导致的分析物分子（例如蛋白质）的损失，我们用抗蛋白水凝胶涂覆纸张纤维。为此，我们使用由 - 二甲基丙烯酰胺和基于二苯甲酮的交联剂组成的亲水性共聚物，它们在纸张纤维表面上通过光化学原位转化为纤维附着的聚合物水凝胶。我们表明，荧光检测与使用抗蛋白涂层的结合能够实现基于纸张的灵敏分析。最后，通过简单的 LFD 应用示例证明了该策略的成功。
