Lateral flow assay with green nanomaterials

Paper-based lateral flow assays (LFAs) are currently the most successful point-of-care analytical devices for many applications from hormone detection to pandemic monitoring. During the last decade, the integration of nanomaterials as signal-generating labels has led to improved analytical capabilities in these sensors. Therefore, choosing a suitable LFA label is critical to achieving high efficiency in sensitivity, specificity, and reproducibility. In this chapter, we first describe the basics of LFA technology and methods of signal readout for LFA result quantification. Then we highlight the conventional nanoparticles used in current LFAs and sensitivity enhancement strategies with these nanoparticles such as gold nanoparticles and quantum dots. Finally, different green nanomaterials synthesized by microorganisms and plant extracts that have been recently used as LFA labels are elucidated such as gold and silver nanoparticles, poly phenol tannic acid nanosphere, iron-based nanoparticles, and WS2 nanosheets. Furthermore, the impact of green synthesized NPs in the binding efficiency of antibodies on NPs, the limit of detection (LOD), and cut-off concentration (COC) are given demonstrating that green synthesized NPs have promising prospects to improve the performance and sensitivity of LFA test strips.