Development of Paper-Based Lateral Flow Immunoassay for Detection of Biomarkers in Human Fluids

Rapid and accurate detection of protein and small molecule biomarkers in human blood and saliva are incredibly valuable for clinical applications. However, biomarkers are typically detected using time-consuming and expensive methods such as enzyme-linked immunosorbent assay (ELISA), Western blot, and other centralized laboratory instrumentation, so these tools cannot be used in the point-of-care setting. In this work, a paper-based lateral flow strip (PLFS) has been developed as a rapid, low-cost, point-of-care device for detecting biomarkers in whole blood and saliva. Typically, PLFSs operate using colorimetric detection and suffer from poor sensitivity and high background interference from the biological matrix. To overcome these challenges, surface-enhanced Raman scattering (SERS) and near-infrared fluorescence were applied in a PLFS as the signal transducers to improve device sensitivity and overcome biological interference. These advantages are attributed to the optical excitation in the near-infrared biological transparency window and plasmonic nanostructure enhancement. The PLFS is designed using a plasmonic nanostructures and a blood plasma separation unit for highly sensitive biomarker detection.