Lateral Flow Assays Biotesting by Utilizing Plasmonic Nanocrystals Made of Inexpensive Metals – Replacing Gold

Abstract

AbstractDifferent kinds of nanoparticles can be conjugated with diverse biomolecular receptors and employed in biosensing to detect a target analyte (biomarkers of infections, cancer markers, etc.) from biological samples. This proven concept was largely used during the COVID-19 pandemic in over-the-counter gold nanoparticles-based paper strip tests. Considering that gold is expensive and is being largely depleted, here we show that novel and less expensive plasmonic counterparts, titanium nitride (TiN) nanoparticles, and copper nanoparticles covered with a gold shell (Cu@Au) perform comparable or better than gold nanoparticles. After functionalization, these novel nanoparticles provide a high signal, efficiency, and specificity when used on paper strip tests. This allows an easy visual determination of the positive signal and the development of more affordable paper-based test strips. Moreover, by conducting the machine learning study, we have shown that the bio-detection with TiN is more accurate than that with gold, demonstrating the advantage of a broadband plasmonic material. The implementation of lateral flow assays based on TiN and Cu@Au nanoparticles promises a drastic cost reduction of this technology and its widespread applications in tasks of biomedical diagnostics, environmental and food safety, security and doping screening.