Light-Responsive Liquid Metal Particles for Nucleic Acid Extraction and Directional Enrichment

The COVID-19 pandemic revealed key limitations in conventional qPCR diagnostics, including lengthy multi-step nucleic acid extraction and dependence on trained personnel. In this study, photoactive TiO₂@Ga particles are developed capable of rapid viral lysis, nucleic acid extraction, and directional enrichment. Liquid metal gallium (Ga) enhances viral lysis under ultrasound by amplifying acoustic effects and generating reactive oxygen species (ROS) in aqueous environments. TiO₂ provides photocatalytic propulsion under UV irradiation and exhibits high affinity for nucleic acids, enabling efficient capture. Upon UV exposure, protons are generated by water oxidation at TiO₂ and reduced at Ga. The resulting proton flux drives the migration of negatively charged particles toward the TiO₂ side. The particles reached velocities of up to 6 µm s ^-1 under 365 nm UV light at an intensity of 200 mW cm^-2. Under the same conditions, TiO₂@Ga particles exhibited lower qPCR cycle threshold (Ct) values compared with controls, indicating enhanced viral lysis and nucleic acid capture of SARS-CoV-2 plasmids and pseudoviruses. Furthermore, qPCR confirmed efficient extraction and transport of viral nucleic acids within a single-channel microfluidic chip. This integrated, rapid, and user-friendly approach holds strong potential for point-of-care molecular diagnostics.