Surface acoustic wave-driven enhancement of enzyme-linked immunosorbent assays: ELISAW

Enzyme-linked immunosorbent assays (ELISAs) are widely used in biology and clinical diagnosis. Relying on antigen–antibody interaction through diffusion, the standard ELISA protocol can be time-consuming, preventing its use in rapid diagnostics. We present a time-saving and more sensitive ELISA without changing the standard setup and protocol, using surface acoustic waves (SAWs) to enhance performance. Each step of the assay is improved principally via acoustic streaming-driven advection. Using SAWs, the time required for one step of an example ELISA is reduced from 60 to 15 min to achieve the same signal intensity. By extending the duration of SAW exposure to 20 min, the binding amount can be significantly improved over the 60 min, 35 °C ELISA without SAWs. When introducing SAWs to the bead-based ELISA, the time required for binding can be further reduced to 2 min due to increasing depletion zone by acoustic streaming on beads surface. The sensitivity of ELISA can be significantly increased with lower LoD by combination of SAW stimulation and ultrabright fluorescent nanoscale labels. By significantly increasing the speed and sensitivity of ELISA, its utility may be improved for a wide range of point-of-care diagnostics applications.