Ultrafast no-wash bioassay based on gold nanoparticles and enhanced by acoustic streaming

No-wash bioassays based on nanoparticles are used widely in biochemical procedures because of their responsive sensing and no need for washing processes. Essential for no-wash biosensing are the interactions between nanoparticles and biomolecules, but it is challenging to achieve controlled bioconjugation of molecules on nanomaterials. Reported here is a way to actively improve nanoparticle-based no-wash bioassays by enhancing the binding between biomolecules and gold nanoparticles via acoustic streaming generated by a gigahertz piezoelectric nanoelectromechanical resonator. Tunable micro-vortices are generated at the device–liquid interface, thereby accelerating the internal circulating flow of the solution, bypassing the diffusion limitation, and thus improving the binding between the biomolecules and gold nanoparticles. Combined with fluorescence quenching, an enhanced and ultrafast no-wash biosensing assay is realized for specific proteins. The sensing method presented here is a versatile tool for different types of biomolecule detection with high efficiency and simplicity.