A piezoelectric ultrasound-assisted microjetting platform for high-throughput intracellular delivery

Efficient intracellular delivery of biomacromolecules and nanomaterials requires transient membrane permeabilization while preserving high cell viability, cell recovery, and processing throughput. However, conventional carrier-mediated delivery, electroporation, and passive mechanical extrusion approaches are often constrained by cargo-size limitations, cytotoxicity, limited processing throughput, or channel clogging. Here, we report a piezoelectric ultrasound-assisted microjetting platform for high-throughput, carrier-free intracellular delivery. The platform integrates a high-frequency piezoelectric actuator with a tapered micropore, enabling active ejection of cell suspensions through the nozzle. During microjetting, cells experience localized mechanical perturbation while passing through the micropore and undergo secondary deformation within the ejected droplets, which may promote transient membrane permeabilization. In addition, intra-droplet vortical flow may facilitate local cargo transport toward the cell membrane during the transient membrane-resealing window. Using this platform, we achieved efficient delivery of dextrans with different molecular weights (4-200 kDa), large plasmid DNA (9.3 kbp), polymer nanoparticles (100 nm), and quantum dots across multiple cell types while maintaining high cell viability and recovery. Under optimized conditions, the platform achieved delivery efficiencies of up to 86% and a processing throughput of up to 5 × 10⁷ cells per min. These results suggest that piezoelectric ultrasound-assisted microjetting offers a clogging-resistant strategy with potential for future scale-up in carrier-free intracellular delivery of biomacromolecules and nanomaterials.