Schematic illustration of neutrophil-mediated chemotherapeutic drug delivery for suppression of tumor recurrence after HIFU ablation. HIFU-induced cell death creates an inflammatory environment in the residual tumor (1a and b), and the released chemokines induce neutrophils to migrate to the tumor site (2). PLD@NEs transmigrate to the vascular barrier and penetrate into the residual tumor along the chemotactic gradient (3). PLD is released from neutrophils to produce an antitumor effect via NET formation (4)