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Ultrasound can promote the drug release from drug-loaded substances and alter the tumor local microenvironment to facilitate the transport of drug carriers into the tumor tissues. Based on the altered tumor microenvironment, nanobubbles (NBs) as drug carriers with surfaces functionalized with targeting ligands can reach the tumor sites, thereby increasing the efficacy of chemotherapy. Herein, paclitaxel (PTX)-loaded poly(lactide-co-glycolide) (PLGA) NBs are prepared as drug carriers with covalently conjugated herceptin (anti-HER2 monoclonal antibody) on the surface to guide the target. The effect of ultrasound on the drug release and targeting of the herceptin-conjugated drug-loaded nanobubbles (PTX-NBs-HER) on the cancerous cells is determined. The use of ultrasound significantly improves the cell targeting capability in vitro, and efficiency of enhanced permeability and retention in vivo. The combination of PTX-NBs-HER and ultrasound facilitates the release of PTX, as well as the uptake and cell apoptosis in vitro. The in vivo application of both PTX-NBs-HER and ultrasound enhances the PTX targeting and accumulation in breast cancers while reducing the transmission and distribution of PTX in healthy organs. The combination of ultrasound with PTX-NBs-HER as contrast agents and drug carriers affords an image-guided drug delivery system for the precise targeted therapy of tumors.