Novel Span-PEG Multifunctional Ultrasound Contrast Agent Based on CNTs as a Magnetic Targeting Factor and a Drug Carrier

[Image: see text] Based on the targeting of ferroferric oxide (Fe(3)O(4)) and the drug-loading property of carbon nanotubes (CNTs), a novel Span-PEG-composited Fe(3)O(4)–CNTs–DOX multifunctional ultrasound contrast agent was designed and applied to tumor lesions. In situ liquid phase synthesis was employed to prepare the Fe(3)O(4)–CNTs magnetic targeting complex, and the physical method was used to obtain the Fe(3)O(4)–CNTs–DOX complex by loading doxorubicin (DOX) onto Fe(3)O(4)–CNTs. The targeted drug-loading complex Fe(3)O(4)–CNTs–DOX was combined with the membrane material of Span-PEG by the acoustic vibration cavitation method. The maximum tolerance for Span-PEG-composited Fe(3)O(4)–CNTs–DOX microbubbles was 450 times higher, which has good safety. The loading rate of DOX in the obtained composite microbubbles was 17.02%. The proliferation inhibition rate of Span-PEG-composited Fe(3)O(4)–CNTs–DOX microbubbles on liver cancer SMMC-7721 cells reached 48.3%. Span-PEG-composited Fe(3)O(4)–CNTs–DOX microbubbles could significantly enhance ultrasonic imaging and enrich at a specific location under an external magnetic field, and the extended imaging time could ensure the effective observation and diagnosis of lesions.