Phase Transition Nanoparticles As Multimodality Contrast Agents For The Detection Of Thrombi And For Targeting Thrombolysis

Objective: To prepare EWVDV-modified multi-functional nanoparticles(EWVDV-Fe-Ink-PFH NPs)and detect their physicochemical properties,the characteristics of the photoacoustic,magnetic resonance and ultrasound imaging in vitro,thrombolytic in vitro,the targeting ability of the NPs and multimodal imaging in vivo.Methods: Three-step emulsification method and carbodiimide method were used to construct EWVDV-Fe-Ink-PFH NPs.Particle size potentiometer,fluorescence microscope,flow cytometer,atomic absorption spectrometer,transmission and scanning electron microscopy were used to characterize the physicochemical properties of nanoparticles.Multimodal imaging characteristics and thrombus imaging in vivo were studied using photoacoustic imager,magnetic resonance imaging and ultrasound imager.Phase transition thrombolysis was studied by low intensity focused ultrasound(LIFU)in vitro.Results: The EWVDV-Fe-Ink-PFH NPs were gray emulsions with uniform size,smooth surface and good dispersion.Scanning electron microscopy(SEM)showed a regular spherical shape.Transmission electron microscope(TEM)showed uniform iron oxide particles were distributed on the nanoshells;fluorescence microscopy showed red fluorescence around the NPs,indicating that the Rhodamine-labeled peptide EWVDV was successfully linked to the surface of Fe-Ink-PFH NPs.Flow cytometry showed that the target ratio was 63.48%.The NPs size was387.1 ± 129.1 nm,and the polydispersity index(PDI)was 0.09 ± 0.032,indicating that the NPs were well-dispersed.The potential was-23.2±3.4mV,and the Fe content was 4.29±0.27 ?g Fe/mg PLGA.Photoacoustic,magnetic resonance,and ultrasound imaging were successfully demonstrated in vivo.Excellent penetration and targeting properties of NPs were verified on the inferior vena cava and abdominal aortic thrombi by pathology and multimodal imaging.The thrombolysis was successfully achieved by LIFU-induced phase transition technique and the thrombolytic rate reached 27% at 30 minutes.Conclusion: The successful construction of multi-functional nanoparticles(EWVDV-Fe-Ink-PFH NPs)can not only be used for thrombus photoacoustic,magnetic resonance,ultrasound imaging in vitro and in vivo,but also has the function of targeted thrombolysis,which is a simple,safe and effective contrast agent for diagnosis and treatment.