Study On The In Vitro Targeting And Imaging Performance Of Aptamer Modified Targeted Ultrasound/Photoacoustic Dual-Modality Contrast Agent

PARTⅠPREPARATION OF APTAMER-PLGA NANOPARTICLE AS TARGETED, PHASE-TRANSITION BASED ULTRASOUND/PHOTO ACOUSTIC DUAL-MODALITY IMAGING CONTRAST AGENTObjective To synthesize an aptamer-labeled ultrasound/photoacoustic dual-modality imaging contrast agent loaded with gold nanorods and liquid perflurocarbon, and further investigate its phase-transition property.Methods The aptamer-labeled PLGA nanopartIcle contrast agent was loaded with gold nanorod and liquid perflurocarbon. The nanoparticle was synthesized via double emulsion technique and the conjugation with aptamer was achieved with carbodiimide technique. The targeted, phase-transition capable nanoparticle was irradiated with nanosecond pulsed laser to investigate its phase-transition property.Results The aptamer labeled PLGA nanoparticle with a mean diameter of (472.4±25.8) nm was successfully prepared. After irradiation with laser, significant phase-transition phenomenon of the nanoparticle was observed.Conclusion The aptamer was successfully conjugated to the PLGA nanoparticle which was loaded with gold nanorod and liquid perflurocarbon. Due to the excellent phase-transition property, the targeted nanoparticle has great potential to become a distinguished ultrasound/photoacoustic contrast agent, which lays a good foundation for further in vitro/vivo targeted experiment and ultrasound/photoacoustic imaging application.PART Ⅱ STUDY ON THE IN VITRO TARGETING AND IMAGING PERFORMANCE OF APTAMER MODIFIED TARGETED ULTRASOUND/PHOTO ACOUSTIC DUAL-MODALITY CONTRAST AGENTObjective To study the targeting ability of aptamer-modified PLGA nanoparticle encapsulated with gold nanorod and liquid perflurocarbon, and observe its mediated ultrasound/photoacoustic dual-modality imaging in vitro.Methods PLGA nanoparticle was prepared using double emulsion technique. Aptamer-modified PLGA nanoparticle was obtained by connecting Then, PLGA nanoparticle was conjugated with MUC1 aptamer carbodiimide technique aimed to obtain aptamer-modified PLGA nanoparticle. Targeting ability of aptamer-modified PLGA nanoparticle to MCF-7 tumor cells in vitro was tested by fluorescence microscope. Besides, there were three control groups including PLGA nanoparticle group, aptamer group and HELA cell group. A commercial photoacoustic instrument was used to detect ultrasound/photoacoustic signal.Results A significant number of aptamer-modified PLGA nanoparticles gathered around the MCF-7 cells, however, the specific binding can not be observed in control groups. Both ultrasound and photoacoustic signal intensity of the aptamer-modified PLGA nanoparticles increased significantly when excited with laser.Conclusions The aptamer-modified PLGA nanoparticle was successfully prepared, and had superior targeting ability to MCF-7 cells, Morever, ultrasound/photoacoustic signal emitted the by nanoparticle increased significantly. These properties make the targeted nanoparticle a great potential to become a distinguished ultrasound/photoacoustic dual modality contrast agent, which lays good foundation for further targeted imaging application in vivo.