Preparation Of Nanomaterials In Response To Tumor Microenvironment And Research On Ultrasound Imaging And Therapy

Part Ⅰ Smart responsive-calcium carbonate nanoparticles for dual-model cancer imaging and treatmentObjective: Ultrasound imaging plays a critical role in the cancer diagnosis 、 therapeutic and monitoring,ultrasonic contrast agent is a key factor to improve image quality.Currently,the size of the microbubble imaging agent for clinical use is larger,mainly located in the blood vessels and used in angiography,it’s difficult to get directly into tumor tissue.In this study,with the help of calcium carbonate nanomaterials,we developed a kind of tumor microenvironment sensitive nanoparticles for molecular imaging of tumors anddrug delivery.Methods:Firstly,DOX loaded calcium carbonate nanoparticles were prepared,The loading of DOX and the degradation of DOX nanoparticles were characterized by UV Vis absorption spectroscopy and transmission electron microscopy,respectively.Ultrasound was used to verify the efficacy of composite nanoparticles ultrasound contrast agentin vitro,UV-Vis spectrophotometerwas used to measure the regulationand release of doxorubicin.Subsequently,we verified the uptake of CaCO₃-dox nanoparticles in cells and its inhibitory effect on the growth of tumor cell in vitro.Finally,we studiedthe accumulation of nanodrugs 、 ultrasound imaging and its inhibitory effect on the growth of tumorin tumor-bearing mice.Results: CaCO₃-DOX NPs indicated their excellent colloidal stability under the physiological p H,they slowly dissociated in PBS at p H 6.0,generated CO₂ gas to enhance the ultrasound contrast.The contrast intensity of ultrasound imaging is increased nearly 4 times,and the time is prolonged nearly 20 times compared with traditional ultrasound contrast agent.In vivo experiments suggested that,CaCO₃ nanoparticles could entrap into tumor with EPR effect and release CO₂ gas in the acidic microenvironment of tumorfor a more extended time and hence leading to an accurate diagnosis.The continuousrelease of DOX from the CaCO₃-DOX NPs at the acidic environment oftumor could be taken up by the tumor cells,allowing for the enhancedantitumor effect.Conclusion: In summary,we have successfully developed a tumor microenvironment-responsive CaCO₃-DOX hybrid nanoparticles for the dual-mode tumor detection and treatment.The developed nanoparticles could disrupt toproduce CO₂ for enhanced US imaging.Meanwhile,the DOX effectivelyreleased nearly 4-fold under acidic condition.After accumulating in thetumor,the acidic microenvironment could trigger CO₂ bubbles to improve the quality of US imaging.Besides,the effective release of DOXsignificantly inhibits tumor growth.All these results demonstrate thatthe proposed CaCO₃ hybrid nanoparticles could be a promising drugdelivery carrier for cancer theranostics with potential clinical applications.Part Ⅱ HSA-MnO₂ nanoparticles used to ultrasound molecular imaging forcancerObjective:The tumor tissue is weakly acidic,and the content of hydrogen peroxide（H₂O₂）near the tissue is high.Aimed at the special microenvironment of tumor,we designed and synthesized HSA-MnO₂ nanoparticles,delivering specific substances to interact with tumor microenvironment,the local oxygen released within tumors,improved tumor cell hypoxia.Meanwhile,this procedure can enhance the contrast of ultrasound,simultaneous improved theimaging and antitumor activity.Methods:First,HSA-MnO₂ nanoparticles were developed and characterized for in vitro physicochemical properties,Oxygen production of HSA-MnO₂ nanoparticles was measured by oxygen analyzer in vitro.Subsequently,HSA-MnO₂ nanoparticles was dissolved and diluted in PBS solution with p H = 6.5 and p H = 7.4 and then were studied by ultrasonography,the ultrasonic images and parameters were recorded,the imaging performance ofnanoparticles was analysed.Finally,small animal ultrasound was used to observe the metabolic distribution of nanoparticles in the main organs of normal mice and muscle invasive bladder cancermice,the imaging performance ofnanoparticles was analysed in vivo.Results:The HSA-MnO2 nanoparticles exhibited a well-defined spherical structure with good stability and monodispersity.After adding H₂O₂,nanoparticles can produce a lot of oxygen.the reaction of MnO₂ with H₂O₂ was accelerated in an acidic condition.The ultrasonic signal was significantly enhanced at p H =7.4,10 minutes later,the intensity of ultrasonic signal is enhanced by 4.6 times at p H =7.4 and 7.7 times at p H =6.5.Vivo study showed that,after injection of HSA-MnO₂ nanoparticles for 24 hours,the ultrasonic signal of tumor tissue was signally enhanced,compared with that before injection,the strength increased by 2.5 times.Conclusion:HSA-MnO₂ nanoparticles can improve the hypoxic state of tumor site,the oxygen produced by nanoparticles can enhance the ultrasonic reflection and play the role of contrast-enhanced ultrasound.In summary,the HSA-MnO₂ nanoparticles can produce oxygen in response to tumor microenvironment,it is expected to be an ultrasound contrast agent for tumor and improve the therapeutic effect of tumor.