Preparation And Application Of The Dual-Modal Nanoprobes For Cancer Theranostics

Based on the statistics of the National Cancer Research Center,the number of cancer patients and the death have been increasing by about 4.57 million and by about 3 million each year in China,respectively,which seriously threaten human health.Early detection,early diagnosis and early treatment of cancer are of great significance to improve the survival rate of patients,to reduce the economic burden of families and to improve the health of the people.Along with the rapid development of cancers,a large amount of lactic acid,the metabolite of glycolysis,result in acidic tumor microenvironment,which further promotes tumor angiogenesis and lead to tumor metastasis.Therefore,for the acidic microenvironment of tumor and the neovascularization,the development of sensitive and effective imaging probes and new treatment technologies is of great significance to realize the accurate theranostics of tumor.With the aim of suppressing acidic microenvironment of tumor,we developed a gas diffusion method to prepare amorphous calcium carbonate nanoparticles（ACCICG NPs）loaded with indocyanine green（ICG）and modified by polyethylene glycol（PEG）to form the stable nano probes（ACC-ICG-PEG NPs）.The results showed that the size of the nano probe is about 90 nm and with good stability.The results of UVVis absorption and fluorescence spectra confirmed that ICG loaded in amorphous calcium carbonate nanoparticles and led to the fluorescence quenching of ICG dyes.The fluorescence signal of ACC-ICG-PEG NPs was significantly enhanced with the acid level enhanced from p H 7.4 to p H 6.5,showing a acid responsive effect.At the same time,the ACC-ICG-PEG NPs could decompose under acidic conditions to produce a large amount of carbon dioxide gas,resulting in the enhancement of ultrasonic signal.The above results showed that the prepared ACC-ICG-PEG NPs performed acid activable fluorescence / ultrasound imaging.We constructed tumor mouse model by implanting 4T1 cells subcutaneously and explored the imaging efficiency of ACC-ICG-PEG NPs in vivo.The results showed that after the ACC-ICGPEG NPs were injected into the tumor,the fluorescence / ultrasound signals in the tumor site were enhanced by 1.3-and 24.9-times respectively,which confirmed the good activatable imaging performance of the probe.In addition,after vein injection of the ACC-ICG-PEG NPs,the probes homed into tumor tissue due to the passive targeting effect,leading to the strong fluorescence signal at tumor site.Finally,we explored the therapeutic efficacy of the nanoprobes in vivo on 4T1 tumor mouse models.The results demonstrated that the ACC-ICG-PEG NPs mediated photothermal therapy combined with calcium therapy can effectively inhibit the growth of tumors.In conclusion,we successfully prepared an acidic activated fluorescence / ultrasound imaging nanoprobe,realized the fluorescence imaging and photothermal therapy combined with excess calcium ion therapy in the diagnosis and treatment of tumor on the mouse models for the theranostics of cancer.For tumor neovascularization,i RGD,a polypeptide molecule could target neovascularization and cross blood-brain barrier,was covalently coupled with nearinfrared dye ICG to form ICG-i RGD compounds;and then ICG-i RGD compounds were binded with human serum albumin（HSA）through hydrophobic interaction to form HSA-ICG-i RGD nanocomposites.The average size of the nanoprobe was about 11 nm.The fluorescence spectrum results showed that HSA-ICG-i RGD nanocomposites could improve the fluorescence intensity of ICG.The cellular uptake experiments showed that the HSA-ICG-i RGD nanocomposites could achieve active targeting by targeting the αvβ3 integrin receptor due to the existence of i RGD,which improved its cellular uptake efficiency.The results of near-infrared fluorescence and photoacoustic imaging show that HSA-ICG-i RGD nanocomposites can effectively aggregate in the glioma area,which proves that they have the ability of active targeting.The signal background ratio of in situ glioma the second near infrared imaging can reach 8.62,which realizes high-resolution and high-specific molecular fluorescence imaging.In the treatment experiment of tumor bearing mice,it was observed that HSA-ICG-i RGD nanocomposites had the best tumor inhibitory effect,and the survival time of orthotopic tumor mice could reach 55 days,which proved the excellent photothermal treatment effect of HSA-ICG-i RGD nanocomposites.In conclusion,we have successfully prepared a small-sized glioma-targeted HSA-ICGi RGD nanocomposites with photothermal therapy for the second near infrared fluorescence/photoacoustic dual-modality imaging,which has broad application prospects.