The Preparation And Application Of Novel Magnetic Nanoprobes For Tumor Diagnosis And Therapy

BACKGROUNDNanomaterials are increasingly used in the diagnosis and treatment of tumors,mainly including various nanovesicles,lipids,proteins,and complex biological macromolecules.They can participate in the regulation of functions in vivo,but also be served as drug carriers to delivery active molecules.The earlier examples of nanomedicine such as lipid and polymer-based nanocarriers,could deliver targeting drugs and sustained chemotherapeutic drugs.At present,there is increasing awareness of novel medical applications of inorganic-based nanoparticles,which have unique properties at the nanoscale,leading to the development of"nanoprobes"for diagnostic medicine and new applications on therapeutic agents via external activation.Magnetic-based nanomedicens for diagnosis and nanoparticle-mediated drug delivery can be collaborated and reached the super-additive effect for tumor diagnosis and treatment?"1+1>2"?,that may bring unprecedented advances in medicine.This article will explore the effects of nano-diagnosis and nanotheranostic treatment.MethodsExperiment 1:A zwitterionized biodegradable dendritic contrast agent G4-MOP-DTPA-Gd was synthesized,thus was characterized in vitro,including nuclear magnetic characterization,average particle size and particle size distribution,degradation rate and longitudinal relaxivity.Blank mice were injected G4-MOP-DTPA-Gd nanoparticle solution and performed MRI to observe normal liver metabolism by Discovery 750w 3.0T MRI,GE Healthcare system.Subsequently,4T1-bearing liver metastasis mice model was established and performed MRI.Small contrast agent Magnevist or G4-MOP-DTPA-Gd nanoparticle for the same mice was injected and measured MRI signals of metastases and normal liver(0.1 mmol Kg^-1 Gd,4 mice per group).The gross liver samples with liver metastases were extracted and then were compared with MRI to confirm the location of metastatic tumors.Finally,blank mice were injected with G4-MOP-DTPA-Gd nanoparticle,and the main tissues and organs were taken out to measure Gd³⁺content by Inductively coupled plasma mass spectrometry and then calculated.Experiment 2:Theranostic nanoparticles DHM was synthesized using dendrimers with cysteine as carriers for hypericin and Mn Cl₂ co-delivery.Firstly,characterization of DHM nanoparticle in vitro,including nuclear magnetic characterization,average particle size and particle size distribution,longitudinal relaxivity and MRI.The 4T1 cell line was used to test cytotoxicity,endocytosis ability,and reactive oxygen species release ability.Subsequently,orthotopic breast cancer mice model of the 4T1 cell line was established,and followed 3.0 T MRI to perform enhanced MRI of breast cancer.The MRI signals of the tumors before and after the injection of DHM nanoparticles were compared.In addition,4T1 tumor-bearing mice were randomly divided into 4 groups to investigate the efficiency of DHM combined with photodynamic therapy.All the mice were administered drugs only once(Hypericin equivalent 10?g Kg^-1,5 per group),and the tumor growth and body weight changes were observed.Finally,blank mice were injected with DHM nanoparticles and MRI was performed to observe the systemic distribution and metabolism of the nanoparticles over time.Experiment 3:A simple one-pot method was used to obtain BHM nanoparticles by mixing bovine serum albumin,hypericin and Mn Cl₂.Firstly,the average particle size,longitudinal relaxivity were measured,and MRI was performed in vitro.The 4T1 cell line was used to test its cytotoxicity,endocytosis ability,and reactive oxygen species releasment ability.Subsequently,orthotopic breast cancer mice model of the 4T1 cell line was established,and 3.0 T MRI was used to perform enhanced MRI of breast cancer.The MRI signals of the tumors before and after injection of BHM nanoparticles(0.1 mmol Kg^-1 Mn)were compared.In addition,4T1 tumor-bearing mice were randomly divided into 4 groups to investigate the efficiency of DHM combined with photodynamic therapy.All the mice were randomly divided into 4 groups and administered only once(Hypericin equivalent 5?g Kg^-1,5 mice per group),and the tumor growth and body weight changes were observed.Finally,blank mice were injected with BHM nanoparticles and MRI was performed to observe the systemic distribution and metabolism of the nanoparticles over time.ResultsExperiment 1:Firstly,the 4th generation of zwitterionized biodegradable dendritic contrast agent G4-MOP-DTPA-Gd was synthesized,with an average particle size of about9 nm and longitudinal relaxivity value of 15.7 m M^-1 s^-1.In addition,G4-MOP-DTPA-Gd could be degraded into small fragments at physiological p H,with an accelerated degradation by esterase.The liver metastasis model mice injected with G4-MOP-DTPA-Gd performed MRI and showed clearly intrahepatic metastatic lesions,with a maximum of CNR 65,while Magnevist could hardly identify tumor lesions.Finally,compared with non-biodegradable dendritic contrast agent,G4-MOP-DTPA-Gd had less long-term Gd³⁺retention in major organs or tissues.Therefore,G4-MOP-DTPA-Gd had good capability of enhancing MRI of intrahepatic metastatic tumor with good biodegradability,thus was demonstrated as a promising contrast agent for tumor metastasis imaging.Experiment 2:Firstly,manganese-based polyester dendritic macromolecule contrast agent DHM was synthesized with an average of particle size of 109 nm,particle size distribution of 0.151,zata potential of-7.2 m V,and good dispersion in different solution environments.Then,cytotoxicity experiments on 4T1 cell experiments on cytotoxicity showed that DHM plus light group had the strongest cytotoxicity,and the killing ability of tumor cells may mainly contribute from the increasing of reactive oxygen species.4T1tumor-bearing mice injected with DHM nanoparticles showed high CNR from tumor site,and reached about 62 at 60 min.Then,the group with DHM combined with light showed completely tumor disappeared,indicating that DHM nanoparticles had efficient tumor inhibition ability.In addition,DHM nanoparticle showed good biological compatibility from the observation of mice body weight change during treatment,H&E staining of organs and tissues,and MRI images of blank mice after injection of DHM.Experiment 3:A simple mixture of bovine serum albumin,hypericin and manganese was used to efficiently prepare theranostic BHM nanoparticle.BHM nanoparticle in vitro had the advantages of efficient response cracking in tumor microenvironment with high longitudinal relaxivity(9.04 m M^-1 s^-1)and high PDT effect.For imaging experiments in vivo,BHM nanoparticle could react with H₂O₂ within tumor site for O₂ release to alleviate hypoxia,and release Mn²⁺to enhance MRI.For tumor inhibition experiments in vivo,mice with single administration of BHM combined with photodynamic therapy could effectively inhibit tumor growth.In addition,MRI images of blank mouse treated with BHM nanoparticles were metabolized through liver and kidney,and were basically expelled from the body one day after administration,showing high biocompatibility.ConclusionsThe above results were summarized as follows.?1?The zwitterionized biodegradable dendritic contrast agent G4-MOP-DTPA-Gd showed high relaxivity rate with high MRI detection efficiency for liver metastases in mice,and had excellent biocompatibility;?2?Manganese-based polyester dendrimer macromolecule contrast agent DHM had high longitudinal relaxivity with high MRI detection efficiency for mouse with breast cancer in situ,and had good PDT efficacy for breast cancer;?3?The theranostic nanoparticles BHM prepared by the one-pot method with high longitudinal relaxivity.It had high MRI detection for mouse with breast cancer in situ and a good PDT effect on inhibiting breast cancer growth.With the visualization of diagnosis,tumor treatment can gain huge improvement.The nanotheranostic system possess the advantage of accurate diagnosis and efficient treatment,breaking the limitations of the separation of diagnosis and treatment.