Preparation Of Muti-functional Nanosystem And Its Application In Cancer Theranostic

The thesis was devoted to developing multi-functional nanosystems with cancer theranostic and controlled release of anticancer drugs.The ⁶⁴Cu-labeled targeted nanopharmaceuticals were transported together to the site of the tumor to achieve diagnosis and treatment of the tumor.The prepared multifunctional theranostic nano-system that an efficient,low-toxic nano carrier has excellent application prospects.The study of nanocarriers provides a basis for the application of multi-function tumor-targeted nanometer delivery systems for diagnosis and treatment.The research content was shown as follows:1.The establishment of multifunctional nano-system.The dendrimers PAMAM-OH was the main structure,covalently attached to hydrophilic chain of polyethylene glycol（PEG）and hydrophobic of polyaspartic acid（PBLA）.The tumor targeting F3 peptides and NODA,a macrocyclic chelator for ⁶⁴Cu(t_1/2=12.7h),were selectively conjugated onto the distal ends of the PEG arms.DOX was conjugated onto the hydrophobic segment（PBLA）of nanocarriers via a pH-sensitive hydrazone bond to enable pH-controlled release.To obtain the dendritic amphiphilic block copolymer PAMAM-P（LA-Hyd）-DOX)-b-PEG-OCH3/F3/NODA will be referred to as PAMAM-DOX-F3.¹H NMR spectra of all intermediate and final polymer products were recorded,and the molecular weight of the polymers was determined by gel permeation chromatography（GPC）.2.The morphology,drug loading,drug release,and stability of the prepared unimolecular micelles were evaluated.The results of transmission electron microscopy（TEM）and dynamic laser scattering（DLS）indicate that the micelles were regular spherical and have a size of 20-37 nm.The content of the drug in the nanomicelle was 16.5%,which was determined by ultraviolet-visible spectr-ophotometer（UV）.The PH response mechanism was evaluated by the release of drug accumulation,and the results showed that the cumulative release amount was as high as 80%under the condition of pH 5.3,however,under the condition of pH 7.4,the cumulative release amount was only 16%.It was found that there was no notable change in both the appearance over 21 days in a simulated physiological stability test.These data indicate that the nanomicelles have excellent blood circulation stability.3.In vitro cell biological activity evaluation of unimolecular micelles.Flow cytometry and confocal fluorescence microscopy observed consistent cellular uptake,Targeting PAMAM micelles（PAMAM-DOX-F3）and non-targeting PAMAM micelles（PAMAM-DOX）specifically accumulate in MDA-MB-231 human breast cancer cells.In addition,the MDA-MB-231 tumor cytotoxicity analysis also confirmed that the PAMAM-DOX-F3 targeting unimolecular micelles have stronger internalization.These indicates that it has a relative targeting effect.4.In vivo performance evaluation of unimolecular micelles.With the incorporation of a positron-emitting isotope ⁶⁴Cu,pharmacokinetic performance of radiolabeled PAMAM micelles can be monitored in vivo by positron emission tomography（PET）imaging in vivo.Serial PET imaging demonstrated that ⁶⁴Cu-PA-MAM-DOX-F3 possessed potent and persistent uptake in MDA-MB-231 tumors（6.1±1.2%injection dose per gram[%ID/g]at 24 h p.i.）,significantly higher than that of⁶⁴Cu-PAMAM-DOX（2.5±0.4%ID/g at 24 h p.i.）,while their distribution profile in other organs/tissues were quite similar.These data illustrate the ability of targeted nanomicelles to have potent and long-lasting uptake at the tumor site.In addition,ex vivo fluorescence imaging showed that the uptake of F3-targetin micelles was stronger than non-targeted micelles at tumor sites,it was indicating that PAMAM micelles could deliver DOX efficiently to tumor region.Fruthermore,there was no DOX fluorescence in the heart.