| The effective load and safe delivery of therapeutic drugs to tumor tissues are the key to effective cancer treatment.However,classical chemotherapy drugs usually have poor stability,poor water solubility and side effects and so on.The genomic drugs are easy to be degraded in vivo.Moreover,metallodrugs such as cisplatin have a good inhibitory effect on tumors.The main limitation of metallodrugs is their potential instability in the blood and their oxidation profile.The rapid development of nanotechnology has greatly promoted the efficient anti-cancer treatment.The excellent nanocarriers can effectively overcome the problems of anticancer drugs.In recent years,various nano-carriers such as liposomes,mesoporous silicon,nano-gels,micelles,polymers and so on have been developed.However,there are still great challenges in the field of nanomedicine to build stable,efficient and safe nanocarriers.Among varieties of nanocarriers,application of PAMAM in nanomaterials has received the greatest attention,because of their advantages of neat structure,internal cavity,and numerous surface functional groups.However,the amino groups of its surface have cytotoxicity.Surface modification is usually way to improve biocompatibility.In addition,due to the insufficient rigidity of the PAMAM,it is necessary to introduce metal nanoparticles to improve its ability of the gene delivery.Because of phosphorus is closely related to life activities,phosphorus is increasingly used in the field of nanomaterials.Phosphorus atoms in various positions in their structure of phosphorus dendrimers present undoubtedly the largest variety of constitutive elements of the core,branching units,internal branches,backbones,and surfaces due to the fascinating versatility of the organophosphorus chemistry.Therefore,we expect that the advantages of the two materials can be combined by introducing phosphorous elements into dendrimers and to provide materials for the construction of new efficient,stable and safe nanocarriers.Phosphorus dendrimers not only have high branching,symmetrical structure,and uniform molecular weight distribution,but also have unique biological characteristics because of the introduction of phosphorus.The aim of this work was to design several families of ionic phosphorus dendrimers/dendrons,and to investigate their potential in the field of nanocarriers for gene/metal ion/hydrophobic drugs delivery,and to lay the experimental foundation for commercialization.Meanwhile,these works provide theoretical basis and new ideas for the application of other types of nanomaterials in the field of nanocarriers.(1)In chapter 2,we revisit the development of cationic phosphorus dendrimers by synthesizing them with different generations(G1-3)and surface ligands(1-(2-aminoethyl)pyrrolidine,1-(3-aminopropyl)piperidine,or 1-(2-aminoethyl)piperidine)for optimized gene delivery toward cancer gene therapy applications.First,the synthesized dendrimer derivatives were employed to condense plasmid DNA(p DNA)encoding enhanced green fluorescent protein(EGFP)to optimize their gene delivery efficiency by varying the dendrimer generations and surface polycationic ligands.We show that all dendrimer/p DNA polyplexes display good cytocompatibility,and the 1-(2-aminoethyl)pyrrolidine-modified protonated G1 dendrimers(1-G1)display the best gene delivery efficiency to He La cells under the same conditions through flow cytometry and fluorescence microscopic imaging analyses.Hence,1-G1 dendrimers were then used as a vector to transfect p DNA encoding both EGFP and p53 protein for cancer gene therapy applications.Our results reveal that under the optimized conditions,the transfection of p DNA induces the significant p53 protein expression as verified through the resulted cell cycle arrest and Western blotting.The cancer gene therapy potential of the polyplexes was finally validated through therapy of a xenografted tumor model after intratumoral injection without systemic toxicity.(2)In chapter 3,metal ions and alkyl chains were introduced into the optimized generation of phosphorus dendrimers base on the chapter 2.We prepared four different dendrons bearing two distant linear alkyl chains,and bearing ten N-(pyridin-2-ylmethylene)ethanamine groups to complex Cu(II)and Au(III).These metaled phosphorus dendrons were used as metal drugs in cancer therapy.The data suggest that the cytotoxicity increases with reducing the length of the alkyl chains,whereas the replacement of Cu(II)by Au(III)considerably increases the antiproliferative activity of metaled phosphorus dendrons.The four metaled phosphorus dendrons(10 μM)enhanced the frequency of apoptotic nuclei in 4T1 cells.Meanwhile,those metaled phosphorus dendrons were more potent promoters of cell cycle arrest(phase S)in 4T1 cells.We found that the cell death pathway is related to the nature of the metal complexed by the plain dendrons.Cu(II)metaled dendrons showed a potent caspase-independent cell death pathway;whereas Au(III)metaled dendrons displayed a caspase-dependent apoptotic pathway.The complexation of plain dendrons with Au(III)increased the cellular lethality versus dendrons with Cu(II)and promoted the translocation of Bax into the mitochondria and the release of Cytochrome C(Cyto C).(3)In chapter 4,alkyl chains were introduced into the cationic phosphorus dendrimers base on the chapter 2.We prepared the amphiphilic phosphorus dendron 1-C12G1 bearing a long linear alkyl chain(C12H25),and bearing ten protonated pyrrolidine groups in the surface.1-C12G1 forms stable nanomicelles which allow to encapsulate anticancer drug DOX and complex the mi R-21 inhibitor for synergistic therapy of triple negative breast cancer cells.The data suggest that the encapsulation and loading efficiency of DOX can reach up to 99.81% and 82.1%.Meanwhile,the 1-C12G1@DOX/mi R-21 i was stable in NS and cell medium and had a good sustained drug release effect under acidic conditions.The data of flow cytometry and WB showed that co-delivery of DOX and mi R-21 i could achieve synergistic effects on tumor suppression. |
