| microRNA(miRNA)represents a promising class of therapeutic nucleic acid drugs.It can degrade mRNA or inhibit protein translation by complementary target messenger RNAs,leading to cells apoptosis.While delivery challenges remain that impede the advancement of miRNA therapy,largely due to in vivo instability and low delivery efficiency.Therefore,it is necessary to develop delivery carriers.In this thesis,the preparation,drug loading capacity,pH responsive release,serum stability and antitumor effect in vivro and vivo of metal-organic frameworks(ZIF-8)-based miRNA drug carriers were studied.The main research work is summarized as follows:In chapter one,we introduce the advantages and remaining challenges of cancer therapy based on miRNA,summarize the characteristics and development of MOFs as new drug carrier,and finally put forward the significance and content of this research.In chapter two,we prepared miR-34a@ZIF-8 by electrostatic adsorption and further explored loading capacity of ZIF-8,up to 36 μg miR-34a per mg ZIF-8.Scanning electron microscopy showed that miR-34a@ZIF-8 was regular polyhedral shape with particle size of about 148.3±9.7 nm.The release experiment under different pH conditions showed that Cy5-miR-34a@ZIF-8 was acid responsive and could be released rapidly under pH 5.5 condition.The serum stability experiment showed that ZIF-8 could prevent the degradation of miR-34a by RNase in serum,so miR-34a@ZIF-8 showed very high serum stability.In chapter three,we studied the antitumor effect of miR-34a@ZIF-8 in vitro.The cellular uptake experiment showed that ZIF-8 could promote miR-34a to enter cells.ROS detection experiment showed that miR-34a@ZIF-8 could generate ROS inside cell,which had potential cytotoxicity.Combined gene/chemodynamic therapy effects of miR-34a@ZIF-8 were better than individual miR-34a or ZIF-8 by results of cytotoxicity,RT-qPCR and western blot.In chapter four,we explored the antitumor effect of miR-34a@ZIF-8 in vivo.Results of the body weights,blood chemistry indexs,hemolysis rate and tissue H&E staining sections showed that miR-34a@ZIF-8 was good biosafety in vivo.Biodistribution experiment showed that Cy5-miR-34a@ZIF-8 could be accumulated in tumor site through EPR effect.The miR-34a@ZIF-8 group exhibited significant tumor suppressive effect compared to miR-34a group or ZIF-8 group by monitoring tumor volume changes of tumor-bearing mice.In chapter five,we made a conclusion and outlook.We have developed this MOFs-based miRNA drug carrier will provide a promising strategy for RNA delivery and combined gene/chemodynamical tumor therapy. |
