Preparation Of PH-responsive Nano Drug Delivery Systems Based On ZIF-8 And Their Antitumor Activity Research

Cancer is a serious threat to human health and life.Surgical treatment,radiotherapy and chemotherapy are traditional methods of clinical cancer treatment.Chemotherapy,the most commonly used clinical treatment,is limited due to the side effects of drugs and multidrug resistance?MDR?.Therefore,the drug delivery systems based on nanomaterials have emerged as ground-breaking candidates to overcome the disadvantages of chemotherapy.In the recent several years,various drug delivery systems based on the difference between normal and tumor tissues,including vascular pathophysiology,p H,oxygenation and enzyme activity have been designed.In order to realize the controllable drug release,different stimuli including magnetic field,pH and enzymatic activities have been employed.Among these,pH response is an important pathway for controllable release owing to the acidic pH in endo/lysosomal compartments of cancer cells.When the drug delivery systems were took into a specific location of cancer cells,the release of drugs by stimulating the environment to reduce the toxicity to normal tissue and cell.Furthermore,Nobel Prize winner Christian de Duve proposed a new cancer treatment method,which can kill cancer cells by destroying lysosomal membrane.When the drug acts on the lysosomes of cancer cells to improve the lysosomal membrane permeability,the lysosomes can release some specific tissue proteins to the cytoplasm,thus causing apoptosis or apoptosis like pathways.This method can effectively overcome the drug resistance of cancer cells and provide a new direction for cancer treatment.Therefore,lysosomes are considered as potential therapeutic targets for cancer therapy.MOFs have been attracted great attention due to their simple synthesis,large surface area and easy modification.In particully,ZIF-8 has grest potential application value due to its good biocompatibility,high drug loading and sensitive pH responsive degradation.Based on the above,two different pH responsive nanodrug delivery systems were constructed in this work.ZIF-8 was used to load the lysosomotropic detergent siramesine,and then modified with folic acid to obtain the first drug delivery system.DOX was loaded on ZIF-8 and then the nanoparticles were treated with NaHCO₃ and folic acid to obtain the orther pH responsive drug delivery system which can generate bubbles.The details are as follows:?1?The construction of a targeted pH-responsive Nano-delivery systemThe carriers of the drug delivery nanosystem were first constructed by coordination between Zn²⁺and 2-MIM.Due to the chelation with Zn²⁺and?–?interaction with2-MIM,siramesine was then loaded into the ZIF-8 in the second step of the synthesis process.Lastly,PEG–FA was selected for the final nanoparticle modification to obtain the drug delivery systems ZIF-8@Sira/FA.First of all,we confirmed the successful synthesis of the material by the color change in the process of nanomaterial synthesis,transmission electron microscopy?TEM?,FT-IR spectra and Zeta potential.Then,ZIF-8@Sira/FA has been proved to have sensitive pH response and good biocompatibility by Drug release assay in vitro and the toxicity text of ZIF-8/FA against cancer cells.Hence,ZIF-8@Sira/FA,which has sensitive pH response degradation and good tumor targeting,has a broad application prospect in cancer theraty.?2?Inhibitory effect of BGNSs@pDA-FA on MCF-7,MCF-7/ADR and MCF-10A cellsMCF-7,MCF-7/ADR and MCF-10A cells were used to investigate the effect of ZIF-8@Sira/FA on cells.Fluorescence co-localization,lysosomal membrane permeability assay,and lactate dehydrogenase assay were used to study the mechanism of ZIF-8@Sira/FA.In vitro antitumor activity of drug delivery systems showed that ZIF-8@Sira/FA exhibits better anticancer effects and little side effects on normal tissues.Fluorescence co-localization experiments confirmed that most of the materials in this study entered lysosomes,and a few entered the cytoplasm with the lapse of time,which is because of the drug release after the collapse of the material structure.The lysosomal membrane permeability assay confirmed that ZIF-8@Sira/FA can increase the lysosomal membrane permeability.The lactate dehydrogenase assay was performed to verify that ZIF-8@Sira/FA causes cancer cell death through apoptosis or similar apoptosis pathway instead of necrosis.Folic acid competition experiments showed the successful modification of folic acid in ZIF-8@Sira/FA and successful targeting of cancer cells.In summary,this work provides a potential application of non-anticancer drugs for cancer therapy through lysosomal cell death pathway and expands the utilization of ZIF-8 in the biomedical field for anticancer therapy.?3?The construction of amide bond-based drug delivery system and its anti-cancer researchIn this work,DOX was loaded on ZIF-8 and the nanomaterials were treated with NaHCO₃ according to the method previously used in our research group.Then,PEG-FA was modified to prepare the nano drug delivery system ZIF-8@DOX+NaHCO₃/FA.Firstly,we proved the successful synthesis of the nano drug delivery system by TEM,zeta potential and FT-IR spectra.Then the drug release assay in vitro confirmed that the drug can be effectively released in the weak acid environment.The inhibition of ZIF-8@DOX+NaHCO₃/FA on the activity of MCF-7 and MCF-7/ADR cells was further investigated,which confirmed that ZIF-8@DOX+NaHCO₃/FA has low biotoxicity and excellent cytotoxicity to cancer cells.Compared with DOX,ZIF-8@DOX+NaHCO₃/FA can kill drug resistant cells more effectively and overcome drug resistance to some extent.