Preparation Of Multistage Sustained-Release Drug-Loaded Short Nanofibers For Therapy Of Drug-Resistant Cancer Cells

Currently,chemotherapy is one of the most widely used cancer treatment methods due to its systemic treatment for whole body and obvious therapeutic efficacy.However,the problems such as repeated administrations,multidrug resistance and burst drug release resulting in damaging normal tissues and organs,have limited the further use of chemotherapy.Therefore,constructing a sustained-release drug delivery system with anti-multidrug resistance is the key to effective chemotherapy.The literatures show that the main cause of multidrug resistance in tumor cells is that P-glycoprotein(P-gp)over-expressing on cancer cell membrane pumps anti-tumor drugs out of cells.Alpha-tocopheryl succinate(?-TOS)can be used as a P-gp inhibitor to overcome the multidrug resistance of tumor cells.Among various drug nanocarriers,both layered double hydroxide(LDH)nanoparticles and electrospun nanofibers exhibit excellent drug-loading and drug-releasing properties.By directly treating the tumor,the injectable drug-loaded electrospun short nanofibers are able to overcome the drawbacks of low efficiency of drug-loaded electrospun fiber membrane in forms of dressing treatment,resulting in magnificent prospects in drug delivery application.In this thesis,we constructed drug-loaded LDH and ?-TOS doped polylactic acid-glycolic acid copolymer(PLGA)electrospun nanofiber and after shortened to micrometers in length,PLGA nanofibers were used for the treatment of resistant cancer cells.Firstly,LDH with high drug-loading rate and good biocompatibility was selected as the primary carriers to load chemotherapy drug doxorubicin(DOX);subsequently the formed DOX@LDH complex and ?-TOS were uniformLy mixed into the PLGA spinning solution.Then Electrospinning was carried out and the prepared PLGA nanofibrous membrane was homogenized to obtain multistage sustained-release DOX@LDH/?-TOS/PLGA short fibers.The nanofibers were characterized by various techniques.The results showed that: DOX@LDH was successfully synthesized,and the drug loading rate of DOX was 190.2%.The addition of DOX@LDH and ?-TOS made PLGA electrospun fibers thinner but had no obvious effect on the fiber morphology.DOX@LDH was uniformLy dispersed within the short fibers,and the homogenization process didn't affect the morphology.The length of the short fibers was about 17.4±7.3 ?m.The drug release profile demonstrated that at pH=6.8,?-TOS was first released from DOX@LDH/?-TOS/PLGA short fibers,while at pH=5.5,DOX in LDH was released first and the DOX release rate was 44.2% at 60 days.Secondly,MCF-7 and MCF-7/ADR cells were used to evaluate the biocompatibility and in vitro treatment efficacy of composite short nanofibers against multidrug resistance.The results showed that the dual-drug carrier LDH/PLGA electrospun nanofibers had excellent biocompatibility,and pure DOX had the greatest toxic side effects on cells.Compared with both single-drug loaded short nanofibers DOX/PLGA and ?-TOS/PLGA,dual-drug loaded short nanofibers DOX@LDH/?-TOS/PLGA could more effectively inhibit the growth of tumor cells and its inhibition efficiency was only next to that of pure DOX.Qualitative and quantitative analysis of the phagocytosis of DOX@LDH/?-TOS/PLGA short nanofibers using laser confocal microscopy and flow cytometry revealed that DOX@LDH/?-TOS/PLGA nanofibers was able to overcome the multidrug resistance of MCF-7/ADR cells by entering the cancer cells to kill them.In summary,we successfully constructed dual-drug loaded multistage sustained-release short nanofibers using an organic-inorganic dual carrier,which can overcome the multidrug resistance of tumor cells.The findings of this study provide a new idea for long-term effective treatment of drug-resistant tumor by only one or very few doses.