Functional Modification Of PLA@ZIF-8 Nanofiber Membrane And Study On Drug Sustained Release Properties

Electrospinning is one of the most convenient techniques for preparing nanofibers.Electrospinning nanofiber has the advantages of large specific surface area,high porosity and controllable fiber size which are widely used in biomedical materials,wound dressings,tissue engineering and other fields and it also has a broad application prospect in the field of drug sustained release.Zeolite imidazolate framework-8(ZIF-8)is widely used in gas separation,catalysis,drug carrier and other fields due to its adjustable pore size and high specific surface area.In this paper,polylactic acid(PLA)nanofiber membranes were prepared via electrospinning technology.Astragalus polysaccharide(APS)was selected as the model drug and PLA@ZIF-8 composite nanofiber membranes were obtained by the secondary growth method for sustained drug release.The influences of the secondary growth time and 2-methylimidazole(2-MIM)concentration on the morphology,distribution of ZIF-8 and membranes surface properties were investigated.In order to solve the problem of poor efficacy of single drug-loading system,PLA/CS nanofiber membranes capable of loading two-component drugs were prepared by emulsion electrostatic spinning,which water in oil(W/O)emulsion was prepared with chitosan(CS)solution as the water phase and PLA solution as the oil phase.PLA/CS@ZIF-8 nanofiber membranes with sustained drug release properties were modified by the secondary growth method which APS and camptothecin(CPT)were used as model drugs in this study.The morphologies and structures of composite nanofiber membranes were characterized using Scanning electron microscope(SEM),Fourier infrared spectrum(FT-IR),X-ray photoelectron spectroscopy(XPS)and Energy spectrometer(EDX),X-ray diffraction(XRD),Thermogravimetric analysis(TG),Truecolor confocal microscope and Water contact angle(WCA).The cumulative release curve was used to compare the release performance of APS and CPT with the composite nanofiber membranes and the kinetic model is used to study the release mechanism.The results showed that the drug loading and encapsulation rate of PLA@ZIF-8nanofiber membrane were 46.6% and 95%,respectively.As the incubation time prolonged and the 2-MIM concentration increased,the size of ZIF-8 increased and the distribution of ZIF-8 became more uniform,resulting in increased the hydrophilicity and surface roughness.With the increase of 2-MIM concentration,the content of ZIF-8 on the surface of PLA/CS@ZIF-8 nanofiber membrane increased and the drug loading and encapsulation rate were 35.7% and 93%,respectively.The APS cumulative release of PLA/CS@ZIF-8 nanofiber membranes was higher than that of CPT which showed that the release rate of APS was faster,and the release process was consistent with the Korsmeyer-Peppas model.The dissolution and diffusion of the ZIF-8 skeleton in an acidic solution resulted in a faster release in a mild acidic buffer solution,presenting excellent pH response during the process of drug release.The PLA@ZIF-8and PLA/CS@ZIF-8 nanofiber membranes have good pH response and can be used as new drug sustained-release carriers,providing new ideas and new methods for accurate treatment.