Design And Fabrication Of Self-Powdered PVDF Based Electro-Responsive Drug Loaded Membrane

Electro-responsive drug delivery system is one of intelligent drug delivery systems,which is well-known for its rapid response,accurate drug release and stable structure.In recent years,it has been widely used in transdermal drug delivery,nerve repair,tumor therapy,etc.Its response mechanism mainly depends on the reversible oxidation（doping）and reduction（dedoping）reaction of intrinsic conductive polymer（ICP）.Different dopants can be selected according to the properties of the drug to attach and detach the drug.Among them,loading and releasing of anionic drugs by ICP has been widely reported.It can be directly used as the dopant of ICP,which is loaded at the oxidation potential and then released at the reduction potential.At present,most of the electrical stimulation of the electro-responsive drug delivery system needs external electrical stimulus with bulky equipment or external nano-generators,which is not easy to carry or has a complex structure,limiting the promotion and application of this kind of method to a certain extent.Therefore,a self-powered drug delivery system will greatly improve the treatment compliance for patients.However,the self-powered drug delivery systems reported is limited,which is the current hotspots and attractive trend.Therefore,a self-powered drug delivery system with integrated structure is designed in this thesis.The electrospinning PVDF/DA piezoelectric fiber membrane is prepared by blending the piezoelectric polymer polyvinylidene fluoride（PVDF）with dopamine（DA）.The interaction between PVDF and DA resulted in self-assembled core-shell fiber membrane,providing PVDF enhanced piezoelectric properties as well as abundant active sites on the fiber surface.It is beneficial to the subsequent in-situ grafting of conductive polymer poly（3-ethylenedioxythiophene）（PEDOT）.The anionic drug dexamethasone sodium phosphate（Dex）,which has a wide range of indications for anti-inflammation and anti-allergy,was loaded on the oxidation potential of PEDOT by constant voltage.Considering the possible application conditions,the controlled release of the fiber membrane was verified by the pressure of 1 Hz and the ultrasound of 40 k Hz respectively.The conclusions of this thesis are as follows:（1）Different surface morphology can be obtained by adjusting the electrospinning parameters of PVDF.When the fiber morphology is good,the fibers are randomly arranged,and when the film thickness is 40μm,the highest content ofβphase in the fiber membrane could be acquired,and the best piezoelectric properties can be obtained.Under the condition of 1 Hz,1 N and indenter with a diameter of 1 cm,the open circuit voltage is 0.80±0.22V.（2）The addition of DA in the spinning solution can promote crystallinity of theβphase of PVDF,and further improve the piezoelectric properties of the fiber membrane to 3.06±0.41 V.The anhydrous Fe Cl₃ ethanol solution was filtered onto the fiber membrane,and after chemical vapor deposition for 2 h,PEDOT was uniformly coated onto the fiber surface,and the R_Sdecreased from>20 MΩ/sq to 115.24±17.35Ω/sq.The polymerization process had no influence on the piezoelectric properties of the fiber membrane（3.35±1.39V）.（3）By applying 1 N vertical force with 1Hz on the drug delivery system,Dex can be released stably and continuously,and the cumulative release amount in 40 min was about 80%,which was similar to that of positive control（drug loaded through suction filtration）.Only about 30%of the Dex in 40min was released without external force.Under the stimulation of 40 k Hz high-frequency ultrasound,about 80%of Dex was released in 5 min and the cumulative release was about 90%at 40 min.Besides,the release curve was similar to that of the positive control.The results showed that the self-powered electro-responsive drug delivery system can control the drug release on demand.A self-powered intelligent drug delivery system is constructed,which provides a novel method and lays a theoretical foundation for clinical drug controlled release system.