Fabrication Of P(NVCL-co-MAA) Electronspun Nanofibers With PH/thermo Responsive Properties And Drug Release Behavior

Stimuli-responsive polymers can respond to external stimuli,such as pH,temperature or light,and then exhibit a promising prospects in biomedical fields.Recent years,poly(N-vinylcaprolactam)(PNVCL)is a well studied temperature-responsible polymer,which shows the lower critical solution temperature(LCST)close to the temperature of human body and a hydrophilic and hydrophobic transiton while below and above the LCST.Besides,as is non-toxic and biocompatible polymer,PNVCL is an ideal material for drug delivery.Electrospinning,as a convienent way for the fabrication of high specific surface area and small size micro/nanofibers,has been applicated in obtaining drug delivery vehicles.As far as we known,there are few studies of the fabrication of PNVCL copolymers electronspun nanofibers in drug delivery as morphology of the nanofibers couldn't be maintained in solution.In this work,PNVCL and pH/temperature sensitive polymers poly(N-vinylcaprol-alactam-co-methacrylicacid)(P(NVCL-co-MAA))with the mass ratio of 90/10,75/25,65/35 and 60/40 were synthesized via the radical polymerization.The copolymerizations of NVCL and hydrophilic acidic momomer MAA can adjust the LCST to 37 ?.FT-IR was used for structural characterization,indicating Hydrogen-Bonding interactions between NVCL and MAA in copolymer;The temperature-responsive properties of the nanofibers was detected by contact angle(CA).UV-vis spectra were used for LCST measurement;The LCST of P(NVCL-co-MAA)with the mass ratio of 90/10 in phosphate buffer saline(PBS)(pH=5.20,1.99)were adjusted to 36.4? and 36.3? respectively.Nanofibers composed of PNVCL and P(NVCL-co-MAA)were fabricated by the single-spinneret electrospinning technique and used as drug carriers by co-spinning with water insoluble drug NIF.Scanning electron microscopy(SEM)was used to demonstrated the morphology.The parameters of P(NVCL-co-MAA)/NIF with the mass ratio of 90/10 as followed: the concentration of P(NVCL-co-MAA)/DMF containing 4.2% NIF was 0.5 mg/mL;The flow rate of solution was set to be 0.9mL/h,and the applied voltage was 15 Kv.The tip-to-collector distance was 15 cm.Furthermore,a drop of water was placed on the surface of the nanofibers at 25? and45? to study the change on the morphology of the nanofibers after contact with water.PNVCL/NIF nanofibers dissovle in water,while the nanofibers of P(NVCL-co-MAA)/NIF with the mass ratio of 90/10 can maitain its morphology.Finally,the drug release behavior of P(NVCL-co-MAA)nanofibers with the mass ratio 90/10 in PBS was studied by adjusted the temperature at 37? and pH of 1.99.