| The electrospinning technique is a versatile method to prepare continuous nanofibers. These nanofibers all with large surface areas, high porosity and fine structure compared with any other known form of the spin technique. Due to their intrinsic features, electrospinning nanofibers are extensively applied in biomedical and biotechnological fields such as controlled drug delivery, tissue engineering and wound dressings. As a natural polymer, chitosan (CS) having attractive biocompatibility, biodegradability, nontoxic and its structure is sponge -like. CS could be used as matrix for controlled drug delivery to control the rate of drug delivery and prolong the release time of drugs, improve drug solubility, absorption and orientation, reduce the systemic side-effects. Polyvinyl-pyrrolidone (PVP) is one of the important pharmaceutical intermediates, which can form hydrogen bonds between the carbonyl group of PVP and the amino group of CS, while the ability of CS itself to form hydrogen bonds is reduced, so that it can improve the electrospun ability of CS as well as increase the mechanical strength of single fiber. At the same time, PVP can improve the dissolution of poorly water-soluble drugs because of the hydrogen bonding between PVP and drug molecules. Adding PVP in CS precursor solution improved the electrospun ability of CS solutions, studied the sustained release properties with CS/PVP composite nanofiber membrane containing buprofen (IBU) as model drugs.CS/PVP composite nanofibers were prepared by electrospinning, the optimal mass ratio of CS/PVP and other electrospinning parameters were discussed. SEM was used to study the morphology and average diameter of the CS/PVP composite nanofibers. The interaction between CS and PVP was analysed via FTIR and XRD. The tensile strength of the composite nanofibers was tested by single fiber strength tester. SEM images indicated that the composite nanofibers morphology are better when CS/PVP mass ratio was 20/80, electrospinning voltage was 18kV, distance was 12 cm and velocity was 0.2mL/h. FT-IR and X-ray diffraction spectra indicated that PVP and CS molecules form hydrogen bonds in the composite nanofibrous membrane. Mechanical tests showed that the tensile strength of the composite fiber membrane increased with increasing the content of CS, it is 19.87 MPa when the content of CS reaches to 40%, the elongation at break of the composite nanofibrous membrane decreased with increasing the content of CS.In this study, Ibuprofen (IBU) was loaded into the CS/PVP electrospun composite nanofibers, and SEM was used to study the morphology and average diameter of the drug loaded nanofibers. The chemical composition of drug loaded nanofibers were characterized by FTIR, the distribution state of IBU was detected via XRD. The tensile strength of the drug loaded nanofibers was tested by single fiber strength tester. The SEM images indicated that increasing IBU concentrations led to a decrease in average diameters of the composite fibers. FTIR suggested that new hydrogen bonds generated between IBU and nanofibrous matrix. XRD studies showed that IBU was in an "amorphous state" in electrospining nanofibrous matrix, While IBU from separating crystals out off from the casting membrane matrix. Mechanical tests showed that the tensile strength of the drug-loaded nanofibers membrane was first increases and then decreases with increasing the content of IBU.The release of the IBU from CS/PVP nanofibrous membrane was tested by UV-Visible spectrophotometer. It was observed that the CS/PVP nanofibrous membrane provided a slower release of the IBU compaired with CS/PVP casting membrane. The pure drugs finished release within four hours, the cumulative drug release percentage of drug loaded CS/PVP casting membrane is over 95%, whereas the cumulative drug release percentage of drug loaded CS/PVP nanofibrous is from 70 to 85 percent. The release rate of drug loaded CS/PVP nanofibrous increasd with increasing the content of CS as well as IBU. |
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