Evaluation of polyvinyl pyrrolidone nanofibers for encapsulation, protection, and release of curcumin: Impact on in vitro bioavailability

Despite exhibiting a range of potentially beneficial pharmacological effects, curcumin (Cur) currently has limited pharmacological application due to its low water solubility. Polymeric fibers can be used to encapsulate hydrophobic drugs with low water solubility and poor stability. In this study, the potential of polyvinyl pyrrolidone (PVP) electrospun fibers for Cur encapsulation was explored. First different solvents (ethanol, methanol, or isopropanol) were assessed for preparation of PVP fibers to determine proper concentration of polymeric solutions. To include Cur in PVP fiber acetone was used as cosolvent and varying Cur:PVP ratios (1:2, 1:4 1:6, 1:8 (w/w)) were examined to find out the best ratio. Then the effect of substitution of acetone with glacial acetic acid as cosolvent was studied. After selection of appropriate solvent/cosolvent system, solutions with varying Cur:PVP ratios (1:6, 1:8, 1:10 (w/w)) were examined for their viscosities, electrical conductivities and the morphology and physicochemical properties of the electrospun fibers. Interactions between the Cur and PVP in the fibers was assessed by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. Cur-loaded fibers with suitable properties could be formed from solutions containing PVP (10 % w/w) in ethanol or isopropanol or 15 % w/w PVP in methanol. The viscosity and conductivity of the fiber-forming solutions depended on their composition. All solutions except those prepared from isopropyl alcohol could produce suitable fibers. Scanning electron microscopy confirmed the uniform distribution of small fibers, revealing that their morphology and mechanical characteristics are related to the type of solvent used. Cur loading varied from 61 % to 86 %. Cur dissolution from all fibers was significantly faster than Cur powder, with 90 % being released within 10 to 15 min. FTIR analysis showed hydrogen bonding between Cur and PVP. DSC and XRD results suggested that Cur was in an amorphous form. This study showed that electrospun PVP fibers have great potential for increasing the dissolution rate of Cur.