Modulation of initial burst and long term release from electrospun fibrous mats can be achieved by sandwiching the drug loaded mats between hydrophobic layers of fibrous polycaprolactone (PCL). Ibuprofen (IBU) loaded PCL fibrous mats (12% PCL-IBU) were sandwiched between fibrous polycaprolactone layers during the process of electrospinning, by varying the polymer concentrations (10% (w/v), 12% (w/v)) and volume of coat (1 ml, 2 ml) in flanking layers. Consequently, 12% PCL-IBU (without sandwich layer) showed burst release of 66.43% on day 1 and cumulative release (%) of 86.08% at the end of 62 days. Whereas, sandwich groups, especially 12% PCLSW-1 & 2 (sandwich layers—1 ml and 2 ml of 12% PCL) showed controlled initial burst and cumulative (%) release compared to 12% PCL-IBU. Moreover, crystallinity (%) and hydrophobicity of the sandwich models imparted control on ibuprofen release from fibrous mats. Further, assay for cytotoxicity and scanning electron microscopic images of cell seeded mats after 5 days showed the mats were not cytotoxic. Nuclear Magnetic Resonance spectroscopic analysis revealed weak interaction between ibuprofen and PCL in nanofibers which favors the release of ibuprofen. These data imply that concentration and volume of coat in flanking layer imparts tighter control on initial burst and long term release of ibuprofen.

Summary Emeraldine salt of polyaniline‐coated copper substrate was used as a cathode to study hydrogen evolution reaction in 1M H2SO4. Hydrogen evolution reaction in acidic medium followed Grotthus mechanism, where proton hops randomly on the surface of polyaniline. With Randles‐Sevcik equation, the average value of diffusion coefficient for H+ on polyaniline was calculated to be 2.66 times higher than that in the literature data. This higher value explicitly supported the rapid diffusion of H+ on polyaniline surface from the bulk electrolyte solution. With the help of a phenomenological thermodynamic approach demonstrated elsewhere, the solvent‐modified work function of polyaniline‐coated copper in acidic medium was calculated. The plot of exchange current density versus solvent‐modified work function of different metals and polyaniline‐coated copper indicated that at lower work function polyaniline‐coated copper showed higher exchange current density and the rate of hydrogen evolution was much higher on polyaniline‐coated copper than on copper. This was further confirmed by gas chromatography, and 13C and 1H nuclear magnetic resonance studies supported the mechanism proposed. From linear sweep voltammetry analysis, it was observed that the total capacity of hydrogen stored on polyaniline‐coated copper was approximately 1.85 times higher than that on copper.

No abstract

No abstract

No abstract