Hydrophilicity of electrospun microfibers of polyethylene oxide with semisoluble polyaniline for biological applications

This work studies the hydrophilicity of electrospun microfibers of polyaniline (PANI) synthesized by plasma combined with polyethylene oxide (PEO). The hydrophilicity was evaluated measuring the contact angles of water, phosphate‐buffered saline (PBS) and Krebs‐Ringer (KR) biological solutions formed on the polymers. Plasma PANI is usually insoluble due to the crosslinking associated with the electrical discharges of the synthesis conditions; however, PANI was synthesized as semi‐soluble films, which were dissolved and mixed with soluble PEO to obtain PANI/PEO electrospun microfibers. Super‐hydrophilic (90°) angles were obtained with the PBS solution on PANI/PEO fibers. PANI films had contact angles, which increased with the salts of KR and PBS solutions, PEO films had sudden increments and reductions with the saline solutions. PANI showed the typical chemical groups of polyanilines and others as CN and CC associated with a high dehydrogenation, which disappeared in PANI fibers. Electromagnetic absorption peaks in the 270–320 nm wavelength range were detected in the fibers and not in the films, which can be associated with transitions between benzoid and quinoid PANI structures. These results indicated that PANI/PEO fibers would not dissolve as rapidly as PEO fibers in biological solutions. Hydrophilicity is important in biomaterials as it is an indicator of their wettability, which is an essential characteristic to interact with the living tissues. The plot shows the contact angles of PANI, PEO, and PANI/PEO films and fibers with water, Krebs‐ringer, and phosphate‐buffered saline solutions. Note the great difference in the angles between PEO films and fibers (red lines).