Electrospun poly(N-isopropylacrylamide)/poly(caprolactone)-based polyurethane nanofibers as drug carriers and temperature-controlled release

Electrospun micro- and nanofibers are being increasingly investigated for drug delivery. The components and stimuli-responsive properties of the fibers are important factors influencing the drug release behavior. The aim of this study was to fabricate thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm)/polyurethane (PU) nanofibers using a single-spinneret electrospinning technique. The electrospun nanofibers were used as drug carriers by co-spinning with nifedipine (NIF) and the release behavior of NIF can be controlled by the response of the nanofibers to temperature. The morphologies of the nanofibers and the composites with NIF were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The interactions between PNIPAAm and PU and the existence of the water-insoluble drug NIF were introduced and confirmed by Fourier-transform infrared spectroscopy (FTIR). The thermo-responsive behavior of the nanofibers was detected by contact angle (CA) measurements. Mechanical properties were analyzed by tensile test and the release behavior of NIF from the PNIPAAm/PU nanofibers was observed by SEM and demonstrated by UV-vis spectroscopy. It was found that uniform fibers of NIF and PNIPAAm/PU could be fabricated without the appearance of particles on the surface. The release of NIF from the nanofibers could be controlled effectively by adjusting the temperature of the environment surrounding the thermo-responsive nanofibers.