Novel PNIPAm-based electrospun nanofibres used directly as a drug carrier for "on-off" switchable drug release.

Stimuli-responsive smart polymers have been studied extensively. In this work, thermoresponsive poly (N-isopropylacrylamide-N-methylolacrylamide-acrylamide) (PNIPAm-NMA-Am) was successfully synthesised via radical polymerisation, as confirmed by proton nuclear magnetic resonance and fourier transform infrared spectroscopy. PNIPAm-NMA-Am was electrospun into nanofibres, allowing its use as a drug carrier after simple thermal treatment. Thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy results also revealed that the as-prepared PNIPAm-NMA-Am nanofibres have a uniform small diameter, good thermal stability and excellent integrity in aqueous environments. Additionally, the properties of this PNIPAm-NMA-Am nanofibres were tunable with temperature changes below and above the lower critical solution temperature of 48 °C. The drug release properties of PNIPAm-NMA-Am10 nanofibres as a drug carrier were studied via ultraviolet-visible spectroscopy and the results showed that 80% of the drug was released from the nanofibres after six heating and cooling (60-10 °C) cycles within 60 min. Only a small amount of the drug was released during the cooling process, which directly demonstrates "on-off" functionality of PNIPAm-NMA-Am nanofibres for controlled drug release. Finally, cell culture studies indicated that the PNIPAm-NMA-Am nanofibres have not cytotoxicity. Thus, the novel PNIPAm-NMA-Am nanofibres show great potential in the biomedical field as drug carriers.