Fabrication of novel dual thermo- and pH-sensitive poly (N-isopropylacrylamide-N-methylolacrylamide-acrylic acid) electrospun ultrafine fibres for controlled drug release.

Dual temperature- and pH-sensitive materials used as drug carriers have attracted a particularly high level of interest. However, it is limited by low sensitivity to changes in conditions because of large size and low specific surface area. In this work, novel dual temperature- and pH-sensitive poly(N-isopropylacrylamide-N-methylolacrylamide acrylic acid) (PNIPAm-NMA-AAc) ultrafine fibres were successfully prepared by radical copolymerisation, electrospinning and thermal chemical treatment. The PNIPAm-NMA-AAc ultrafine fibres were characterized by Fourier transform infrared (FTIR), proton nuclear magnetic resonance (H NMR), spectroscopy UV-visible spectroscopy, scanning electron microscopy (SEM) and cell counting kit-8 (CCK-8) assay. The uniformity and small size of PNIPAm-NMA-AAc ultrafine fibres with LCST range from 31 °C to 43 °C were used to drug carrier because of good thermal stability, no cytotoxic. Curcumin as a model drug was well distributed in PNIPAm-NMA-AAc ultrafine fibres. In addition, analysis of curcumin release at different pH values and temperatures confirmed that the PNIPAm-NMA-AAc ultrafine fibres are responsive to both temperature and pH. The maximum amount of curcumin released was 98.47% ± 1.87%. In addition, the release mechanism of curcumin-based PNIPAm-NMA-AAc ultrafine fibres was shown to conform to Fickian diffusion (r ≥ 0.95). These results indicated that dual-responsive PNIPAm-NMA-AAc ultrafine fibres are promising as drug carriers.