Smart and in-situ formation electrospun fibrous membrane for the control of antimicrobial efficacy

Abstract

Abstract A smart poly(N-isopropyl acrylamide- N-Methylol acrylamide-acrylic acid) (PNIPAm-NMA-Ac) fibrous membrane with a dual response to thermal and pH was obtained via radical copolymerization and electrospinning technology. Two antimicrobial agents, gatifloxacin hydrochloride (GH) and silver nanoparticles (Ag) were chosen and incorporated into the PNIPAm-NMA-Ac fibres with different methods to achieve controllable antimicrobial efficacy with time. GH was directly mixed and Ag was in-situ formed to fabricate the antimicrobial membrane. The low water vapor transmission rate (23419.4 ± 2 5. 8 g/m2·24h), high water-contact angles (118 ± 1.1°), excellent mechanical properties (tensile strength, 2.09 ± 0.53 MPa; elongation at break, 20.18 ± 1.07 %), and good biocompatibility made the membrane have a great advantage on antimicrobial material. More importantly, both GH and Ag max release amounts are higher at 37 °C or pH 4.0 than 20 °C or pH 10.0 due to the smart thermal and pH responsive PNIPAm-NMA-Ac polymer. Meanwhile, GH and Ag release behavior are different: GH showed burst release behavior (72.72 ± 0.8 % for 40 mins), and Ag showed sustained release behavior (64.43 ±2.53 % for 3 h), which caused by the synergistic effect of two antimicrobial agents. Hence, antibacterial activity of this membrane is controllable with the environment temperature, pH value, and time. According to these results, this smart membrane has better antimicrobial efficacy at higher temperatures, lower pH and/or shorter time. In summary, this smart membrane could control the antimicrobial efficacy and be a potential membrane in harsh conditions.