Composite filter with antimicrobial and anti-adhesive properties based on electrospun poly(butylene adipate-co-terephthalate)/poly(acid lactic)/Tween 20 fibers associated with silver nanoparticles

Abstract

Ecovio® is a hydrophobic, biodegradable, and synthetic polymer blend composed of poly(butylene adipate-co-terephthalate) and poly(acid lactic) polyesters. It is soluble in solvents of low polarity, being a challenge to obtaining thin and homogeneous electrospun Ecovio® fibers. Ecovio® blend solutions do not have electrospinnability due to the low viscosity and electrical conductivity. For overcoming this disadvantage, Ecovio® and Tween 20 were associated with a binary 85/15 chloroform/formic acid mixture. The formic acid (15 vol%) and Tween 20 (1.0 v% concerning the total solution volume) increased the Ecovio® electrospinnability, promoting thin fibers (average diameter of 253 nm). Tween 20 (1.0% v/v) reduced the surface tension from 29.50 to 28.92 mN/cm and increased the electrical conductivity and viscosity from 0.85 to 2.03 μS/cm and 26.02–27.13 mPa s. The solution parameters were adjusted, imparting Ecovio® solution electrospinnability. The Tween 20 induced a wettable fiber surface that immediately absorbed a water droplet after contact, reducing the water contact angle from 125° on Ecovio® fiber (488 nm) to 0° on Ecovio®/Tween 20 fiber (253 nm). The wettable Ecovio®/Tween 20 fiber adsorbed silver ions (Ag+) from an aqueous solution, promoting a reinforced (Elastic modulus of 2136 MPa) and wettable composite fiber after Ag + reduction. The determined Ag0 content was 8 μg per composite fiber gram. Ecovio®/Tween 20 fibers stabilized the AgNPs, imparting anti-adhesive and antimicrobial properties against Staphylococcus aureus (S. aureus) and Escherichia coli. The composite filter removed bacteria from water (S. aureus at 107 CFU/mL), reaching a removal efficiency of 99.99% in the first filtration. The biodegradable and antimicrobial composite filter can replace conventional harsh chemicals that treat water, including drinking water contaminated with bacteria.