Novel antimicrobial ultrathin structures of zein/chitosan blends obtained by electrospinning

This paper describes the formulation, morphology and biocide properties of novel antimicrobial electrospun zein based ultrathin fiber structures. From the results, it was found that the electrospun fibers of zein can turn the material into a new strong antimicrobial ultrathin-structured system due to retention of remnant amounts of trifluoroacetic acid as determined by ATR–FTIR spectroscopy. Unfortunately, this system may be considered to yield very aggressive high acidic media due to release of the strong acid, which causes the antimicrobial behavior. Nevertheless, since biocide properties are more desirable at mild acidic conditions, blending zein with the natural antimicrobial chitosan (up 10 wt.%) was found to be the route of choice to yield water insoluble fiber mats, with efficient biocide properties, attributed in this case not to the acid but to the chitosan component. Differential scanning calorimetry thermograms indicated that despite the fact that both components, as suggested by scanning electron microscopy observation, are not miscible, the presence of the chitosan phase leads to slightly enhanced glass transition temperature for the zein phase. Selective removal of chitosan from the blend indicated that this component is primarily present in beaded regions of the ultrathin fiber mats.