Polyethylene materials with multifunctional surface properties by electrospraying chitosan/vitamin E formulation destined to biomedical and food packaging applications

A dual-bioactive layer based on antimicrobial chitosan and antioxidant vitamin E was immobilized onto PE surface using electrospraying as coating technique. Covalent bonding of the antibacterial/antioxidant layer was achieved through amide bonds or carbamate linkage using both 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride and N-hydroxysuccinimide or carbonyldiimidazole coupling agents, respectively. The chitosan/vitamin E formulation was characterized by rheological measurements. The vitamin E addition in chitosan matrix leads to changes in chitosan rheological properties, such as viscosity decrease with increasing vitamin E content, change of the gel-like behavior to a fluid-like behavior, which further influences the electrospraying process and deposited coating morphology. The new stratified hybrid materials with improved properties have been characterized by different techniques as attenuated total reflectance-Fourier transform IR spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), polyelectrolyte and potentiometric titration, contact angle titration, scanning electron microscopy (SEM) and antibacterial and antioxidative tests. The electrosprayed bioactive coatings exhibit antibacterial, antioxidant and pH responsive activity. The pH responsiveness was evidenced by switching from hydrophilic to hydrophobic surface at pH approximate to 6. The chitosan/vitamin E modified PE substrate inhibited the growth for three different bacterial strains (Gram-negative and Gram-positive) and presented good antioxidative properties, acting as DPPH radical scavenging surfaces. Moreover, the new obtained materials present good stability and maintain their antioxidative capacity even after subjecting to desorption in harsh medium because of relative strong electrostatic and hydrogen bonds interactions between components of the formulation. The obtained materials can find application in food packaging or in medical field where synergistic action of these bioactive compounds is required.