Chitosan/heparin blends in ionic liquid produce polyelectrolyte complexes that quickly adsorb citrate-capped silver nanoparticles, forming bactericidal composites

Abstract

We present chitosan (CHT)/heparin (HP) polyelectrolyte complexes (PECs) that quickly adsorb citrate-capped silver nanoparticles (AgNPs). CHT/HP blends in ionic liquid ([HMIm][HSO4]) form durable PECs after precipitation in water. CHT/HP PECs have positive Zeta potentials (higher than +20 mV). They adsorb citrate-capped AgNPs (Zeta potential of - 12.25 mV) synthesized from Turkevich's method. PEC/AgNPs composites are characterized by spectroscopic, thermal, and microscopy analyses. AgNPs on the PEC surfaces are confirmed by transmission electron microscopy. PECs adsorb AgNPs from aqueous suspensions, achieving ≈ 95% of removal (17.18 μg of AgNPs per milligram of PEC) after only 10 min. The pseudo-second-order kinetic model adjusted well to the experimental data. The PECs release approximately 11.80 μg/mg Ag+ (66%) compared to the initial adsorbed AgNPs content (17.18 μg/mg) after 7200 min at pH 2.0. The PECs present low swelling degrees (between 130 and 150%), supporting high stability in water. PEC/AgNPs composites promote significant bactericidal activity toward Staphylococcus aureus and Escherichia coli between 0.25 and 0.5 mg/mL. This study shows a new strategy to create hybrid polysaccharide/AgNPs composites. PECs can stabilize the AgNPs and release Ag+ ions, supporting antimicrobial materials.