Antibacterial activity induction into superabsorbent hydrogel via Schiff-base-metal coordination modification

As commercial superabsorbent polymer (SAP) hydrogels do not possess antimicrobial activity, the bioactivity induction is a research target to increase their diverse benefits, particularly, in their bio-applications. This work reports a facile and nearly quantitative synthesis of a novel partially bio-based Schiff base modifier (an imine-amine modifying agent based on furfural) under catalyst-free and solvent-free conditions. The modifier was identified by FTIR, 1 H- and 13 C-NMR spectroscopies. Then, a commercial SAP was feasibly surface modified by the modifier via a facile transamidation process followed by additional modification with copper (II) acetate to form Cu-coordination complex on the gel network ( A i : intact SAP, A 1 : modified with Schiff base, A 2 : modified with coordination complex, and A 3 : modified with copper (II) acetate). The modification reactions were confirmed morphologically and rheologically. The free-swelling measurements in deionized water and saline media revealed that the super absorbency was well-preserved after the modification. The saline-absorbency under load (AUL, 0.3 psi) tests verified that the modified samples owned 5–17% higher AUL compared to the unmodified sample. Antibacterial measurements against two bacterial strains ( S. aureus and E. coli ) proved that the metal complex formation significantly induces antibacterial activity comparing to both the intact and the metal-free Schiff-base-treated SAPs. The feasible processes and/or modified products may be considered for being used in bio-medical applications such as surgical pads and wound dressings.