Biopolymer films doped with silver(I) coordination polymers against bacterial biofilms

Abstract

This report describes a template-mediated self-assembly synthesis, full characterization, and structural features of two new silver-based bioactive coordination polymers (CPs) as well their immobilization into acrylated epoxidized soybean oil (ESOA) biopolymer films for antimicrobial applications. The 3D silver(I) CPs [Ag4(8-H2pma)2]n·4nH2O (1) and [Ag5(6-H0.5tma)2(H2O)4]n·2nH2O (2) were generated from AgNO3 and pyromellitic (H4pma) or trimesic (H3tma) acid, also using N,N-dimethylethanolamine (Hdmea) as a template. Both 1 and 2 feature the intricate 3D layer-pillared structures driven by distinct polycarboxylate blocks. Topological analysis revealed binodal nets with the flu and tcj/hc topology in 1 and 2, respectively. These CPs were used to create new hybrid materials, namely by doping the [ESOA]n biopolymer films with very low amounts of 1 and 2 (0.05, 0.1, and 0.5%). Their antimicrobial activity and ability to inhibit bacterial biofilm formation was investigated in detail against both Gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria. Both silver(I) coordination polymers and derived biopolymer films showed activity against all the tested bacteria in a concentration dependent manner. Compound 1 was far more active, especially in preventing biofilm formation, with mean bacterial load reductions ranging from 3.7 to 4.3 log against the four bacteria (99.99% bacterial eradication). Thus, the present study expands the antibiofilm applications of CP-doped biopolymers, offering new perspectives and promising results for the design of functional biomaterials (Scheme 1).