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

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).This work was supported by the Foundation for Science and Technology (FCT) and Portugal 2020 (projects PTDC/QUI-QIN/29697/2017, LISBOA-01-0145-FEDER-029697, UIDB/00100/2020, UIDP/00100/2020, IPL/2020/HyBioPol and REM2013), contracts CEECIND/02725/2018 and CEECIND/00194/2020.