Silver(I) Coordination Polymers Immobilized into Biopolymer Films for Antimicrobial Applications

This study describes a template-mediated
self-assembly synthesis,
full characterization, and structural features of two new silver-based
bioactive coordination polymers (CPs) and their immobilization into
acrylated epoxidized soybean oil (ESOA) biopolymer films for antimicrobial
applications. The 3D silver­(I) CPs [Ag4(μ8-H2pma)2]n·4nH2O (1) and [Ag5(μ6-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 for fabricating 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 impair bacterial biofilm formation were investigated in
detail against both Gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) and Gram-negative
(Pseudomonas aeruginosa and Escherichia coli) bacteria. Both silver­(I) CPs and
derived biopolymer films showed activity against all the tested bacteria
in a concentration-dependent manner. Compound 1 exhibited
a more pronounced activity, especially in preventing biofilm growth,
with mean bacterial load reductions ranging from 3.7 to 4.3 log against
the four bacteria (99.99% bacterial eradication). The present work
thus opens up antibiofilm applications of CP-doped biopolymers, providing
new perspectives and very promising results for the design of functional
biomaterials.