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- Silver(I) coordination polymers immobilized into biopolymer films for antimicrobial applicationsPublication . Fernandes, Tiago; Costa, Inês F. M.; Jorge, Paula; Sousa, Ana Catarina; André, Vânia; Cerca, N.; Kirillov, Alexander M.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 [Ag-4(mu(8)-H(2)pma)(2)](n)center dot 4nH(2)O (1) and [Ag-5(mu(6)-H(0.5)tma)(2)(H2O)(4)] (n)center dot 2nH(2)O (2) were generated from AgNO3 and pyromellitic (H(4)pma) or trimesic (H(3)tma) 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.
- Hybrid silver(I)-doped soybean oil and potato starch biopolymer films to combat bacterial biofilmsPublication . Fernandes, Tiago; Costa, Inês F. M.; Jorge, Paulo; Sousa, Ana Catarina; Andre, Vania; Cabral, Rafaela G.; Cerca, N.; Kirillov, Alexander M.This study describes the preparation, characterization, and antimicrobial properties of novel hybrid biopolymer materials doped with bioactive silver(I) coordination polymers (bioCPs). Two new bioCPs, [Ag2(μ6-hfa)]n (1) and [Ag2(μ4-nda)(H2O)2]n (2), were assembled from Ag2O and homophthalic (H2hfa) or 2,6-naphthalenedicarboxylic (H2nda) acids as unexplored building blocks. Their structures feature 2D metal–organic and supramolecular networks with 3,6L64 or sql topology. Both compounds act as active antimicrobial agents for producing bioCP-doped biopolymer films based on epoxidized soybean oil acrylate (SBO) or potato starch (PS) as model biopolymer materials with a different rate of degradability and silver release. BioCPs and their hybrid biopolymer films (1@[SBO]n, 2@[SBO]n, 1@[PS]n, and 2@[PS]n) with a very low loading of coordination polymer (0.05–0.5 wt %) show remarkable antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis (Gram-positive) and Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacteria. Biopolymer films also effectively impair the formation of bacterial biofilms, allowing total biofilm inhibition in several cases. By reporting on new bioCPs and biopolymer films obtained from renewable biofeedstocks (soybean oil and PS), this study blends highly important research directions and widens a limited antimicrobial application of bioCPs and derived functional materials. This research thus opens up the perspectives for designing hybrid biopolymer films with outstanding bioactivity against bacterial biofilms.
- Etchability dependence of InOx and ITO thin films by plasma enhanced reactive termal evaporation on structural properties and deposition conditionsPublication . Amaral, Ana; Lavareda, Guilherme; Carvalho, Carlos Nunes de; Andre, Vania; Vygranenko, Yuri; Fernandes, Miguel; Brogueira, PedroIndium oxide (InOx) and indium tin oxide (ITO) thin films were deposited on glass substrates by plasma enhanced reactive thermal evaporation (PERTE) at different substrate temperatures. The films were then submitted to two etching solutions with different chemical reactivity: i) HNO3 (6%), at room temperature; ii) HCl (35%): (40 °Be) FeCl3 (1:1), at 40 °C. The dependence of the etchability of the films on the structural and deposition conditions is discussed. Previously to etching, structural characterization was made. X-ray diffraction showed the appearance of a peak around 2θ=31° as the deposition temperature increases from room temperature to 190 °C, both for ITO and InOx. AFM surface topography and SEM micrographs of the deposited films are consistent with the structural properties suggested by X-ray spectra: as the deposition temperature increases, the surface changes from a finely grained structure to a material with a larger-sized grain or/and agglomerate structure of the order of 250-300 nm. The roughness Rq varies from 0.74 nm for the amorphous tissue to a maximum of 10.83 nm for the sample with the biggest crystalline grains. Raman spectra are also presented.