The antibacterial properties and toxicity of silver nanoparticles against microorganisms are well known and are therefore used in various types of formulations, such as surface coating agents, wound dressings, etc. Wound dressings containing silver nanoparticles use delivery systems that release silver in various concentrations. Various factors, such as the distribution of silver in the dressing, its chemical and physical form, the affinity of dressing to moisture also influence the destruction of microorganisms [15].

Hydrogels have become very popular due to their unique properties, such as high-water content (80-90%), flexibility and biocompatibility. Natural and synthetic hydrophilic polymers can be physically or chemically crosslinked to produce hydrogels. Their resemblance to living tissue offers opportunities for a wide range of biomedical applications. Currently, hydrogels are used for the manufacture of contact lenses, hygiene products, tissue engineering scaffolds, controlled drug delivery systems and wound dressings. There are a number of both natural: collagen, chitosan, alginate and synthetic polymers: polyvinyl alcohol (PVA), polylactic acid (PLA) which can serve as biomedical hydrogels [16], [17].

Studies have shown that silver nanoparticles in various shapes such as nanocubes, nanowires, nanospheres, and triangular nanoplates, can have a different antibacterial activity. Silver triangular nanoplates and nanospheres are the ones that presented the best antimicrobial activity against several microorganisms like Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus. This indicates that the antimicrobial activity of AgNPs depends on their morphology [3].

5. Conclusions and further perspectives