Efficiency of silver‐based antibacterial additives and its influence in thermoplastic elastomers

Abstract

Styrene-butylene/ethylene-styrene-based thermoplastic elastomers (TPE) are polymers with soft touch properties that are widely used for manufacturing devices that involve hand contact. However, when contaminated with microorganisms these products can contribute to spreading diseases. The incorporation of antibacterial additives can help maintain low bacteria counts. This work evaluated the antibacterial action of TPE loaded with silver ions and silver nanoparticles. The additives nanosilver on fumed silica (NpAg_silica), silver phosphate glass (Ag 1 _phosphate), and bentonite organomodified with silver (Ag 1 _bentonite) were added to the TPE formulation. The compounds were evaluated for tensile and thermal properties and antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). All the additives eliminated over 90% of E. coli, but only NpAg_silica killed more than 80% of S. aureus population. The better effect of NpAg_silica was attributed to the additive's high specific surface area, which promoted greater contact with bacteria cells.

Synthesis and Effect of Hierarchically Structured Ag-ZnO Hybrid on the Surface Antibacterial Activity of a Propylene-Based Elastomer Blends

“…It can be explained by the difference in the cell wall structure. The thick peptidoglycan cell wall of Gram-positive bacteria protects its cell from silver penetration while Gramm-negative bacteria lack this protection [ 60 , 61 ]. Similar effect of the cell wall may apply for the case of Zn 2+ ions as well as for ROS action [ 56 , 57 , 62 ].…”

Silver effect on the biodegradation process of styrene-ethylene/butylene-styrene based thermoplastic elastomers compounds upon weathering exposure

“…In styrene-ethylene/butylene-styrene (SEBS)-based TPE matrices, the metal particles have the tendency to remain in the SEBS/oil phase (Tomacheski et al, 2016). The amorphous part of the polymer matrix is prone to oxidation; whereas the crystalline phase of the polymer is more susceptible to a molecular reorganization, such as chains fragmentation (Corti et al, 2010).…”

Biosynthesis and Functionalization of Bacterial Cellulose Membranes with Cerium Nitrate and Silver Nanoparticles

“…Generally, Gram-negative bacteria are more resistant to antibacterial agents than Gram-positive bacteria due to the complexity of the cell membrane of Gram-negative, which hinders the entry and, consequently, the diffusion of the AgNPs into these microorganisms 26 . Based on studies with individual strains from different cultures, Tomacheski et al 27 reported that S. aureus is more resistant to AgNPs in comparison to to E. coli. In this way, the authors showed that the bactericidal efficiency of the nanoparticles does not depend only on the structure of the bacterial membrane.…”

“…However, some mechanisms of toxicity are suggested: a) the contribution of free silver ions followed by disruption of ATP production and DNA replication (AgNPs act on the phosphate of DNA molecules resulting in the inactivation of their replication); b) formation of oxygen reactive species by the ions and AgNPs. These molecules react with the sulfhydryl -SH groups of the cell wall to form R-S-S-R blocking respiration, and causing cell death; c) direct damage of the cell membrane by AgNPs, affecting the permeability of the membrane 27 .…”