Disruption and Activation of Blood Platelets in Contact with an Antimicrobial Composite Coating Consisting of a Pyridinium Polymer and AgBr Nanoparticles

Abstract

Composite materials made up from a pyridinium polymer matrix and silver bromide nanoparticles embedded therein feature excellent antimicrobial properties. Most probably, the antimicrobial activity is related to the membrane-disrupting effect of both the polymer matrix and Ag(+) ions; both may work synergistically. One of the most important applications of antimicrobial materials would be their use as surface coatings for percutaneous (skin-penetrating) catheters, such as central venous catheters (CVCs). These are commonly used in critical care, and serious complications due to bacterial infection occur frequently. This study aimed at examining the possible effects of a highly antimicrobial pyridinium polymer/AgBr composite on the blood coagulation system, i.e., (i) on the coagulation cascade, leading to the formation of thrombin and a fibrin cross-linked network, and (ii) on blood platelets. Evidently, pyridinium/AgBr composites could not qualify as coatings for CVCs if they trigger blood coagulation. Using a highly antimicrobial composite of poly(4-vinylpyridine)-co-poly(4-vinyl-N-hexylpyridinium bromide) (NPVP) and AgBr nanoparticles as a thin adherent surface coating on Tygon elastomer tubes, it was found that contacting blood platelets rapidly acquire a highly activated state, after which they become substantially disrupted. This implies that NPVP/AgBr is by no means blood-compatible. This disqualifies the material for use as a CVC coating. This information, combined with earlier findings on the hemolytic effects (i.e., disruption of contacting red blood cells) of similar materials, implies that this class of antimicrobial materials affects not only bacteria but also mammalian cells. This would render them more useful outside the biomedical field.

New Strategies in the Development of Antimicrobial Coatings: The Example of Increasing Usage of Silver and Silver Nanoparticles

“…Upon a more careful examination of the adhered platelets, their morphology appeared distorted which indicated activation and disruption. This was in accordance with an earlier report by the same authors that described activation and disruption of platelets on surfaces containing AgBr nanoparticles [146]. The authors proposed that platelets may get activated and disrupted by mechanisms similar to the bactericidal effect of the silver nanoparticles.…”

The biocompatibility and biofilm resistance of implant coatings based on hydrophilic polymer brushes conjugated with antimicrobial peptides

“…4A), and also did not result in significant platelet adhesion compared to unmodified Ti-wire as evidenced by a scanning electron microscopy (SEM) analysis ( Figure 6S supplementary information). This was in contrast to previous investigations of polycat ionic polymer based antimicrobial surfaces [19]. The complement activation in human serum was investigated using a modified CH50 analysis [39].…”

“…A lack of hemocompatibility (highly relevant to vascular implants) and increased mammalian cell toxicity were major reasons for the poor performance of previously tested poly cationic as well as some silver-based antimicrobial coatings on implants [7,14,19]. Given the excellent non-specific protein/cell resistant properties of hydrophilic polymer brushes [27,38], we anticipated that the AMP immobilized copolymer brush coating would be non-toxic.…”

“…Further, suboptimal exposure of antibiotics can promote the development of drug resistant phenotypes [9e12] and enhance biofilm formation [13]. Despite the fact that localized antimicrobial delivery through implant coatings is a promising approach [7,14e18], it is often beleaguered by the poor biocompatibility of such coatings [14,19]. Alternative, noncovalent coatings have the disadvantage of developing a concentration gradient from the implant surface, such that bacteria can respond to the antibiotic leading to the development of drug resistance [10,12].…”

Antimicrobial and Anti‐Inflammatory Intelligent Surfaces

“…It has also been shown that a thin coating of an antimicrobial composite of poly(4 -vinylpyridine) -copoly(vinyl -N -hexylpyridinium bromide) and AgBr nanoparticles on Tygon elastomer tubes caused disruption and activation of blood platelets, making this coating unsuitable for blood -contacting devices applications. 55 It was, however, not clear whether it is the cationic copolymer or the Ag + ions, or both, that caused the adverse effects. In addition, another study found that the extent of adverse effects from silver ions differed for different cell lines, 56 which may help explain the inconsistencies in the literature where studies using only one cell line each, and different lines in different studies, have reported confl icting fi ndings.…”