A new technology of microdispersed silver in polyurethane induces antimicrobial activity in central venous catheters

Abstract

Metal ions or metal ions in complexes or compounds have been used for centuries to disinfect fluids, solids and tissues. The biocidal effect of silver, with its broad spectrum of activity including bacterial, fungal and viral agents, is particularly well known and the term "oligodynamic activity" was coined for this phenomenon. Silver ions have an affinity to sulfhydryl groups in enzyme systems of the cell wall, through which they interfere with the transmembranous energy transfer and electron transport of bacterial microorganisms. Silver ions also block the respiratory chain of microorganisms reversibly in low concentrations and irreversibly in higher concentrations. Binding to the DNA of bacteria and fungi increases the stability of the bacterial double helix and thus inhibits proliferation. There is no cross resistance with antibiotics and also no induction of antimicrobial resistance by silver ions. The concentrations required for bactericidal activity are in the range 10(-9) mol/l. These concentrations can be achieved in solution by the interaction of metallic silver with electrolytes only if there is a large enough surface of silver. By a novel technology, metallic silver is distributed in submicron particles in polyurethane and results in a concentration of 0.8% in an active surface of 450 cm2/g polyurethane. Polyurethane is hygroscopic and rapidly attracts water; the interaction of electrolyte solutions with the extremely finely distributed silver throughout the polyurethane releases bactericidal concentrations of silver ions over a period of years to the surface of the material. The electronegatively charged surface of bacteria attracts the positively charged silver ions. The concentrations released from the polyurethane are far below the toxic concentrations for humans.

Antimicrobial activity of hemocompatible silver doped hydroxyapatite nanoparticles synthesized by modified sol–gel technique

“…It is also known to interfere with the trans-membrane electron transport, block respiratory chain at the cytochromes and cause metabolic flux inducing a proton leakage through the bacterial cell wall (Kim et al 1998;Klasen 2006). In comparison to other metals with antimicrobial properties, silver has the most effective antibacterial action and the least toxicity to animal cells (Guggenbichler et al 1999).…”

Production of putrescine-capped stable silver nanoparticle: its characterization and antibacterial activity against multidrug-resistant bacterial strains

“…This may be due to the presence of thick peptidoglycan layer in case of Gram-positive strains, which hinders the nanoparticle entry (Sondi and SalopekSondi 2004;Nabil et al 2000). But, here the positively charged capping of the polyamines might be valuable for binding with the teichoic acid groups and also the other negatively charged moieties present there, thus helping in the entry of nanoparticles (Guggenbichler et al 1999).…”

"ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES COATED INTRAVASCULAR CATHETERS (AgNPs-IVC) AGAINST BIOFILM PRODUCING PATHOGENS "

“…Antimicrobial activity of nanoparticles are well known, of all the nanoparticles, silver nanoparticles have been described as the one with the highest level of toxicity for microorganisms and lowest toxicity for animal cells. 10 The researcher reported that the plant extract assists synthesized AgNPs have recently appeared as new antimicrobial agents due to their high surface area to volume ration and unique chemical and physical properties. 11,12 The antibacterial activity AgNPs The improvement of impregnation of medical devices with silver nanoparticles is that it protects both outer and inner surfaces of medical devices and there is the continuous release of silver ions providing good antimicrobial activity.…”