Mechanisms of Antimicrobial Polymers

Diffusion through the cell wall Strong Weak 

Reproduced with permission from E.R. Kenawy, S.D. Worley and R. Broughton, Biomacromolecules, 2007, 8,1359. 2007, American Chemical Society [9]  

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Formation and protective mechanisms of antimicrobial polymer coatings are in principal the same as in inhibited paint-and-varnish coats [97],... 

The problems of bio-functional polymers were diseussed on the 4 session. This session included 6 lectures. The speakers gave information about biofunctional dendritic architectures, biocompatible and bioactive polymers containing saccharide fimctionality, design and mechanisms of antimicrobial polymers, control of protein adsorption on functionalized electrospun fibers, microcapsules and nanoparticles for controlled delivery and repair, smart nanocarriers for bioseparation and responsive drug delivery systems. 

The interaction of the homopolymers of this series with biomimetic vesicles was examined by Gabriel et to understand the mechanism of antimicrobial activity and selectivity. Dye leakage of quenched calcein-filled vesicles was measured upon exposure to polymers of series C19. The vesicles consisted of 3 1 POPE POPG lipids to mimic the composition of E. coli membranes. Across the series, dye leakage correlated with... 

Antibiotic-resistant bacteria cause life-threatening infections in hospitals and society in general. There is a vital requirement to develop new antimicrobial agents, but this task involves extensive scientific trials. This chapter reviewed broad-spectrum polymeric antimicrobials, which are not susceptible to current resistance, and mechanisms of bacteria to mimic the antimicrobial action of natural HDP, which exert their effect by permeabilising the bacterial cytoplasmic membrane. Most cationic antimicrobial polymers appear to work in a manner similar to membrane-active AMP, such as magainin. The design and synthesis of different polymers, such as methacrylate-based copolymers, PPE, polynorbornene by-products, amphiphilc arylamide polymers and large polymers, have been studied as biomimetic polymers in different applications. 

In order to imnimise the risk of increasing antibiotic resistance associated with the use of antimicrobial devices, transition-metal-containing polyurethanes (PU) have been loaded with ciprofloxacin, which was chosen because it possesses a different mechanism of action [43]. In this way, the presence of two antibacterial agents in the polymer allows the development of an antimicrobial polymer whose activity is not limited by the increasing occurrence of antibiotic resistance. 

It has been reported that silver ion-exchanged zeolites exhibit antibacterial activity [32]. The mechanism of antibacterial action of the zeolite is initiated when moisture or liquid film comes into contact with the ion exchange material and silver ions are exchanged with sodium (Na) or other cations from the environment [33]. The released silver ions attach to the bacteria by forming chelate complexes with deoxyribonucleic acid, which blocks the transport processes in the cell [34]. The use of zeolite as a filler in polymeric materials has been reported in the literature and it has been proved that they enhance the antibacterial activity of the polymer [35]. Furthermore, the effect of zeolite content on the physical and thermal properties of the polymer was also examined [35] increasing the silver/zeolite ratio in the polymer led to an increased antimicrobial activity (due to the higher silver ion concentration), but depending upon the application the zeolite content may influence physical, thermal and/or chemical properties of the polymeric material. 

Hence, PP composites containing zinc oxide along with silver can further enhance the antimicrobial properties of this polymer. Antibacterial elastomer composites of silver zeolite/silicone could be a useful material to satisfy a range of requirements including good mechanical properties, due to the incorporation of zeolite, and good antibacterial properties. 

CS-metal/alumina complexed nanocomposites could be promising candidates for antimicrobial agents in the cosmetic, food and textile industries. Quaternised CS and CS-iodine could be future materials with enhanced biocidal properties. Improving our understanding of antimicrobial mechanisms will enable the continued design of new biocidal polymers, which is necessary in order to combat the development of microbial resistance. 

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