Antibacterial activity cationic polymers

Kanazawa A, Ikeda T, Endo T (1993) Polymeric phosphonium salts as a novel class of cationic biocides. III. Immobilization of phosphonium salts by surface photografting and antibacterial activity of the surface-treated polymer films. J Poly Sci A Poly Chem 31 1467-1472... 

To measure the antibacterial activities of amphiphilic cationic polynorbornene derivatives, they developed a slightly different method based on optical density (OD). In this method, bacteria were grown in suspensions (Escherichia coli D31 and Bacillus subtilis ATCC 8037 ) of Miieller-Hinton broth (MHB) overnight at 37 °C, diluted with fresh MHB to an OD of 0.1 at 600 nm and further diluted by a factor of 10. This suspension was mixed with different concentrations of freshly prepared polymer solutions in rm-buffered saline (pH 6.5-7.0), by serial dilution in a 96-well plate, and incubated for 6 h at 37 °C. The OD 600 nm was measured for bacteria suspensions that were incubated in the presence of a polymer solution or fm-buffered saline only. After 6 h, the MIC for 90% inhibition of growth was determined. 

Al-Badri and co-workers [55] studied the effect of fine-tuning the cationic parameter of synthetic mimics of antimicrobial peptides (SMAMP) on haemolytic and antibacterial activities. A category of novel norbornene monomers that carry one, two or three Boc-protected amine-functionalities was synthesised (Figure 3.8). ROMP of the monomers, followed by deprotection of the amine groups led to cationic antimicrobial polynorbornenes that carry one, two and three charges per monomer repeat unit. It was observed that enhancing the number of amine groups on the most hydrophobic polymer effectively decreased its haemolytic activity. 

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. 

Gao and co-workers investigated the random copolymers of acrylamide and vinyl pyridine, of varying MW and pyridine content, which were subsequently quaternised with dimethyl sulfate [22], Investigations proved that polymers with higher cationic functionality showed stronger antibacterial activity. In addition, depending on their alkyl chain length, methacrylate-based polymers with pendent pyridinium moieties were found to exhibit antibacterial activity [23]. 

Cationic polymer-functionalised gold NP have large concentrations of positive charge, which promote their adsorption onto negatively charged bacterial membranes via electrostatic interactions. This kind of antimicrobial material, with effective antibacterial activity and better biocompatibility, can promote the healing of microbially infected wounds and could have promising applications in the biomedical field. 

Fluorinated surfactants and polymers may have a therapeutic effect of their own. Sawada et al. [180-182] have prepared fluoroalkylated anionic [180,181] and cationic poly soaps [182], The fluoroalkylated acrylic acid co-oligomers containing dimethylsilicone segments [180] and fluoroalkylated 2-(methacry-loxy)ethanesulfonic acid oligomers [181] were found to function as inhibitors of HIV-1 virus replication. A fluoroalkylated 4-vinylpyridinium chloride-acrylic acid cooligomer exhibited both virus-inhibiting and antibacterial activities [182]. 

---