Summary
Aims: To develop novel polypropylene composite materials with antimicrobial activity by adding different types of copper nanoparticles.
Methods and Results: Copper metal (CuP) and copper oxide nanoparticles (CuOP) were embedded in a polypropylene (PP) matrix. These composites present strong antimicrobial behaviour against E. coli that depends on the contact time between the sample and the bacteria. After just 4 h of contact, these samples are able to kill more than 95% of the bacteria. CuOP fillers are much more effective eliminating bacteria than CuP fillers, showing that the antimicrobial property further depends on the type of copper particle. Cu2+ released from the bulk of the composite is responsible for this behaviour. Moreover, PP/CuOP composites present a higher release rate than PP/CuP composites in a short time, explaining the antimicrobial tendency.
Conclusions: Polypropylene composites based on copper nanoparticles can kill E. coli bacteria depending on the release rate of Cu2+ from the bulk of the material. CuOP are more effective as antimicrobial filler than CuP.
Significance and Impact of the Study: Our findings open up novel applications of these ion‐copper‐delivery plastic materials based on PP with embedded copper nanoparticles with great potential as antimicrobial agents.
A set of poly(propylene) composites containing different amounts of copper nanoparticles (CNP) were prepared by the melt mixed method and their antimicrobial behavior was quantitatively studied. The time needed to reduce the bacteria to 50% dropped to half with only 1 v/v % of CNP, compared to the polymer without CNP. After 4 h, this composite killed more than 99.9% of the bacteria. The biocide kinetics can be controlled by the nanofiller content; composites with CNP concentrations higher than 10 v/v % eliminated 99% of the bacteria in less than 2 h. X-ray photoelectron spectroscopy did not detect CNP at the surface, therefore the biocide behavior was attributed to copper in the bulk of the composite.
Artículo de publicación ISIThe addition of metal particles, for instance, silver or copper, into polymer matrices is a relevant strategy producing novel antimicrobial materials. By using two particles with diameters around 10nm and 45 mu m, and polymers with different characteristics, the effect of filler size and matrix on the biocide behavior of polymer/copper composites was studied. The composites were prepared by melt mixing, and the ion release from these materials was used to obtain critical information about the processes involved. Regarding the effect of the particle size, our results for polypropylene showed that this variable drastically changes the release of copper from the matrix. The ion release rate from nanocomposites increased quickly exhibiting a sharp maximum during the first day; meanwhile, in microcomposites, the release rate increased slowly releasing lower ions. The relevance of particle size was confirmed by the antibacterial behavior of the samples as polypropylene with nanoparticles displayed larger activities against Staphylococcus aureus and Pseudomonas aeruginosa bacteria than microcomposites. These results further showed the relationship between copper ion release and antimicrobial behavior in polymer/metal composites. Our findings further revealed that the ion release from polymer composites could be improved by either increasing the hydrophilic characteristic of the matrix or by lowering its crystallinity. These observations allowed the conclusion that both the polymeric matrix and the size of the metal filler are relevant variables toward the design of antimicrobial composite materials.FONDECYT 111007
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