Katherine Delgado

Polypropylene with embedded copper metal or copper oxide nanoparticles as a novel plastic antimicrobial agent

Aims:  To develop novel polypropylene composite materials with antimicrobial activity by adding different types of copper nanoparticles.

Toward Tailor-Made Biocide Materials Based on Poly(propylene)/Copper Nanoparticles

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.

Antimicrobial polymer composites with copper micro- and nanoparticles: Effect of particle size and polymer matrix

The 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 10 nm and 45 µm, 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.

Comportamiento antibacteriano de partículas de cobre frente a microorganismos obtenidos de úlceras crónicas infectadas y su relación con la resistencia a antimicrobianos de uso común.

BACKGROUND The antimicrobial activity of copper (Cu+2) is recognized and used as an antimicrobial agent. AIM To evaluate the antimicrobial activity of copper against microorganisms obtained from chronic cutaneous wound infections. MATERIAL AND METHODS Five chemical products that contained copper particles in their composition were tested (zeolite, silica, acetate, nitrate and nanoparticle of copper). The antimicrobial activity against antibiotic resistant strains usually isolated from chronic cutaneous wound infections was determined for two of the products with better performance in copper release. RESULTS The minimal inhibitory and minimal bactericidal concentrations of copper acetate and nitrate were similar, fluctuating between 400-2,000 µg/ml. CONCLUSIONS The studied copper salts show great potential to be used to control both gram positive and gram negative, antibiotic resistant bacteria isolated from wound infections.Background: The antimicrobial activity of copper (Cu+2) is recognized and it is used as an antimicrobial agent. Aim: To evaluate the antimicrobial activity of copper against microorganisms obtained from chronic cutaneous wound infections. Material and methods: Five chemical products that contained copper particles in their composition were tested (zeolite, silica, acetate, nitrate and nanoparticle of copper). The antimicrobial activity against antibiotic resistant strains usually isolated from chronic cutaneous wound infections was determined for two of the products with better performance in copper release. Results: The Minimal inhibitory and minimal bactericidal concentrations of copper acetate and nitrate were similar, fluctuating between 400-2,000 ?g/ml. Conclusions: The studied copper salts show great potential to be used to control both gram positive and gram negative, antibiotic resistant bacteria isolated from wound infections.

In situ antimicrobial behavior of materials having copper-based additives in a hospital environment

Copper and its alloys are effective antimicrobial surface materials in the laboratory and in clinical trials. Copper has been used in the healthcare setting to reduce environmental contamination, and thus prevent healthcare-associated infections, complementing traditional protocols. The addition of copper nanoparticles to polymer/plastic matrices can also produce antimicrobial materials, as confirmed under laboratory conditions. However, there is a lack of studies validating the antimicrobial effects of these nanocomposite materials in clinical trials. To satisfy this issue, plastic waiting room chairs with embedded metal copper nanoparticles, and metal hospital IV pools coated with an organic paint with nanostructured zeolite/copper particles were produced and tested in a hospital environment. These prototypes were sampled once weekly for 10 weeks and the viable microorganisms were analysed and compared with the copper-free materials. In the waiting rooms, chairs with copper reduced by around 73% the total viable microorganisms present, showing activity regardless of the microorganism tested. Although there were only low levels of microorganisms in the IV pools installed in operating rooms because of rigorous hygiene protocols, samples with copper presented lower total viable microorganisms than unfilled materials. Some results did not have statistical significance because of the low load of microorganisms; however, during at least three weeks the IV pools with copper had reduced levels of microorganisms by a statistically significant 50%. These findings show for the first time the feasibility of utilizing the antimicrobial property of copper by adding nanosized fillers to other materials in a hospital environment.

CHAPTER 13:Polymer/Copper-Based Materials for Antimicrobial Applications

Different metals and alloys containing copper have been largely used for antibacterial applications. During recent years, however, the use of copper particles embedded into a polymeric matrix has been stressed as allowing the development of novel plastic materials with controlled antimicrobial behavior. This chapter introduces the main concepts behind the strong biocide behavior of both copper and polymer/copper composite materials with a focus on nanoparticles. The state-of-the-art regarding polymeric composites based on copper is further discussed together with a general mechanism for the controlled ion release of these systems.