Antimicrobial plastic composites: what are they and how do they work?
People are exposed to a variety of bacteria and fungi throughout the day, in the normal course of going to work or school, running errands, going outside, eating, and general activities. Many of these microorganisms are harmless, but there are a select few that pose serious health concerns. Many technologies have been developed over the course of human history to combat the spread of these harmful microbes, and this work continues today as micro-organisms remain a challenge to public health in a few specific cases. From antibacterial soap or sprays to engineered plastic barrier films for food storage. Antimicrobial technologies are an important tool in maintaining our health and preventing the progression of disease. We would like to help provide an overview of some aspects of these technologies, and how they apply to our product family.
At NYCOA, our interest in antimicrobials is primarily in chemistries and additives able to produce efficacy as an additive to our engineered polyamide chemistry. One such area of recent focus has been the development of inherently antimicrobial plastic compounds, mostly based on copper and silver metals.
The antimicrobial properties of silver and copper have been known since ancient times, with ancient civilizations known to use copper and silver pots to safely store water and wine. Copper is believed to kill microbes by one of a few mechanisms that generate free hydroxyl radicals and by replacing other transition metals in important proteins (Grass, Rensing, & Solioz, 2011). The hydroxyl radicals generated in the cells of microbes vulnerable to copper exposure are incredibly reactive and destroy important proteins in the cell. Copper ions in the cells of these microbes are also able to block important binding sites or switch for other metals in important chemical structures, keeping these sites and structures from doing their jobs properly which leads to cell death.
Silver kills microbes by preventing the replication of DNA, which prevents the ribosomes within the cell from producing proteins and halts production of enzymes used for ATP hydrolysis (Patel, Biswas, & Maiti, 2016). This means that the cell is not able to produce some of its most important structures and the cell is not able to consume its energy stored in the form of ATP molecules. These metals provide an excellent solution for various applications requiring antimicrobial properties.
Antimicrobial nylon composites have numerous potential or current applications across numerous industries. Recent studies have evaluated the effectiveness of nanosilver coated polyamide-6,6 fabric as an antimicrobial treatment for textiles (Ribeiro, et al., 2019). This study found that nanosilver coated PA-6,6 fabrics were antimicrobial, with increased effectiveness after the surface of the fabric was treated with plasma to increase the adhesion of the nanosilver particles. Articles made from these treated fabrics could provide antimicrobial protection across the apparel industry to protect against odor-causing organisms, but the approach faces the challenge that, over time, this coating could wash off during cleaning and repeated use. The challenge of coating durability remains one of the more challenging aspects of antimicrobial coatings in textiles.
At NYCOA, we have the capabilities to mix these antimicrobial additives into our wide variety of specialty nylon grades to provide a longer-lasting antimicrobial treatment. Copper surfaces have also been used to reduce the spread of harmful bacteria in hospital settings by up to 58% (Salgado, et al., 2013). While this study looked at the use of metallic copper, nanocopper/polymer composites could provide similar results. These composite materials could provide reduced cost over pure metallic copper and could provide an easier manufacturing method to create a wider variety of antimicrobial surfaces, such as handles used for medical tools. NYCOA’s wide range of nylons could provide perfect carriers for antimicrobial additives used in applications ranging from soft-touch elastomeric handles to tough materials needed to replace stainless steel.
About NYCOA
NYCOA (the Nylon Corporation of America) commercially manufactures many grades of nylon, including NXTamid, a unique long-chain polyamide alternative to nylon 11 and nylon 12. All NYCOA products are made in the USA, manufactured in our ISO certified plant located in Manchester, NH. NYCOA is dedicated to plastics engineering, plastics innovation, and a consistent quality earned through operational excellence. NYCOA is dedicated to its customers, and produces specialty engineered polymers for industries and partners around the world, and has plastics compounding capabilities to produce a variety of reinforced and modified grades.
NYCOA manufactures specialty engineered polyamide (nylon) plastics for many industries and applications, including fasteners, hook and loop, extruded parts, injection molding, foamed components, monofilament, powders, and wire and cable jacketing.
References
Grass, G., Rensing, C., & Solioz, M. (2011). Metallic Copper as an Antimicrobial Surface. Applied and Environmental Microbiology, 1541-1547.
Patel, D. K., Biswas, A., & Maiti, P. (2016). Nanoparticle-induced phenomena in polyurethanes. Advances in Polyurethane Biomaterials, 171-194.
Ribeiro, A. I., Senturk, D., Silva, K. K., Modic, M., Cvelbar, U., Dinescu, G., & Mitu, B. (2019). Antimicrobial efficacy of low concentration PYP-silver nanoparticles deposited on DBD plasma-treated polyamide 6,6 fabric. Coatings, 581.
Salgado, C. D., Sepkowitz, K. A., John, J. F., Cantey, J. R., Attaway, H. H., Freeman, K. D., . . . Schmidt, M. G. (2013). Copper surfaces reduce the rate of healthcare-acquired infections in the intensive care unit. Infection Control and Hospital Epidemiology.