Could silver nanoparticles incorporated into microfiber cloths replace detergents or disinfectants?
Silver nanoparticles incorporated into textiles, such as microfiber cloths, is an interesting technology that proposes to be a sustainable solution for replacing detergents or disinfectants.
We looked a bit deeper into the potential of this technology but were unable to discern whether the silver nanoparticles prevent the spread of microorganisms picked up by the used cloth or whether it improves dirt removal.
Microfiber cloths with silver nanoparticles are new cleaning products appearing on the market that appeal to customers aiming to improve the sustainability profile of their business. These products tend to claim that water can replace the use of detergents or disinfectants when used. The products might even suggest antimicrobial activity against fungi, yeast, viruses or bacteria. However, the suggested antimicrobial performance relies on scientific publications made of silver nanotechnology, or on the reported antimicrobial claims of silver ions itself, as there is no accepted standardized method available to support antimicrobial claims for technology such as silver nanoparticle microfiber cloths. In some cases, a standardized test method (AATCC 100) was used, but the contact time for the test was between 18 and 24 hrs. In practice the silver nanoparticle microfiber cloth would have been washed at 60?C within this time, thereby killing most microorganisms present. There is also no clarity on how to register such a product under the Biocidal Product Regulation.
Incorporating silver nanoparticles into fabrics has become more common in the textile industry as consumers have a desire for clothing that is self-cleaning or free of bacteria (Deshmukh 2018). The antimicrobial performance of these silver nanoparticles incorporated into the textiles depends on the amount of silver ions or nanoparticles released from the material. This means silver nanoparticles will be released into the environment while washing the textile or it could be released into the sweat of your skin while using or wearing the textile. This has caused great concern about the impact silver nanotechnology might have on the environment and whether it is toxic to humans (Ferdous 2020), which requires further investigation by authorities.
Claims are made that silver nanoparticle microfiber cloths can be used with water alone to remove microorganisms from surfaces, but this is also true for microfiber cloths depending on the manufacturer. For instance, in a scientific study microfiber cloths used with water were shown to remove between 1 log (90%) to 3 log (99.9%) bacteria from the surface after cleaning (Robertson 2019). However, the used microfiber cloth transferred 3 log (99.9%) to 5 log (99.999%) picked up bacteria onto a new surface. Therefore, when using the microfiber cloth with water alone bacteria are removed but they can be transferred to other surfaces. When assessing the results reported for a commercial silver nanoparticle microfiber cloth claiming antimicrobial performance when used with water, a 3-log reduction (99.92% to 99.97%) of the test microorganism was observed. The log reduction was similar for both the microfiber cloth and the commercial silver nanoparticle microfiber cloth when used with water. The commercial cloth also performed superior to cotton cloth in removing microorganisms, but this is also true for microfiber cloths (Trajtman 2015). It is not transparent what the differences are between silver nanoparticle microfiber cloth and existing microfiber cloths, and more information is needed to discern the benefits of having silver nanoparticles present. It is also important to understand whether microorganisms are being transferred when using commercial silver nanoparticle microfiber cloth when cleaning with water as it might be similar to when using the microfiber cloth.
Due to a lack of standardized methods to understand microfiber cloths with silver nanoparticle antimicrobial properties with a contact time less than 18 hrs, it is impossible to claim that these products can replace detergents or disinfectants. Disinfectants typically can provide antimicrobial efficacy within minutes, and both detergents and disinfectants prevent the spread of microorganisms from the used cloth to other surfaces while cleaning (Robertson 2019). When a detergent was being used with a microfiber cloth, between 3 log (99.9%) and 5 log (99.999%) bacteria were removed, and less than 1 log was transferred to a new surface. Similarly, the disinfectant removed between 4 log (99.99%) and 6 log (99.9999%) bacteria and less than 1 log was transferred to a new surface. It could differ between which microorganisms or products are being tested, but this information supports that using detergents and disinfectants remains important for removing and preventing transferring microorganisms to new surfaces while cleaning, thereby reducing the spreading of a pathogen throughout a building.
In conclusion, even though silver nanotechnology is interesting, it remains a new terrain that requires regulation to understand its impact on the market to ensure consumer safety. The silver nanoparticle microfiber cloth does remove microorganisms from surfaces when used but proofs that the silver nanoparticles are needed to remove microorganisms by the microfiber cloth are lacking. An in-use comparison of the technology with traditional microfiber cloths is needed, when using water, detergents, and disinfectants. This is to understand whether picked-up microorganisms are transferred to other surfaces while cleaning. Antimicrobial claims supported by standardized test methods are also still lacking, since the currently used method has a contact time of 18 to 24 hours and within that time microorganisms would have been spread around to new surfaces during use.
References