With surfaces, many types of microorganisms can persist for extended periods of time (some bacteria can survive for longer than thirty days on standard surfaces). The survival mechanism includes coronaviruses (although the extent that the viral particles retain the ability to be infectious is for a shorter period of time compared with the general recovery of viral RNA).
In many settings, especially in healthcare, touch-surfaces represent risk spots for pathogen transmission. In many sectors, especially healthcare, some types of key equipment are manufactured with antimicrobial touch components. This is with the aim ensuring the surfaces are self-disinfecting.
Copper
A recent trend in the hospital setting has been to revisit the inherent antimicrobial properties of copper. Copper, and copper alloys (such as brass, cupronickel, copper-nickel-zinc, and bronze), are inherently antimicrobial. Experimental data shows copper possesses a rapid, broad-spectrum efficacy against bacteria and viruses, and it can kill viral pathogens such as influenza A and norovirus.
Silver
A second metal of interest is silver (albeit one more expensive than copper). Silver is a powerful antimicrobial agent, showing effectivity against a variety of microorganisms. Once the element has entered the bacterial cell, it accumulates as silver nanoparticles with large surface area causing cell death. The process is also aided by the bacterial cell becomes a reservoir for silver, passing on silver ions to other cells.
The silver-killing effect of bacterial cells was explored in a recent paper:
Mohamed, D. S., El-Baky, R.M.A, Sandle, T., Mandour, S. A. and Ahmed, E. F. (2020) Antimicrobial Activity of Silver-Treated Bacteria against other Multi-Drug Resistant Pathogens in Their Environment, Antibiotics, 9 (4),181
Silver is also being incorporated into wound dressings, where dressings contain silver and alginates (typically as either silver alginate or silver carboxymethylcellulose). Silver is a broad-spectrum agent and when bound within a dressing, it can help to prevent wound infection.
Surface roughness
The texture of a surface can also affect its antimicrobial properties. For example, Purdue University engineers created a laser treatment method that could potentially turn any metal surface into a rapid bacteria killer — just by giving the metal’s surface a different texture.
The practice of laser-texturing has a dual effect: The technique makes direct contact with an antimicrobial surface more likely and it makes a surface more hydrophilic, which can make microbial attachment more likely. This technology is being considered in relation to surgical implants.
Coronavirus
Given the established research around antimicrobial surfaces, can such surfaces assist with COVID-19 prevention measures? Lux Research has issued a new report that considers materials innovations dealing with antimicrobial coatings and the extent that these can be used in tackling the SARS-CoV-2 coronavirus.
The report is titled “Antimicrobial Coatings at the Front Line of COVID-19“, and it considers the important challenges and opportunities for coatings, additives, and materials innovation and how such innovations will impact across several major sectors.
While silver and copper continue to rate high as the best materials to include where the killing of bacteria and viruses is required, important challenges include outlining the effectiveness when the selected antimicrobial is dispersed in coating matrices.
As well as the use of specific additives, research is focusing on photocatalytic, enzyme-based, and bio-based coatings. Such coatings are still to be assessed through appropriate trials. Also to be are assessed are issues of durability, and what happens in terms of properties when a surface becomes worn or damaged (as will arise in the clinical setting).
There is considerable interest with light-activated, photocatalytic coatings. Such coatings deploy materials like nano-titanium dioxide that absorb ultra-violet light and then produce reactive radicals that break down organic compounds on surfaces. Until now, photocatalytic coatings have been used to eliminate pollutants. Attention has recently turned to anti-viral applications.
With bio-based antimicrobial technologies, this has been explored in relation to food packaging. This technology could expand to other surfaces beyond food-wrapping plastics. Antimicrobial enzymes present a different option, in terms of producing reactive oxygen species that can kill organisms when activated by light.
Cleaning and disinfection
While antimicrobial surfaces can contribute to the fight against coronavirus they are not a substitute for regular and effective cleaning and disinfection. Surfaces should continue to be sanitized on a regular basis.
Essential Science
This article forms part of Digital Journal’s long-running Essential Science series. Each week we present a new science finding, covering a diverse range of subjects.
Last week, we considered a new study, from the University of Virginia Health System that suggested that the use of an online calculator can predict an individual’s stroke risk. This, and other studies relating to stroke risk were considered in the article.
The week before topic was venom from honeybees and the potential role played in inactivating aggressive breast cancer cells, as based on a series of laboratory studies. This research paves the way for more in-depth assessment and a potential medical treatment.
