Introduction:
High-touch surfaces are potential reservoirs of pathogenic bacteria and viruses. SARS-CoV-2 pandemic is a well-known example. These contaminated surfaces serve to be a major source of nosocomial infection. Regular cleaning and disinfection to destroy the pathogens is costly and cannot feasibly be conducted with sufficient frequency to be fully effective. Here, self-disinfecting surfaces could easily prevent the disease transmission to a great extent. Let’s see what researchers have developed to serve this purpose.
The latest research conducted by Davood Nakhaie and team at The University of British Columbia sheds light on the development of self-sanitizing surfaces by utilizing the antimicrobial properties of copper. In their research article titled “An Engineered Nanocomposite Copper Coating with Enhanced Antibacterial Efficacy” shows how a nanocomposite copper (Cu) coating is created that decreases the microbial bioburden of Gram-positive Staphylococcus aureus by 94% compared to unmodified Cu.
Research:
Copper is know to possess the bactericidal and viricidal properties. So, it’s coating can minimize the spread of microorganisms and viruses on high-touch surfaces. The antimicrobial behavior of Cu-based surfaces depends on their ability to release free Cu ions. Thus, ensuring the rapid and continuous release of Cu ions is crucial in rapid killing of pathogens and maintenance of Cu’s self-sanitizing properties for long-term. Cu is less effective against Gram-positive bacteria than Gram-negative bacteria because of the variation in peptidoglycan wall thickness, which is thicker in Gram-positive bacteria like S. aureus, that is responsible for skin and wound infections and is increasingly resistant to antibiotics.
To overcome this, a multi-functional Cu coating is engineered to enhance its antibacterial efficacy towards Gram-positive bacteria. The coating technology combines Cu nanoparticles with a cationic polymer, linear polyethyleneimine (LPEI), having antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria as well as viruses. This results in 52% increase in antibacterial efficacy against S. aureus. The incorporation of nanotopography has also been found to kill bacteria by rupturing their cell wall. Lastly, leveraging the difference in standard reduction potential between Cu (0.34 V vs SHE) and Zn (−0.76 V vs SHE) drives the rapid and selective leaching of antimicrobial Zn ions, which improves antibacterial efficacy. The addition of CuCl2 and ZnCl2 salts to the coatings led to the formation of surface roughness across multiple length scales, thus increasing the coating hydrophobicity and hindering the bacterial adhesion to surfaces. This remarkably increases the efficacy to 86.8% and 94% at 60 min, for CuCl2 and ZnCl2 respectively.
Conclusion:
By observing the inherently bactericidal nanostructured surfaces found in nature, researchers have successfully developed an improved Cu coating, engineered to contain nanoscale surface features which increases its antibacterial activity against a wider range of organisms. The incorporation of nanoscale surface features alone resulted in 52% increase in antibacterial efficacy against S. Aureus which is further increased to 94% by fabricating the coating in the presence of ZnCl2. The development of such new technologies mitigating the spread of nosocomial infections leading to considerable patient morbidity and mortality is indeed critical.
Reference:
Davood Nakhaie et al, An Engineered Nanocomposite Copper Coating with Enhanced Antibacterial Efficacy, Advanced Materials Interfaces (2022).
By Aditi Singh
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