Antibacterial Surfaces Produced by Liquid Flame Spray Deposition of Silver Nanoparticles

G5 Doctoral dissertation (article)

Internal Authors/Editors

Publication Details

List of Authors: Kofi Jocelyn Brobbey
Publisher: Åbo Akademi
Place: Turku
Publication year: 2019
ISBN: 978-952-12-3812-3
eISBN: 978-952-12-3813-0


associated infections (HAIs) are one of the major problems of modern
healthcare. Pathogenic bacteria responsible for these HAIs are mostly
transmitted via surfaces. Emphasis on preventive measures can cumulatively
reduce associated costs and mortality related to HAIs. Antibacterial surfaces
within healthcare settings have been considered as one of the approaches to
reduce HAIs. Therefore, further development and wide use of antibacterial
surfaces in healthcare settings could be a step that helps to significantly
reduce the problem. Nanoparticles (NPs), plant extracts and other inorganic
substances have been used for the production of antibacterial surfaces. Particularly,
silver nanoparticles (AgNPs) have been shown to have broad-spectrum
antibacterial properties, which has resulted in its wide use for fabricating
antibacterial products. NP production methods have also evolved continuously,
but a production method that allows for continuous synthesis of NPs and their
deposition on surfaces had been elusive until the development of Liquid Flame
Spray (LFS). LFS enables high speed NP deposition without effluents, and it is
suitable for producing large-area antibacterial surfaces. In this project, LFS
was used to deposit AgNPs onto paper, glass and fabrics to produce
antibacterial surfaces. After NP deposition, scanning electron microscopy and
atomic force microscopy (AFM) were used to visualize the samples. Surface
chemical characterization was done using x-ray photoelectron spectroscopy, and
silver leaching tests were analyzed using inductive coupled plasma-mass
spectroscopy. NP adhesion to substrates was improved using thin plasma polymer
coating layer, as well as Al2O3 produced by atomic layer
deposition. Antibacterial properties were examined using a newly developed
‘Touch Test’ method, which simulates the transfer of bacteria from one surface
to another by touch. Imaging results showed that nanoparticles are produced,
and multiple flame passes result in the deposition of more AgNPs on sample
surfaces. AFM scratch testing in contact mode confirmed results of improved NP
adhesion by plasma coating. Antibacterial action against E. coli, S. aureus, and other bacteria was demonstrated, and in the
case of E. coli, also for samples
that had a thin layer of plasma coating on top of AgNPs. The exact mechanism of
the antibacterial effect from below the plasma coating requires further
investigation, since usually a direct contact to AgNPs is assumed to be a
prerequisite. However, the results of this study suggest that a thin
immobilizing layer can be used to improve the adhesion of AgNPs to substrates
and to limit their exposure to environment, while still maintaining the desired
antibacterial properties.

Keywords: silver, nanoparticles,
liquid flame spray (LFS), antibacterial, paper, glass, fabrics, immobilization,
plasma coating, AFM scratch testing, silver leaching


AFM, antibacterial property, Glass, Immobilization, Liquid Flame Spray (LFS), Paper coating, plasma coating, Silver leaching, Silver nanoparticles

Last updated on 2019-16-12 at 03:37