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Metal-Enzyme Nanoaggregates Eradicate Both Gram-Positive and Gram-Negative Bacteria and Their Biofilms

Year: 2018

Journal: ACS Appl. Mater. Interfaces, Volume 10, NOV 28, page 40434–40442

Authors: Ferreres, Guillem; Bassegoda, Arnau; Hoyo, Javier; Torrent-Burgues, Juan; Tzanov, Tzanko

Keywords: silver; alpha-amylase; lactase; metal-enzyme nanoaggregates; antibacterial and antibiofilm effect

To palliate the appearance of antimicrobial resistance (AMR), the use of bactericidal agents acting differently than conventional antibiotics and the elimination of bacterial biofilm, are the two most promising strategies. Here, we integrated these two complementary strategies into new antimicrobial metal-enzyme nanoaggregates (NAs) of alpha-amylase and silver (alpha AgNAs) that are able to eliminate bacteria and their biofilm. The nanoparticle (NP) synthesis approach applied protein desolvation and laccase-mediated NP stabilization to innovatively produce catalytically active alpha-amylase nanoparticles (alpha NPs) for the elimination of the bacterial biofilm. At the same time, alpha NPs efficiently reduced silver for the incorporation of bactericidal Ag-0 and formation of the alpha AgNAs. The bactericidal and antibiofilm efficacies of aAgNAs were demonstrated by 5.4 and 6.1 log reduction of Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, respectively, and more than 80% removal of their biofilms, coupled with high biocompatibility. The biofilm-alpha AgNA interaction was assessed by quartz crystal microbalance and atomic force microscopy revealing how the degradation of a settled biofilm by aAgNAs caused an increase of the biofilm water content, thus weakening the biofilm surface attachment and facilitating its removal. With the present work, we not only provide a new efficient antimicrobial material to face the AMR threat, but we also envisage that the newly established method for the synthesis of metal-enzyme NAs is potentially transferable to other biocatalysts to expand the enzyme NP toolbox.