Selective Antimicrobial and Antibiofilm Disrupting Properties of Functionalized Diamond Nanoparticles Against Escherichia coli and Staphylococcus aureus

Diamond nanoparticles (NDs) have demonstrated great promise as useful materials in a variety of biomedical settings. In this paper, the antimicrobial and antibiofi lm activities of variously functionalized NDs against two common bacterial targets Gram-negative bacterium Escherichia coli and Gram-positive bacterium Staphylococcus aureus are compared. Hydroxylated (ND-OH), aminated (ND-NH 2 ), carboxylated (ND-COOH), mannose (ND-Mannose), tri-thiomannoside (ND-Man 3 ), or tri-thiolactoside (ND-Lac 3) - modifi ed NDs are fabricated and evaluated in the present work. Of these, the mannose-modified NDs are found to interfere most strongly with the survival of S. aureus, but not to influence the growth of E. coli . In contrast, particles featuring lactosyl units have the opposite effect on S. aureus growth. Sugar-functionalized NPs reported to display antibacterial effects are rare. Only ND-COOH particles are seen to have any effect on the growth profile of E. coli, but the effects are moderate. On the other hand, both ND-NH 2 and ND-COOH are found to inhibit E. coli -induced biofilm formation at levels comparable to the known E. coli biofilm disruptor, ampicillin (albeit at concentrations of 100 μg mL -1). However, none of the modified particles examined here reveal any significant activity as disruptors of S. aureus -induced biofilm formation even at the highest concentrations studied.