Antibacterial and Antibiofouling Activities of Antimicrobial
Peptide-Functionalized Graphene–Silver Nanocomposites for the
Inhibition and Disruption of Staphylococcus aureus Biofilms
posted on 2021-11-17, 14:37authored byThanusu Parandhaman, Priyadarshani Choudhary, Baskaran Ramalingam, Michael Schmidt, Sridevi Janardhanam, Sujoy K. Das
Owing
to the emergence of antibiotic-resistant strains, bacterial
infection and biofilm formation are growing concerns in healthcare
management. Herein, we report an eco-benign strategy for the synthesis
and functionalization of graphene–silver (rGOAg) nanocomposites
with an antimicrobial peptide (AMP) for the treatment of Staphylococcus aureus infection. The synthesis of
rGOAg nanocomposites was carried out by simple microwave reduction,
and the as-synthesized rGOAg was covalently functionalized with an
AMP. As a natural AMP, poly-l-lysine (PLL) functionalization
of rGOAg enhanced the antibacterial efficacy and target specificity
against the S. aureus biofilm. The
robust bactericidal efficiency and biofilm disruption by AMP-functionalized
rGOAg (designated as GAAP) occurred through the “contact–kill–release”
mode of action, where the electrostatic interaction with bacterial
cells together with intracellular ROS generation induced physical
disruption to the cell membrane. The internalization of GAAP into
the cytoplasm through the damaged cell membrane caused an outburst
of intracellular proteins and DNA. Crystal violet staining along with
fluorescence and confocal microscopic images showed an effective inhibition
and disruption of the S. aureus biofilm
upon treatment with GAAP. PLL functionalization also prevented the
dissolution of Ag+ ions and thereby minimized the in vitro
toxicity of GAAP to the 3 T6 fibroblast and human red blood cells.
The ex vivo rat skin disinfection model further demonstrated the potency
of GAAP in eliminating the biofilm formation and disruption of the S. aureus biofilm. The obtained results demonstrated
a general approach for designing a functional nanocomposite material
to disrupt the mature biofilm and provided a promising strategy for
treating bacterial infection.