title: Eradicating group A streptococcus bacteria and biofilms using functionalised multi-wall carbon nanotubes.
abstract: OBJECTIVE
  The aim of this study was to demonstrate that multi-wall carbon nanotubes can be functionalised with antibodies to group A streptoccocus (GAS) for targeted photothermal ablation of planktonic and biofilm residing bacteria.
  
  
  METHODS
  Antibodies for GAS were covalently attached to carboxylated multi-wall carbon nanotubes and incubated with either planktonic or biofilm GAS. Bacterium was then exposed to 1.3 W/cm(2) of 800 nm light for 10-120 s, and then serially diluted onto agar plates from which the number of colony forming units was determined. Photothermal ablation of GAS on the surface of full thickness ex vivo porcine skin and histological sectioning were done to examine damage in adjacent tissue.
  
  
  RESULTS
  Approximately 14% of the GAS antibody-functionalised nanotubes attached to the bacterium, and this amount was found to be capable of inducing photothermal ablation of GAS upon exposure to 1.3 W/cm(2) of 800 nm light. Cell viability was not decreased upon exposure to nanotubes or infrared light alone. Compared to carboxylated multi-wall carbon nanotubes, antibody-labelled nanotubes enhanced killing in both planktonic and biofilm GAS in conjunction with infrared light. Analysis of GAS photothermally ablated in direct contact with ex vivo porcine skin shows that heat sufficient for killing GAS remains localised and does not cause collateral damage in tissue adjacent to the treated area.
  
  
  CONCLUSIONS
  The results of this study support the premise that carbon nanotubes may be effectively utilised as highly localised photothermal agents with the potential for translation into the clinical treatment of bacterial infections of soft tissue.
authors.affiliation: Department of Plastic and Reconstructive Surgery, Wake Forest University Health Sciences , Winston-Salem, North Carolina and.
authors.forename: Nicole
authors.initials: N
authors.lastname: Levi-Polyachenko
authors.forename: Christie
authors.initials: C
authors.lastname: Young
authors.forename: Christopher
authors.initials: C
authors.lastname: MacNeill
authors.forename: Amy
authors.initials: A
authors.lastname: Braden
authors.forename: Louis
authors.initials: L
authors.lastname: Argenta
authors.forename: Sean
authors.initials: S
authors.lastname: Reid
mesh_terms: D018441:Biofilms; D037742:Nanotubes, Carbon; D017550:Spectroscopy, Fourier Transform Infrared; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D037742:Nanotubes, Carbon
keywords: Carbon nanotubes; group A streptococcus; photothermal therapy