O₂ plasma patterning of p-type MWCNT and its application to immunosensor

An electrochemical immunosensor based on patterned plasma-functionalized multiwalled carbon nanotubes (pf-MWCNTs) working electrode for Legionella pneumophila detection is described in this paper. Polyclonal antibody was immobilized using passive adsorption and covalent immobilization on the surface of the pf-MWCNTs. Various dilutions of Legionella 19-kDa peptidoglycan- associated lipoprotein (PAL) were added onto the electrode surface and incubated. The assay was then completed using polyclonal antibody conjugated to horseradish peroxidase (HRP) as the enzyme label. 3,3′,5,5′- Tetramethylbenzidine dihydrochloride (TMB)/substrate solution (H ₂O₂) was used as the mediator/substrate system. Electrochemical detection was conducted using cyclic voltammetric at 500 mV versus silver/silver chloride (Ag/AgCl) reference electrode. L. pneumophila detection of 0.16 ng ml^{- 1} and ∼ 0.0025 ng ml^{- 1} was achieved respectively for passive adsorption and covalent immobilization.