Metal nanoparticles-grafted functionalized graphene coated with nanostructured polyaniline 'hybrid' nanocomposites as high-performance biosensors

Metal nanoparticles-grafted functionalized graphene nanosheets with nanostructured polyaniline (PANi) 'hybrid' nanocomposites for ascorbic acid (AA) sensing is developed. The versatility of the nanocomposite performance was corroborated by altering size and density of electrodeposited gold (Au-NP) and silver (Ag-NP) nanoparticles on the graphene oxide; GO, thermally reduced GO; rGO(th) and nitrogenated functionalized graphene; NFG. These noble metal nanoparticles are selected due to higher electrical conductivity, facile synthesis, processability and antimicrobial nature. The multilayers (PANi vertical bar Ag-NP vertical bar GFN and PANi vertical bar Au-NP vertical bar GFN) on fluoride-doped tin oxide (FTO) coated glass, graphite foil (GF) and graphene rod (GR) electrodes were tested that show increased electrical conductivity and reduced charge transfer resistance. We demonstrated ultrasensitive detection of AA analyte over full range (from 1 x 10(-12) M to 10 x 10(-3) M) with linear sensitivity 10 mA mM(-1) cm(-2) and excellent limit of detection < 1 pM having high signal-to-noise ratio following PANi vertical bar Au-NP vertical bar NFG <= PANi vertical bar Ag-NP vertical bar NFG < Au-NP vertical bar NFG < Ag-NP vertical bar NFG. Specificity of the biosensor is assessed by interfering species commonly found in blood serum i.e. glucose (Glu) and uric acid (UA). We attribute these findings to synergistically coupled metal nanoparticles and functionalized graphene promoted localized orbital re-hybridization and heterogeneously integration with PANi. These multilayer 'hybrid' nanocomposite electrodes are also useful for platinum-free electrocatalysis, pseudocapacitors and biofuel cell development.