Bioelectrocatalytic determination of nitrite ions based on polyaniline grafted nanodiamond

Polyaniline chains were grafted onto nanodiamond (PANI-g-ND) through electrochemical polymerization of aniline in the presence of amine functionalized ND. A robust and effective composite film comprising PANI-g-ND/gold particles was subsequently prepared. Cytochrome c was successfully immobilized onto PANI-g-ND/Au film. Field emission scanning electron microscope (FESEM) image of PANI-g-ND/Au reveals the presence of fibrous PANI embedded into ND galleries with uniformly distributed Au clusters (∼1 μm). Direct electrochemistry and electrocatalysis of cyt c were investigated. PANI-g-ND/Au film showed an obvious direct electron transfer between cyt c and the underlying electrode. Cyclic voltammograms revealed that PANI-g-ND/Au/cyt c exhibited an excellent electrocatalysis towards the detection of nitrite ions. Differential pulse voltammetry of PANI-g-ND/Au/cyt c revealed a wide linear concentration range (0.5 μM–3 mM) for current responses, sensitivity (88.2 μA/mM) and low detection limit (0.16 μM) towards the electrochemical detection of nitrite ions.