Enhanced electrochemiluminescence from luminol at multi-walled carbon nanotubes decorated with palladium nanoparticles: A novel route for the fabrication of an oxygen sensor and a glucose biosensor

Incorporation of palladium nanoparticles on the surface of multi-walled carbon nanotubes and modification of glassy carbon electrode with the prepared nano-hybrid material led to the fabrication of a novel electrode. The modified electrode showed attractive electrocatalytic activity and sensitizing effect on luminol–O2 and luminol–H2O2 electrochemiluminescence (ECL) reactions at neutral media. The sensitized luminol–O2 and luminol–H2O2 reactions were successfully applied for the ECL determination of dissolved O2 and glucose, respectively. Under the optimal conditions for luminol–O2 system, the ECL signal intensity of luminol was linear with the concentration of dissolved oxygen in the range between 0.08 and 0.94 mM (r = 0.9996) and for luminol–H2O2 system, the ECL signal intensity of luminol was linear with the concentration of glucose in the range between 0.1 and 1000 μM (r = 0.9998). The limits of detection (S/N = 3) for dissolved oxygen and glucose were 0.02 mM and 54 nM, respectively. The relative standard deviations (RSD) for repetitive measurements of 0.50 mM oxygen (n = 10) and 10 μM glucose (n = 30) were 3.5% and 0.3%, respectively. Also, under the optimal conditions for luminol–H2O2 system, the ECL signal intensity of luminol was linear with the concentration of H2O2 in the range between 1 nM and 0.45 mM (r = 0.9997). The limit of detection (S/N = 3) for H2O2 detection was 0.5 nM and the relative standard deviation for repetitive measurements of 10 μM H2O2 (n = 10) was 0.8%.

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► Glassy carbon electrode was modified with Pd nanoparticles decorated MWCNTs.
► Modified GCE showed sensitizing effect on luminol-O2 and luminol-H2O2 ECL reactions.
► The sensitized ECL reactions were conducted at neutral media.
► Dissolved O2, luminol, H2O2 and glucose were determined using the proposed modified GCE.