Shape-dependent electron transfer kinetics and catalytic activity of NiO nanoparticles immobilized onto DNA modified electrode: Fabrication of highly sensitive enzymeless glucose sensor

• GC electrode modified with DNA was used as a template for the electrodeposition of NiONPs.
• NiONPs deposited onto DNA/GCE shows triangular shape, while the electrodeposition of NiONPs on the bare GCE leads to the formation of spherical NPs.
• Triangular NiONPs shows higher charge transfer kinetics compared to spherical form.
• Electrocatalytic activity of triangular NiONPs toward detection of glucose was improved compared to the spherical form.
• The sensor was used for analysis of glucose in real samples with a detection limit of 17 nM.

Herein we describe improved electron transfer properties and catalytic activity of nickel oxide nanoparticles (NiONPs) via the electrochemical deposition on DNA modified glassy carbon electrode (DNA/GCE) surface. NiONPs deposited on the bare and DNA-coated GCE showed different morphologies, electrochemical kinetics and catalytic activities. The atomic force microscopy (AFM) images revealed the formation of triangular NPs on the DNA/GCE that followed the shape produced by the DNA template, while the electrodeposition of NiONPs on the bare GCE surface led to the formation of spherical nanoparticles. Electrochemical impedance spectroscopy (EIS) measurements revealed lower charge-transfer resistance (Rct) of triangular NiONPs compared to spherical NPs. Furthermore, the electrocatalytic activity of triangular NiONPs compared to spherical NPs toward glucose oxidation in alkaline media was significantly improved. The amperometric oxidation of glucose at NiONP–DNA/GCE, yielded a very high sensitivity of 17.32 mA mM−1 cm−2 and an unprecedented detection limit of 17 nM. The enhanced electron transfer properties and electrocatalytic activity of NiONP–DNA/GCE can be attributed to the higher fraction of sharp corners and edges present in the triangular NiONPs compared to the spherical NPs. The developed sensor was successfully applied to the determination of glucose in serum samples.

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