A novel amperometric inhibition biosensor based on HRP and gold sononanoparticles immobilised onto Sonogel-Carbon electrode for the determination of sulphides

ABSTRACT

A novel inhibition biosensor used for the detection of sulphides (Na₂S) has been developed. The biosensor is based on the immobilisation of horseradish peroxidase (HRP) on the Sonogel-Carbon (SNGC) electrode using glutaraldehyde, Poly(4-vinylpyridine) and gold sononanoparticles (AuSNPs). The Poly(4-vinylpyridine) was used due to its high affinity for sulphide anions, while the presence of gold sononanoparticles enhances the electron transfer reaction and improves the analytical performance of the biosensor. The amperometric measurements were performed at an applied potential of −0.15 V vs. Ag/AgCl in 50 mM sodium acetate buffer solution pH = 6.0. The apparent kinetic parameters (K_mapp, V_max) of immobilised HRP were calculated in the absence of inhibitor (sulphide) using caffeic acid as substrate. Under the optimal experimental conditions, the determination of sulphide can be achieved in a dynamic range of 0.4–2.8 µM with a low limit of detection of 0.15 µM. The electrochemical impedance spectroscopy (EIS) was also used to characterise the interactions of substrate and inhibitor with the enzyme-modified electrode. The developed biosensor exhibited high sensitivity, selectivity and stability, and can be successfully applied to the detection of sulphide in water.

KEYWORDS:

• Enzyme biosensor
• gold sononanoparticles
• horseradish peroxidase
• poly(4-vinylpyridine)
• Sonogel-Carbon electrode
• sulphide

Acknowledgements

The authors are grateful to the Spanish Agency for International Cooperation and Development (AECID - Foreign Affairs Ministry of Spain) for financially supporting this work in the frame work of the project AP/038929/11. Financial support from the Junta de Andalucía (Spain), NATO Science for Peace project SFP.984173 and the European Commission 7th Framework Programme Marie Curie Actions EP7- People-2011-IRSES N°PRISES-GA-2011-294901 PEPTIDE NANOSENSORS are also acknowledged. We would like to acknowledge as well the funding through the European Communities Seventh Framework Programme entitled Sea-on-a-Chip (FP7-OCEAN-2013) (No.614168) and funding from the European Union’s Horizon 2020 research and innovation programme entitled HEARTEN under grant agreement No 643694”. The author Aisha Attar gratefully acknowledges besides Dr Ilias Marmouzi for all support provided.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

The authors are grateful to the Spanish Agency for International Cooperation and Development (AECID – Foreign Affairs Ministry of Spain) for financially supporting this work in the frame work of the project AP/038929/11. Financial support from the Junta de Andalucía (Spain), NATO Science for Peace project SFP.984173 and the European Commission Seventh Framework Programme Marie Curie Actions EP7- People-2011-IRSES N°PRISES-GA-2011-294901 PEPTIDE NANOSENSORS are also acknowledged. We would like to acknowledge as well the funding through the European Communities Seventh Framework Programme entitled Sea-on-a-Chip (FP7-OCEAN-2013) [grant number 614168] and funding from the European Union’s Horizon 2020 research and innovation programme entitled HEARTEN [grant agreement number 643694].