Tetracarboxylic acid cobalt phthalocyanine SAM on gold: Potential applications as amperometric sensor for H[subscript 2]O[subscript 2] and fabrication of glucose biosensor

Mashazi, P.N. and Ozoemena, K.I. and Nyokong, T. (2006) Tetracarboxylic acid cobalt phthalocyanine SAM on gold: Potential applications as amperometric sensor for H[subscript 2]O[subscript 2] and fabrication of glucose biosensor. Electrochimica Acta, 52 (1). pp. 177-186. ISSN 0013-4686

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Official URL: http://dx.doi.org/10.1016/j.electacta.2006.04.056

Abstract

This report describes the applications of cobalt tetracarboxylic acid phthalocyanine (CoTCAPc) self-assembled monolayer (SAM) immobilized onto a preformed 2-mercaptoethanol (Au-ME) SAM on gold surface (Au-ME-CoTCAPc SAM) as a potential amperometric sensor for the detection of hydrogen peroxide (H[subscript 2]O[subscript 2]) at neutral pH conditions. The Au-ME-CoTCAPc SAM sensor showed a very fast amperometric response time of approximately 1 s, good linearity at the studied concentration range of up to 5 μM with a coefficient R² = 0.993 and a detection limit of 0.4 μM oxidatively. Also reductively, the sensor exhibited a very fast amperometric response time (~1 s), linearity up to 5 μM with a coefficient R² = 0.986 and a detection limit of 0.2 μM. The cobalt tetracarboxylic acid phthalocyanine self-assembled monolayer was then evaluated as a mediator for glucose oxidase (GOx)-based biosensor. The GOx (enzyme) was immobilized covalently onto Au-ME-CoTCAPc SAM using coupling agents: N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS), and the results demonstrated a good catalytic behavior. Kinetic parameters associated with the enzymatic and mediator reactions were estimated using electrochemical versions of Lineweaver–Burk and Hanes equation, and the stability of the sensor was tested. The biosensor (Au-ME-CoTCAPc-GOx SAM) electrode showed good sensitivity (7.5 nA/mM) with a good detection limit of 8.4 μM at 3σ, smaller Michaelis–Menten constant (4.8 mM from Hanes plot) and very fast response time of approximately 5 s.

Item Type:Article
Additional Information:Corresponding author, Kenneth I. Ozoemena. Tel.: +27 12 4202515; fax: +27 12 3625297. E-mail: kenneth.ozoemena@up.ac.za
Uncontrolled Keywords:Cobalt phthalocyanine; Glucose oxidase; Self-assembled monolayer; Hydrogen peroxide; Glucose; Impedance spectroscopy
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Chemistry
ID Code:419
Deposited By: Mrs Eileen Shepherd
Deposited On:31 Oct 2006
Last Modified:06 Jan 2012 16:18
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