Zinc Metalloporphyrin-Modified Electrode for Electrochemical Sensing of Noradrenaline

Abstract

Noradrenaline is an important catecholamine neurotransmitter involved in cardiovascular, neuroendocrine, and neuronal functions, and altered levels have been associated with pathological conditions. In this study, a zinc metalloporphyrin, mono-maleimide-tetraphenylporphyrinatozinc(II), was combined with multi-walled carbon nanotubes to develop a modified glassy carbon electrode for the electrochemical detection of noradrenaline. The contribution of the zinc metalloporphyrin to the sensing interface was investigated by comparing zinc-containing and metal-free porphyrin systems. Incorporation of zinc resulted in a two-fold increase in anodic peak current and a reduction in charge-transfer resistance from 0.377 to 0.161 kΩ, indicating improved interfacial electron-transfer kinetics. Under optimised differential pulse voltammetry conditions, the modified electrode exhibited a linear response to noradrenaline from 1.0 to 84.2 µmol L –1 , with a detection limit of 0.26 µmol L –1 . The electrode also provided consistent recoveries of noradrenaline in spiked synthetic urine and bovine serum samples. These results demonstrate the functional contribution of the zinc metalloporphyrin to the carbon nanotube-based sensing interface and support its potential for electrochemical noradrenaline detection in complex samples.

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