Abstract
A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme superoxide dismutase has been developed. The oxidation signal of epinephrine substrate was affected by the presence of Al(III) ions leading to a decrease in its amperometric current. The immobilization of the enzyme was performed with glutaraldehyde on screen-printed carbon electrodes modifiedwith tetrathiofulvalene (TTF) and different types ofnanoparticles. Nanoparticles of gold, platinum, rhodium and palladium were deposited on screen printed carbon electrodes by means of two electrochemical procedures. Nanoparticles were characterized trough scanning electronic microscopy, X-rays fluorescence, and atomic force microscopy. Palladium nanoparticles showed lower atomic force microscopy parameters and higher slope of aluminum calibration curves and were selected to perform sensor validation. The developed biosensor has a detection limit of 2.0 ± 0.2 μM for Al(III), with a reproducibility of 7.9% (n = 5). Recovery of standard reference material spiked to buffer solution was 103.8% with a relative standard deviation of 4.8% (n = 5). Recovery of tap water spiked with the standard reference material was 100.5 with a relative standard deviation of 3.4% (n = 3). The study of interfering ions has also been carried out.
Highlights
Aluminum toxicity has been shown in vivo and in vitro, but complexity of its interactions with human organism makes it very difficult to assign the responsibility in Alzheimer’s disease
superoxide dismutase (SOD) activity [58], this study indicates that Al(III) SOD inhibition can be performed at lower potential compared to other aluminum enzymatic determinations
EPI originates an amperometric signal at NPs/SPCTTFE with SOD enzyme immobilized ions produces SOD enzyme inhibition which causes a decrease in the EPI amperometric signal
Summary
Aluminum toxicity has been shown in vivo and in vitro, but complexity of its interactions with human organism makes it very difficult to assign the responsibility in Alzheimer’s disease. Biosensors have employed superoxide dismutase (SOD), an enzyme that scavenges superoxide to measure superoxide anion with the reactions [5]: Cu2+ − SOD + O2 − → Cu1+ − SOD + O2
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