GRAPHITE ELECTROCHEMICAL SENSORS FOR THE EVALUATION OF PAHs-DNA ADDUCTS

摘要

The aim of this experimentation was the evaluation of benzo(a)pyrene-DNA adducts (BaP-DNA adducts) formation using graphite screen printed electrodes (SPE) and chronopotentiometry. Graphite electrochemical sensors appeared a useful tool for the realization of a rapid method of analysis for the detection of BaP-DNA adducts. To test the performance of these devices the electrochemical response produced by genomic DNA sequences adsorbed on the electrochemical transducer was characterized. A concentration dependent oxidation peak was observed at +1.050 mV vs Ag/AgCl reference electrode, this peak is due to the guanine oxidation. Moreover the response of the immobilized DNA to BaP, and other polycyclic aromatic hydrocarbons (PAHs), was characterized. Depending on the hydrophobicity of the target molecule either a decrease (>3 aromatic rings) or an increase (<3 aromatic rings) of the guanine oxidation peak was observed. A combination of UV light and oxidising conditions (0.4 μM H_2O_2) were used to obtain oxygenated species such as diol epoxide. Under these experimental conditions the formation of oxidised BaP ((ox)BaP) derivatives was followed by UV spectra monitoring the appearance of an absorbance maximum at λ=264 nm. The formation of (ox)BaP-DNA adducts was evaluated by chronopotentiometry using screen printed electrodes.