DNA biosensor investigations in fish bile for use as a biomonitoring tool

Polycyclic aromatic hydrocarbons (PAH) are responsible for a number of adverse effects on aquatic biota due to their persistence and potential for accumulation. The recognition and quantification of biliary PAH metabolites from exposed fish represents a valuable tool in the evaluation of warning signals indicative of exposure. In this work, an electrochemical DNA biosensor is proposed as a screening device for the rapid detection of PAH metabolites in fish bile samples. Preliminary studies were performed using the 3-hydroxy-benzo(a)pyrene as a model compound. The effect of the 3-hydroxy-benzo(a)pyrene on the surface-confined DNA was found to be linearly related to the concentration of the PAH derivative in solution. Then, the DNA biosensor was used to investigate the presence of PAH metabolites in fish bile samples. The sensor was able to clearly distinguish PAH-exposed fish bile samples from unexposed control samples. A total analysis time of 7 min was established (including electrode surface pre-treatment, dsDNA immobilization and interaction steps) and only 10muL of diluted sample solution were needed. DNA biosensors are cost effective and sensitive; moreover, the coupling of a portable and battery-operating potentiostat with disposable carbon strips meets the requirements for in situ measurements.