Sol-gel-derived array DNA biosensor for the detection of polycyclic aromatic hydrocarbons in water and biological samples

The sol-gel-derived array DNA biosensors coupled with a fluorescence detection system and a robotic pin-printing platform were fabricated to detect polycyclic aromatic hydrocarbons (PAHs) in water and serum samples. Parameters including sol percentage, doped-amount of glycerol, dye probes, the surface coating, and DNA concentration were optimized. In addition, two fluorescent dyes, fluorescein isothiocyanate (FITC) and ethidium bromide (EDB) were selected and compared. Results showed that EDB was more sensitive to compete intercalators (PAHs) than FITC, and was selected as fluorescent dye for array-based DNA biosensors. The optimized procedure with dsDNA concentration of 23.5 μg/ml allowed the fabrication of the DNA biosensor up to 50 spots within 10 min via the developed pin-printing system. For PAH detection, the developed array DNA biosensor effectively detected naphthalene and phenanthrene in the concentration range of 0-10 mg/l in aqueous solution, but was not sensitive to fluoranthene and benzo[a]pyrene. In the serum samples, the apparent water solubility of high-molecular-weight PAHs was greatly enhanced by the dissolved organic compounds in serum, and an obvious DNA toxicity was exhibited in the presence of three- to five-ring PAHs. Benzo[a]pyrene showed high toxic effect at low concentration in serum samples, clearly showing that the sol-gel-derived array DNA biosensor with EDB as sensing probe can effectively detect PAHs in water and biological samples.