Development of microplate-based photoelectrochemical DNA biosensor array for high throughput detection of DNA damage

Many chemicals have been found to induce DNA damages which may lead to gene mutation and tumor generation. In this report, a microplate-based photoelectrochemical DNA sensor array was developed for the rapid and high throughput screening of DNA damaging chemicals. A 96-well plate with built-in electrodes was fabricated on a plastic substrate by the standard electronics industry processes. The working electrode in each well was deposited with SnO2 nanoparticles, and the resulting film was sintered at low temperatures tolerable for the plastic substrate. The film was characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. On the plates sintered at 150 °C, a significant amount of photocurrent was obtained in a Ru(bpy)32+ (bpy = 2,2′-bipyridine) solution. To construct a DNA sensor, poly-(diallydimethyl ammonium chloride) and double-stranded DNA were sequentially assembled on the SnO2 electrode by electrostatic interaction, and a DNA intercalator, Ru(bpy)2(dppz)2+ (dppz = dipyrido[3,2-a:2′,3′-c]phenazine) was used as the photoelectrochemical signal indicator. After the DNA film was exposed to tetrafluoro-1,4-benzoquinone (TFBQ) or TFBQ/H2O2, the photocurrent dropped by 38% and 73% respectively. The photocurrent reduction can be attributed to less binding of Ru(bpy)2(dppz)2+ to the electrode after DNA damage. Photocurrent measurement of the entire 96-well plate was completed within 22 min automatically.