Optically Coupled Electronic Hybridizaton Chips

    A new electronically controlled DNA chip that consists of a glass substrate and indium tin oxide electrodes (ITO) has been developed. The glass substrate with ITO electrodes makes the chip transparent and enables detection of hybridization from below the surface of the chip via a CCD array which allows simplified detection optics and, possibly, improved sensitivity. ITO, however, is not inert and is susceptible to degradation or modification due to electrolysis at the electrodes. A chip design that incorporates donut-shaped platinum electrodes with ITO in the center hole was made to demonstrate functionality of the new transparent chips, hybridization and single base discrimination was demonstrated using a 20 nucleotide, perfectly matched duplex and single base mismatched duplexes with the mismatch located at different positions along the duplex. Single base discrimination was confirmed between the perfect match and all single base mismatched duplexes with the exception of that at the 3' and 5' ends. No noticeable degradation of the reactive ITO surface was seen during the tests indicating that the use of the transparent chips with ITO electrodes may be a feasible alternative to present silicon based chips with the advantage of simplified detection optics and possible improved sensitivity.

   Second generation ITO chip. The programmable electrodes consist of 100 donut shaped platinum electrodes with an ITO deposited layer in the center hole of each electrode. The four large auxiliary electrodes are partially shown in the four corners of the image.