Description
Research to understand the electrical properties of DNA as an electrical component continues with the objective of determining the use of DNA as the next generation nanoelectronics component. This study experimentally investigates the possibility of creating electronic platforms for DNA using carbon electrodes generated from patterned negative tone photoresist. The use of negative tone photoresist allows for the development of three dimensional platforms consisting of electrodes and traces that can be designed and patterned using conventional lithography techniques. In this study, electrodes with bump pads were designed and manufactured using negative tone photoresist. In order to alter the structure of the negative tone photoresist into a form of conductive carbon, the photoresist structure underwent a pyrolysis heating process. In the pyrolysis process, a reduction in oxygen was expected. This decrease in oxygen was confirmed by Electron Dispersion X-ray Spectroscopy (EDX). By nature, carbon tends to be inert except at edges and defect locations. In order to attach anything to carbon, the area of attachment needed to be functionalized. Functionalization of carboxyl group on the surface of the electrode was done via oxygen plasma treatment. Confirmation of carboxyl groups was done with EDX and FTIR. With carboxyl groups on the surface of the pyrolyzed carbon, carboxyl-amine cross linkers could be used to attach aminated oligonucleotides. This was done utilizing a reaction between 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (Sulfo-NHS) to generate a peptide bond between the carboxylated electrode and the aminated oligonucleotide. After the carboxyl-amine crosslinking reaction was completed, the sticky ends of the _-DNA were hybridized with complementary oligonucleotides. Successful oligonucleotide and DNA attachment were confirmed using fluorescence. While many approaches have been made to attach DNA onto carbon, this method differs in that (i) negative tone photoresist was used making that platform patternable, and (ii) attachment was done using oligonucleotides and DNA rather than just DNA which allows for the possibility of attaching one strand of DNA to two separate electrodes for DNA wire testing and applications.
