Surface functionalization studies and direct laser printing of oligonucleotides toward the fabrication of a micromembrane DNA capacitive biosensor

This work presents a comparative study between two functionalization techniques, gold (Au) and 3-glycidoxypropyl-tri-methoxy silane (GOPTS) that were used to immobilize thiol-modified oligonucleotides on low temperature oxide (LTO) on silicon (Si) surfaces toward the fabrication of a micromembrane array capacitive DNA biosensor. In the effort to increase the surface stress that develops upon probe immobilization and target hybridization and thus enhance the sensorʹs sensitivity, a number of parameters were investigated such as probe and target concentrations as well as the thickness and roughness of the functionalization layers. Our results indicate that GOPTS is better suited as a functionalization layer for the development of microcantilever or micromembrane-based biosensors due to the enhanced hybridization efficiencies achieved, its relative stability over time and the ability to regenerate the surfaces following analyte recognition. Furthermore, with the use of Laser Induced Forward Transfer, probe oligonucleotides were uniformly deposited at the micron scale on GOPTS-functionalized surfaces, thus allowing for the realization of a micromembrane array capacitive DNA biosensor.