Substrate patterning and activation strategies for DNA chip fabrication

The immobilization of nucleic acids onto substrates in array fabrication is a complex process involving three major steps: (i) the chemical modification of the arrayed material in such a fashion that it can interact with complementary functionalities present on the substrate to form a stable bond; (ii) the coating of the support surface with adequate functional groups to allow specific binding and prevent nonspecific adsorption of the material to be arrayed; and (iii) the use of a delivery system that brings small quantities of the arrayed material to specific positions on the surface. Different types of nucleic acids or their analogues (cDNA, oligonucleotides or peptide nucleic acids), supports (silica, gold, polymeric membranes and gels), surface activation chemistries (organosilanes, thiols) and Patterning tools call be used for these purposes and will be described in this review.