One-step immobilization of aminated and thiolated DNA onto poly(methylmethacrylate) (PMMA) substrates

Direct immobilisation of modified DNA oligonucleotides (aminated or thiolated) onto a plastic substrate, poly(methylmethacrylate), (PMMA) is described. Using the methyl esters present on non-modified PMMA, it was possible to establish a covalent bond between the electron donor of a DNA probe and the C terminal ester of the PMMA substrate. Since the procedure consists of a single brief wash in isopropanol or ethanol, the procedure is simple and environmentally friendly. The new immobilization strategy was characterized by analysing DNA microarray performance. The new procedure resulted in probe- and hybridization densities that were greater or equivalent to those obtained with commercially available surfaces and other procedures to immobilize DNA onto PMMA. The described chemistry selectively immobilized the DNA via terminal thiol or amine groups indicating that probe orientation could be controlled. Furthermore, the chemical bond between the immobilized DNA and the PMMA could endure repeated heat cycling with only 50% probe loss after 20 cycles, indicating that the chemistry could be used in integrated PCR/microarray devices.