Glass silanization with blocked isocyanates for the fabrication of DNA microarrays

Microarray glass slides were functionalized with isocyanate-gamma-propyltrimethoxysilane and characterized by atomic force microscopy, contact angle measurements. The coating was also tested in microarray DNA hybridization experiments using fluorescence microscopy for the detection of the spots. Isocyanate groups were blocked with both methyl ethyl ketoxime (MEKO) or bisulfite (BS). Contact angle measurements showed that BS blocking agent makes glass slide more hydrophilic than MEKO one likely because of the presence of ionic groups. Atomic force microscopy shows the presence of a continuous domain with some depressed areas that could be attributed to silanized and unmodified glass, respectively. Binding tests for amino-functionalized oligonucleotides did not evidence any difference between the two blocking systems. In contrast to these results, the hybridization efficiency of the two systems are different, since probes spotted on MEKO blocked slides show a fluorescence intensity which is about three times higher than those achieved with BS slides.