Dansyl, a fluorescent photoprotecting group for microarray applications

BACKGROUND: The fluorescence dye 5-dimethylamino-1-naphthalenesulfonyl chloride (Dansyl chloride) is commonly used for labeling the N-terminus of proteins and peptides. Apart from the fluorescence, the -SO 2-NH-bonds formed are susceptible to photolytic cleavage and will subsequently restore free amines. Consequently, Dansyl amides could act as a fluorescent photoprotecting group with novel application in solid phase synthesis or in microarray technologies. RESULTS: Commercial microscope glass slides were silanized with (3-aminopropyl) triethoxysilane, exposed amines were activated with 1,4-phenylene diisothiocyanate and subsequently reacted with dansylated polyethylene imine (PEI). The resulting fluorescence of the surface was determined and used as a measure of the homogeneity of the introduced functional groups. Using a mask, Dansyl-PEI modified slides were locally exposed to photolytic cleavage within irradiation energy of 100 J cm -2. Inscribed structures would be easily recognized due to their loss of fluorescence. The restored amines in deprotected areas were reacted with phosphorylated capture oligonucleotides followed by hybridization with complementary Cy5-labeled targets. CONCLUSIONS: Capture probes immobilized precisely in structures exposed to UV-light while non-irradiated areas remained blocked. Such pre-structured surfaces allow the production of highly reproducible microarrays without any specific problems of spotting imperfections. Gridding and segmentation of the determined sample allocation facilitate spot finding and spot analysis.