Photoactivated immobilization of single-stranded DNAs on a psoralen-functionalized surface under low pH conditions

摘要

Single stranded DNA was photo-patterned on a psoralen-functionalized surface and conjugated with a psoralen-modified enzyme. Photoreactions between the single-stranded DNA and psoralen-functionalized materials were found to be significantaly influenced by pH, showing high efficientcy only under acidic conditions. Specifically, the photopatter-ing of single-stranded DNA probes, such as polythy-mine, polyadenine, polycytosine, and polyguanine, on a psoralen-functionalized amino-dextran surface under various pH conditions (pH 3.36-8.80) showed that the polythymine probes had the highest immobilization efficiency at pH 3.36. The effect of pH was further confirmed by photopatterning the single-stranded DNA probes using the photomask. While almost no pattern was observed on the psoralen surface at pHs greater than 5.5, much more visible patterns were observed as the pH was decreased below 5.5. As a result of the irradiation of polyT_(15) and polyA_(15)-labeled DNA probes, the photopatterns formed by the irradiation of polythymine probes were found to be associated with the cross-linking between the thymine and the psoralen moieties. Finally, additional studies show- ed that psoralen could be used as the reactive center in the photo-induced cross-linking reaction between DNA and the model protein, horseradish peroxidase (HRP).