Biotinylated photocleavable polyethylenimine: capture and triggered release of nucleic acids from solid supports

A biotinylated photocleavable polyethylenimine (B-PC-PEI) was designed and synthesized for the capture and controlled release of nucleic acids from solid supports. B-PC-PEI was synthesized via a three-step reaction process and verified by 1H NMR and mass spectrometry. In aqueous solution, the o-nitrobenzyl group within B-PC-PEI was efficiently cleaved by 5 min of 365 nm light exposure from a distance of 20 cm (9 mW/cm2). When coupled to streptavidin-coated beads, the PEI domain of Cy5-labeled B-PC-PEI was released by 365 nm light exposure. In contrast, a Cy5-labeled biotinylated PEI (B-PEI) was used as a control and negligible fluorescence loss was observed. Cy5-labeled siRNA was electrostatically captured to streptavidin-coated beads preabsorbed with B-PC-PEI or B-PEI, and flow cytometry demonstrated significant loss of fluorescence from the bead surface after 5 min of light exposure only for B-PC-PEI, demonstrating controlled release of siRNA from the bead surface. Finally, the release of the Cy5-labeled siRNA into the supernatant was quantified. The release of Cy5-siRNA into the supernatant was significantly greater after 5 min of light exposure for B-PC-PEI/streptavidin beads compared to 0 min exposure and remained unchanged for B-PEI/streptavidin beads. B-PC-PEI facilitates capture and triggered release of surface-tethered nucleic acids with light exposure and is fully compatible with streptavidin-based applications.