![]() ![]() 15 A newer design strategy, presented by the labs of Chen 16 and Tang 17,18 has involved linking the 5′ and 3′ ends with a photocleavable moiety. 15 In this example, MO-mRNA hybridization was sterically blocked until the caging groups were released from the nucleobases. subsequently presented caged MOs where multiple caged nucleotide monomers were incorporated during solid-phase synthesis. 14 employed a complementary sense strand and photocleavable linker. 7 Initial caged antisense oligos from our lab, 8–10 the Chen lab, 11–13 and Tomasini et al. Synthetic challenges of site-specifically incorporating one or more photolabile moieties within a large oligonucleotide, and limitations arising from the available organic caging moieties, have slowed such development.Ī particular focus for caged oligo development has been antisense morpholinos (MOs), which are commonly used to block mRNA translation and modify pre-mRNA splicing in a variety of model organisms, including mouse, zebrafish, frog, sea urchin, and chick. Less investigated are caged oligonucleotides, despite the central roles played by DNA and RNA in biology and the tantalizing potential for being able to turn genes “on” or “off” with light. 6 In each case, photoactivation with high spatiotemporal control can be achieved using a focused laser beam of suitable wavelength. 1 More generally, “caged” molecules, 2 whose latent biological activity can be revealed with light, have been widely adopted, particularly for the study of amino acids, 3 peptides, 4 neurotransmitters, 5 and metal ions. For example, channelrhodopsin-a single component, light-activated cation channel protein from algae-was co-opted in the development of optogenetic approaches for manipulating the activity of specific neurons and controlling animal behaviour. Introduction Photochemical methods for regulating the structure, function, and/or localization of molecular species enable the manipulation of advanced materials ( e.g., silicon computer chips) as well as complex biological systems. As demonstrated, Ru photolinkers provide a versatile method for controlling structure and function of biopolymers. One-cell-stage zebrafish embryos microinjected with Ru-MO and incubated in the dark for 24 h developed normally, consistent with caging, whereas irradiation at 450 nm dissociated one 3-ethynylpyridine ligand ( Φ = 0.33) and uncaged the MO to achieve gene knockdown. RuBEP-caged circular morpholinos (Ru-MOs) targeting two early developmental zebrafish genes, chordin and notail, were synthesized and tested in vivo. Here, we present the first example of a visible light responsive ruthenium-based photolinker, Ru(bipyridine) 2(3-ethynylpyridine) 2 (RuBEP), which was reacted stoichiometrically with a 25mer DNA or morpholino (MO) oligonucleotide functionalized with 3′ and 5′ terminal azides, via Cu( I)-mediated Huisgen cycloaddition reactions. Photochemical approaches afford high spatiotemporal control over molecular structure and function, for broad applications in materials and biological science. ![]()
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