Photomodulating RNA cleavage using photolabile circular antisense oligodeoxynucleotides

Caged antisense oligodeoxynucleotides (asODNs) are synthesized by linking two ends of linear oligodeoxynucleotides using a photocleavable linker. Two of them (H30 and H40) have hairpin-like structures which show a large difference in thermal stability (ΔTm = 17.5°C and 11.6°C) comparing to uncaged ones. The other three (C20, C30 and C40) without stable secondary structures have the middle 20 deoxynucleotides complementary to 40-mer RNA. All caged asODNs have restricted opening which provides control over RNA/asODN interaction. RNase H assay results showed that 40-mer RNA digestion could be photo-modulated 2- to 3-fold upon light-activation with H30, H40, C30 and C40, while with C20, RNA digestion was almost not detectable; however, photo-activation triggered >20-fold increase of RNA digestion. And gel shift assays showed that it needed >0.04 μM H40 and 0.5 μM H30 to completely bind 0.02 μM 40-mer RNA, and for C40 and C30, it needed >0.2 μM and 0.5 μM for 0.02 μM 40-mer RNA binding. However, even 4 μM C20 was not able to fully bind the same concentration of 40-mer RNA. By simple adjustment of ring size of caged asODNs, we could successfully photoregulate their hybridization with mRNA and target RNA hydrolysis by RNase H with light activation

Visualizing Fluoride Ion in Mitochondria and Lysosome of Living Cells and in Living Mice with Positively Charged Ratiometric Probes

Two ratiometric probes fluoride ion, <b>Mito-F</b> and <b>Lyso-F</b>, were rationally designed and synthesized with positive charges at physiological conditions. The positive charges functioned as target moieties for subcellular mitochondria and lysosome of living cells, and effective sequesters of fluoride ion for fast and efficient fluorescent detection. In addition, in vivo imaging of fluoride ion in living mice was successfully achieved for the first time using probe <b>Mito-F</b>

EFFECTS ANALYSIS OF PRESSURE ON THE MAGNETIC MEMORY SIGNALS OF PIPELINE DEFECTS

In order to analyze the feasibility of using magnetic memory testing technology to pipeline online inspection,it’s necessary to consider the effect of pressure on the pipeline defects magnetic memory signals. Based on the J-A force-magnetic coupling model a relationship between the relative permeability and stress was concluded. The relationship was imported in ANSYS software to carry out the co-simulation between mechanical and static magnetic. The results show that magnetic memory signals of defects have two characteristics—— radial magnetic field in the pipeline mutating from minimum to maximum and axial magnetic field appearing maximum. The magnetic field inside the pipeline decreases and defect’s magnetic memory signals decreases and then remains constant when the pressure increases. Magnetic memory testing technology can be used in pipeline online inspection

Photodegradable Polyesters for Triggered Release

Abstract: Photodegradable polyesters were synthesized with a photolabile monomer 2-nitrophenylethylene glycol and dioyl chlorides with different lengths. These polymers can be assembled to form polymeric particles with encapsulation of target substances. Light activation can degrade these particles and release payloads in both aqueous solutions and RAW 264.7 cells

Photoregulating RNA Digestion Using Azobenzene Linked Dumbbell Antisense Oligodeoxynucleotides

Introduction of 4,4′-bis­(hydroxymethyl)-azobenzene (azo) to dumbbell hairpin oligonucleotides at the loop position was able to reversibly control the stability of the whole hairpin structure via UV or visible light irradiation. Here, we designed and synthesized a series of azobenzene linked dumbbell antisense oligodeoxynucleotides (asODNs) containing two terminal hairpins that are composed of an asODN and a short inhibitory sense strand. Thermal melting studies of these azobenzene linked dumbbell asODNs indicated that efficient <i>trans</i> to <i>cis</i> photoisomerization of azobenzene moieties induced large difference in thermal stability (Δ<i>T</i>_m = 12.1–21.3 °C). In addition, photomodulation of their RNA binding abilities and RNA digestion by RNase H was investigated. The <i>trans</i>-azobenzene linked asODNs with the optimized base pairs between asODN strands and inhibitory sense strands could only bind few percentage of the target RNA, while it was able to recover their binding to the target RNA and degrade it by RNase H after light irradiation. Upon optimization, it is promising to use these azobenzene linked asODNs for reversible spatial and temporal regulation of antisense activities based on both steric binding and RNA digestion by RNase H

Quaternary Ammonium Promoted Ultra Selective and Sensitive Fluorescence Detection of Fluoride Ion in Water and Living Cells

Highly selective and sensitive fluorescent probes with a quaternary ammonium moiety have been rationally designed and developed for fast and sensitive fluorescence detection of fluoride ion (F^– from NaF, not TBAF) in aqueous solution and living cells. With the sequestration effect of quaternary ammonium, the detection time was less than 2 min and the detection limit of fluoride ion was as low as 0.57 ppm that is among the lowest detection limits in aqueous solutions of many fluoride fluorescence probes in the literature

Cholesterol-Modified Caged siRNAs for Photoregulating Exogenous and Endogenous Gene Expression

siRNA has been widely applied in research and drug development due to its sequence-specific gene silencing ability. However, how to spatiotemporally control its function is still one of its challenges. Light, a fast and noninvasive trigger, is a promising tool for spatiotemporal control of gene expression. Here, we designed and synthesized a new series of caged siRNAs modified with single cholesterol at the 5′ terminal of antisense strand RNA through a photolabile linker (Chol-PL-siRNAs). We demonstrated that these caged siRNAs were successfully used to photochemically regulate both exogenous (<i>firefly luciferase</i> and <i>gfp</i>) and endogenous gene expression (mitotic kinesin-5, <i>Eg5</i>) in cells