Search

Genetically encoded molecular tools are crucial for live cell RNA imaging, and few are available for endogenous RNA imaging. We develop a new genetically encoded sensor using conformation switching RNA induced fluorogenic proteins that enable multicolor and signal-amplified imaging of endogenous RNAs. The sensor system is designed with an RNA sensing module and a degron-fused fluorescent protein reporter. Target RNA induces conformation switching of the RNA sensing module to form RNA aptamers that stabilize the degron-fused protein for fluorogenic imaging. This sensor is demonstrated for high-contrast imaging of survivin mRNA abundance and dynamics in live cells. Moreover, the sensor system is extended to a multicolor palette by screening fluorogenic proteins of distinct colors, and engineered into a signal amplifier using the split fluorescent protein design. The sensor is further exploited for imaging lncRNA MALAT-1 and its translocation dynamics during mitosis. Our sensor system can afford a valuable platform for RNA imaging in biomedical research and clinical theranostics.

The development of functional materials with nanometer-scale architectures and the effect of these architectures on their chemical and physical properties are currently of great interest in materials design. Polymerizable lyotropic liquid crystal (LLC) assemblies provide a facile entry into this area by allowing one to fix the inherent order in these systems using covalent bonds to create robust, nanostructured materials. The use of the cross-linked inverted hexagonal phase in templated nanocomposite formation and heterogeneous catalysis has been demonstrated. Additionally, the polymerization of LLC mesogens in the regular hexagonal and bicontinuous cubic phases is being targeted for future developments in functional materials. Future directions for new applications of these materials are also discussed.

A simple and efficient method for the synthesis of lactose-based homopolymers from N-lactosyl-N‘-(4-vinylbenzyl)urea or N‘-lactosyl-N,N-methyl(4-vinylbenzyl)urea (5a, 5b) is described. Free radical...

α,ω-Bis-4(vinylbenzyl) ethers of mono-, di-, tetra-, and hexa(ethylene glycol) were used as cross-linkers in polystyrene beads to examine the influence of glycol tether length and % incorporation upon polymer swelling and reagent diffusion. Swelling of 2, 10, and 20% cross-linked poly{styrene-co-[oligo(ethylene glycol) bis(4-vinylbenzyl)ether]} (PS−PEG) beads was determined to be higher or comparable to 2% cross-linked poly[styrene-co-divinylbenzene] (2% PS−DVB) beads. Fluorescence quenching of polymer-bound dansyl groups by Et3O·BF4 indicated that the most rapid intraresin diffusion of this electrophilic reagent occurred in toluene. PS−PEG beads exhibited faster quenching than 2% PS−DVB in poor swelling solvents but were slower to quench than 2% PS−DVB in toluene.

A simple and efficient method for the synthesis of lactose-based homopolymers from lactose O-(p-vinylbenzyl)oxime (4) is described. Free radical polymerization of the new oxime monomers proceeded smoothly in an aqueous solution using potassium persulfate (KPS) and N,N,N‘,N‘-tetramethylethylenediamine (TMEDA) as the initiating system and gave water-soluble homopolymers in good yields. These synthetic lactose-based polymers had high molecular weights and narrow polydispersities (Mw/Mn: 1.20−1.35) as determined by size exclusion chromatography, in conjunction with multiangle laser light scattering (SEC−MALLS). The Mark−Houwink equation was obtained as [η] = 2.15 × 10-4Mv0.73. When the monomer was copolymerized with the cross-linking reagent N,N‘-methylenebis(acrylamide) (BisA) (16% mol), hydrogels were formed which swelled as much as 21-fold in deionized water. These gels have potential applications as biocompatible materials.

Several taper-shaped, Bronsted acidic amphiphiles containing an amide linkage near the headgroup were synthesized with the goal of generating acidic, inverted hexagonal (HII) lyotropic liquid crystal (LLC) phases that can be stabilized by polymerization. These polymerizable acidic amphiphiles were synthesized by reacting the acyl chloride of 3,4,5-tris(11‘-acryloxyundecyloxy)benzoic acid with several amino acids (l-alanine, β-alanine, l-phenylalanine) and 2-aminoethanesulfonic acid. Of these derivatives, only the l-alanine derivative (1) was found to form the HII phase, using N,N-dimethylformamide as the hydrophilic solvent. To our knowledge, this is one of the rare examples (if not the only example) of a Bronsted acidic amphiphile capable of forming a high-curvature LLC phase. Monomer 1 was also found to be able to direct the formation of the other amide-containing acidic derivatives into the HII phase when blended together. IR analysis revealed that intermolecular amide H-bonding near the headgroup play...

A nanostructured, polymer-supported Sc(III) catalyst for heterogeneous Lewis acid catalysis in water was prepared by quantitative Sc(III) exchange of a cross-linked inverted hexagonal assembly containing sodium sulfonate groups. The material was found to catalyze Mukaiyama aldol and Mannich reactions with a syn/anti product ratio of ca. 2/1, whereas Sc(III) catalysts in solution and on amorphous polymer supports do not show any significant syn/anti diastereoselectivity under similar conditions.