Anion Binding and Sensing Using Cs124-Sensitized Luminescent Terbium Complexes

Two terbium complexes with varying degrees of intramolecular coordination, Tb:DO2A-Cs124 and Tb:DOTA-Cs124, were prepared. Their capacity to detect biologically and environmentally relevant anions through their luminescence changes was investigated. Tb:DOTA-Cs124 demonstrated exceptional selectivity as a sensor for nitrite, while Tb:DO2A-Cs124 detects nitrite, phosphates, and a range of carboxylate-containing anions

Method For Determination Of Singlet Oxygen Quantum Yields For New Fluorene-based Photosensitizers In Aqueous Media For The Advancement Of Photodynamic Therapy

Photodynamic therapy (PDT) has been investigated over the past three decades and is currently an approved therapeutic modality for skin cancer, the treatment of superficial bladder, early lung and advanced esophageal cancers, and age-related macular degeneration in a number of countries. In PDT, the absorption of light by a chromophore generates cytotoxic species such as reactive singlet oxygen, leading to irreversible destruction of the treated tissue. The measurement of the singlet oxygen quantum yield is an important determinant used to evaluate the efficiency of new photodynamic therapy agents developed in the laboratory, to screen potential photosensitizers in aqueous media.The singlet oxygen quantum yield is a quantitative measurement of the efficiency in which photosensitizers are able to use energy, in the form of light, to convert oxygen in the ground state to the reactive species singlet oxygen useful in photodynamic therapy. Singlet oxygen quantum yields of photosensitizers differ when measured in different solvents. The majority of the existing quantum yield values found in literature for various photosensitizers are documented with the sensitizers in organic solvents though values in aqueous media are more valuable for actual applications. Determination of accurate and precise quantum yield values in aqueous solution is a much more difficult problem than in organic media. Problems in aqueous solution arise primarily from the physicochemical properties of singlet oxygen in water. Singlet oxygen has a much shorter lifetime in water than it does in organic solvents, causing challenges with respect to quantitative detection of singlet oxygen.The ensuing pages are an attempt to explore the theory and document the procedures developed to provide the accurate measurement of singlet oxygen in aqueous media. Details of this experimental method and singlet oxygen quantum yield results of new compounds relative to established photosensitizers will be presented

CCDC 629369: Experimental Crystal Structure Determination

Related Article: S.C.Kettwich, S.N.Pierson, A.J.Peloquin, J.M.Mabry, S.T.Iacono|2012|New J.Chem.|36|941|doi:10.1039/c2nj20922e,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.,Related Article: S.T.Iacono, A.Vij, W.Grabow, D.W.Smith Junior, J.M.Mabry|2007|Chem.Commun.||4992|doi:10.1039/b712976

CCDC 642077: Experimental Crystal Structure Determination

Related Article: S.C.Kettwich, S.N.Pierson, A.J.Peloquin, J.M.Mabry, S.T.Iacono|2012|New J.Chem.|36|941|doi:10.1039/c2nj20922e,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.,Related Article: S.T.Iacono, A.Vij, W.Grabow, D.W.Smith Junior, J.M.Mabry|2007|Chem.Commun.||4992|doi:10.1039/b712976

Optimization of the Split-Spinach Aptamer for Monitoring Nanoparticle Assembly Involving Multiple Contiguous RNAs

The fact that structural RNA motifs can direct RNAs to fold and self-assemble into predictable pre-defined structures is an attractive quality and driving force for RNA’s use in nanotechnology. RNA’s recognized diversity concerning cellular and synthetically selected functionalities, however, help explain why it continues to draw attention for new nano-applications. Herein, we report the modification of a bifurcated reporter system based on the previously documented Spinach aptamer/DFHBI fluorophore pair that affords the ability to confirm the assembly of contiguous RNA strands within the context of the previously reported multi-stranded RNA nanoring. Exploration of the sequence space associated with the base pairs flanking the aptamer core demonstrate that fluorescent feedback can be optimized to minimize the fluorescence associated with partially-assembled RNA nanorings. Finally, we demonstrate that the aptamer-integrated nanoring is capable of assembling directly from transcribed DNA in one pot

Fluorescent Monitoring of RNA Assembly and Processing Using the Split-Spinach Aptamer

As insights into RNA’s many diverse cellular roles continue to be gained, interest and applications in RNA self-assembly and dynamics remain at the forefront of structural biology. The bifurcation of functional molecules into nonfunctional fragments provides a useful strategy for controlling and monitoring cellular RNA processes and functionalities. Herein we present the bifurcation of the preexisting Spinach aptamer and demonstrate its utility as a novel split aptamer system for monitoring RNA self-assembly as well as the processing of pre-short interfering substrates. We show for the first time that the Spinach aptamer can be divided into two nonfunctional halves that, once assembled, restore the original fluorescent signal characteristic of the unabridged aptamer. In this regard, the split-Spinach aptamer is represented as a potential tool for monitoring the self-assembly of artificial and/or natural RNAs

Co-transcriptional Assembly of Chemically Modified RNA Nanoparticles Functionalized with siRNAs

We report a generalized methodology for the one-pot production of chemically modified functional RNA nanoparticles during in vitro transcription with T7 RNA polymerase. The efficiency of incorporation of 2′-fluoro-dNTP in the transcripts by the wild type T7 RNA polymerase dramatically increases in the presence of manganese ions, resulting in a high-yield production of chemically modified RNA nanoparticles functionalized with siRNAs that are resistant to nucleases from human blood serum. Moreover, the unpurified transcription mixture can be used for functional ex vivo pilot experiments