1,721,004 research outputs found
Can nanotechnology improve cancer diagnosis through miRNA detection?
Full text linkmiRNAs are key regulators of gene expression, and alterations in their expression levels correlate with the onset and progression of cancer. Although miRNAs have been proposed as biomarkers for cancer diagnosis, their application in routine clinical praxis is yet to come. Current quantification strategies have limitation, and there is a great interest in developing innovative ones. Since a few years, nanotechnology-based approaches for miRNA quantification are emerging at fast pace but there is urgent need to go beyond the proof-of-concept stage. Nanotechnology will have a strong impact on cancer diagnosis through miRNA detection only if it is demonstrated that the newly developed approaches are indeed working on 'real-world' samples under standardized conditions
Nucleic acid enzymes
No full textSince the discovery of the first natural ribozyme more than 20 years ago, it has become clear that nucleic acids are not only the static depository of genetic information, but also possess intriguing catalytic activity. The number of reactions catalyzed by engineered nucleic acid enzymes is growing continuously. The versatility of these catalysts supports the idea of an ancestral world based on RNA predating the emergence of proteins, and also drives many studies towards practical applications for nucleic acid enzymes
Efficient preparation of organic substrate-RNA conjugates via in vitro transcription
No full textA concise synthetic way has been developed for the preparation of guanosine monophosphate derivatives carrying a decaethylene glycol spacer at their 5'-oxygen to which are attached a range of organic substrates. The four different compounds, prepared via a convergent synthetic strategy, carry a tethered benzylallyl ether residue (1a), an anthracene (1b), a benzyl carbamate residue (1c), or a primary amino group (1d), respectively. All four compounds have been successfully incorporated at the T-end of a 25-mer long RNA transcript via T7 RNA polymerase, and no inhibition of chain elongation could be observed. Under proper conditions, 1a and 1b can be incorporated up to 90-95% and 1c up to 68%. The amino-terminated initiator Id is incorporated less efficiently although still up to 49%. These results show that the more hydrophobic the guanosine monophosphate derivative is, the higher is its enzymatic incorporation
Toward an artificial metallo-ribozyme: Enantioselective allylic substitution by a DNA-diene-iridium hybrid catalyst
No full textNo abstrac
Quantification and reactivity of functional groups in the ligand shell of PEGylated gold nanoparticles via a fluorescence-based assay
No full textWe present a fluorescence-based assay for the characterization of functionalized gold nanoparticles (AuNPs) capped with a self-assembled monolayer of mixed thiols derived from poly(ethylene glycol) (PEG). These water-soluble AuNPs carry primary amino groups at the solvent-exposed interface, which can be used for further conjugation of biologically active molecules. The reported assay allows quantification of the average number of functionalizable amino groups per particle (NNH2) with a relative uncertainty below or equal to ±14% (95% confidence interval), thus providing essential information for the successive derivatization of the AuNPs. Here, a fluorescently labeled derivative of peptide-neurotoxin conantokin-G was coupled to the amino groups of the particle ligand shell via a flexible linker. We quantitatively determined the average number of peptides per particle (Npept) and the yield of the two-step conjugation strategy. AuNPs carrying 50−70 copies of the peptide were obtained. In addition, we have gained insights into the deterioration of the self-assembled monolayer due to thiol desorption with time. Under ordinary storage conditions in solution and at room temperature, a decrease in NNH2 between 48% and 75% could be observed at the end of the period of investigation (42−56 days). Slow desorption of the conjugated peptides upon storage was also observed and quantified (∼25% in 14 days)
DNA-based phosphane ligands
No full textIn order to expand the repertoire of DNA sequences specifically interacting with transition metals, we report here the first examples of DNA sequences carrying mono- and bidentate phosphane ligands as well as P,N-ligands. Aminoalkyl-modified oligonucleotides have been reacted at predetermined internal sites with carboxylate derivatives of pyrphos, BINAP and phosphinooxazoline (PHOX) 2b-d. Carbodiimide coupling in the presence of N-hydroxysuccinimide provided the DNA-ligand conjugates in 38-78% yield. Phosphane-containing oligonucleotides and their phosphane sulfide analogues were characterized by mass spectrometry (MALDI-TOF and FT-ICR-ESI) and their stability after purification and isolation was systematically investigated. While DNA-appended pyrphos ligand was quickly oxidized, BINAP and PHOX conjugates showed high stabilities, making them useful precursors for incorporation of transition metals into DNA
Allylic Amination by a DNA-Diene-Iridium(I) Hybrid Catalyst
No full textDNA hybrid catalysis goes organometallic: A DNA strand functionalized with diene ligands forms iridium(I) complexes that can efficiently catalyze an allylic amination in aqueous medium (see scheme). The DNA-based complexes show high stability and activity, and their secondary structure influences the stereoselectivity of the reaction
Highly stable cage-like complexes by self-assembly of tetracationic Zn(II) porphyrinates and tetrasulfonatocalix 4 arenes in polar solvents
Full text linkTetracationic Zn(II) porphyrinates and tetraanionic calix[4]arenes can be assembled in polar solvents to obtain cage-like complexes in an entropy driven process. These structures are remarkably stable even in the presence of water or competing salts
Synthetic self-assembled models with biomimetic functions
Full text linkSelf-assembly can be considered a powerful tool in the hand of chemists for the understanding, modeling and mimicking of biological systems. The possibility of reproducing biological functions in synthetic systems obtained by self-assembly is envisioned as a modest but very important step towards the understanding of the mystery of life and its emergence on Earth
- …
