Stable silver nanoparticles–aptamer bioconjugates for cellular prion protein imaging

Combining the unique optical properties of metal nanoparticles and the specific recognition of aptamer,aptamer–nanoparticle conjugates have been extensively used in a wide range of applications,particularly multifunctional nanoparticles for cell detection and molecular imaging.Conventional conjugates prepared by chemisorption of monothiol-modified oligonucleotides onto nanoparticle surfaces suffer from a lack of stability when exposed to a variety of small molecules.If silver is used in place of gold,then this lack of stability is even more pronounced.In this study,we reported here the effective and facile strategy of preparing stable silver nanoparticle–aptamer conjugates by in situ generation of strong metal affinity capping ligands,dithiocarbamates modified anti-prion protein aptamer.The conjugates produced are stable and can withstand NaCl concentration at0.25 mol/L.Meanwhile,they could be applied in the cellular prion protein imaging successfully.     

基于水溶性共轭高分子构象效应的凝血酶检测

介绍了水溶性共轭高分子和核酸适体(aptamer)在生物传感检测中的应用.提出了一种基于aptamer和水溶性聚噻吩的构象效应进行凝血酶检测的比色方法.结果表明,该方法具有较高的选择性和灵敏度,肉眼目测最低可检测63 nM凝血酶.     

Inhibition of hepatitis C virus internal ribosome entry site-mediated translation by an RNA targeting the conserved IIIf domain

Hepatitis C virus (HCV) translation initiation depends on an internal ribosome entry site (IRES). We previously identified an RNA molecule (HH363–10) able to bind and cleave the HCV IRES region. This paper characterizes its capacity to interfere with IRES function. Inhibition assays showed that it blocks IRES activity both in vitro and in a human hepatoma cell line. Although nucleotides involved in binding and cleavage reside in separate regions of the inhibitor HH363–10, further analysis demonstrated the strongest effect to be an intrinsic feature of the entire molecule; the abolishment of either of the two activities resulted in a reduction in its function. Probing assays demonstrate that HH363–10 specifically interacts with the conserved IIIf domain of the pseudoknot structure in the IRES, leading to the inhibition of the formation of translationally competent 80S particles. The combination of two inhibitory activities targeting different sequences in a chimeric molecule may be a good strategy to avoid the emergence of resistant viral variants. Received 26 July 2007; received after revision 24 September 2007; accepted 26 September 2007     

Aptamers against prion proteins and prions

Prion diseases are fatal neurodegenerative and infectious disorders of humans and animals, characterized by structural transition of the host-encoded cellular prion protein (PrP^c) into the aberrantly folded pathologic isoform PrP^Sc. RNA, DNA or peptide aptamers are classes of molecules which can be selected from complex combinatorial libraries for high affinity and specific binding to prion proteins and which might therefore be useful in diagnosis and therapy of prion diseases. Nucleic acid aptamers, which can be chemically synthesized, stabilized and immobilized, appear more suitable for diagnostic purposes, allowing use of PrP^Sc as selection target. Peptide aptamers facilitate appropriate intracellular expression, targeting and re-routing without losing their binding properties to PrP, a requirement for potential therapeutic gene transfer experiments in vivo. Elucidation of structural properties of peptide aptamers might be used as basis for rational drug design, providing another attractive application of peptide aptamers in the search for effective anti-prion strategies.     

Near-infrared fluorescent aptamer-templated silver nanoclusters facilely synthesized for cellular imaging applications

Fluorescent metal nanoclusters(NCs)have received extensive attention for their potential uses in bionanotechnology.Here,we develop a facile strategy to synthesize near-infrared fluorescent silver nanoclusters(Ag NCs)stabilized by MUC1 aptamer.The MUC1-Ag NCs are characterized by UV–Vis absorption spectroscopy,fluorescence spectroscopy,transmission electron microscopy,and fluorescence lifetime.These results indicated that the MUC1-Ag NCs possess bright near-infrared luminescence,high stability,and excellent biocompatibility.The cellular imaging of MUC1-Ag NCs by confocal laser microscopy demonstrated them to be promising candidates as novel fluorescent probes for biomedical application.