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.
Enzyme-linked immunosorbent assay(ELISA)provides a convenient way for the detection of viral pathogens.However,conventional ELISA performed on mirowell plates suffers from poor sensitivity,laborious coating and complicated blocking procedures.Herein,we designed a sensitive colorimetric immunoassay by taking advantages of the enrichment and isolation ability of magnetic beads(MBs)and the high loading capacity of gold nanoparticles(AuNPs)for detecting respiratory syncytial virus(RSV)as a pathogen model.RSV was selectively captured and preconcentrated from samples with antibodies functionalized MBs,followed by binding with antibodies labeled AuNPs,which carrying a large amount of alkaline phosphatase(ALP)molecules for colorimetric signal amplification by catalyzing the dephosphorylation of non-colored pNPP to generate colored product pNP.After optimizing the experimental conditions based on the principle of low nonspecific signal,low cost,and high sensitivity,the analytical sensitivity of the developed immunoassay can be improved to 0.27 pg/mL,which is over sevenfold higher than that of commercially available RSV ELISA kits(2 pg/mL).In addition,the total assay time was less than 2.5 h without any pretreatment,which is much more rapid than other reported assays.Therefore,the proposed immunoassay holds great promise for the fabrication of rapid,sensitive,and economic method for the viral pathogen detection.
A new type of highly selective aptamer-labeled fluorescent silica nanoparticles[Apt-tris(2,20-bipyridyl)ruthenium(II)@SiO2NPs]were prepared through the reverse microemulsion method by using prolonged fluorescence lifetime ruthenium complexes of tris(2,20-bipyridyl)ruthenium(II)(Ru(bpy)32?)as the source of the fluorescence for cellular prion protein imaging.Investigations showed that the newly prepared Ru(bpy)32?@SiO2NPs possessed superior advantages of strong fluorescence,low toxicity,and easy surface modification for bioconjugation.Cell imaging experiments indicated that AptRu(bpy)32?@SiO2NPs had great tendency to human bone marrow neuroblastoma cells(SK-N-SH cells),since they can express large amount of prion protein on the surface of the cell,while in HeLa cells this phenomenon disappeared for the reason that HeLa cells cannot express prion proteins.
Wei WangXiao Li YanLei ZhanFei LengXiao Xi YangCheng Zhi Huang
Many recent exciting discoveries have revealed the versatility of RNAs and their importance in a variety of cellular functions which are strongly coupled to RNA structures. To understand the functions of RNAs, some structure prediction models have been developed in recent years. In this review, the progress in computational models for RNA structure prediction is introduced and the distinguishing features of many outstanding algorithms are discussed, emphasizing three- dimensional （3D） structure prediction. A promising coarse-grained model for predicting RNA 3D structure, stability and salt effect is also introduced briefly. Finally, we discuss the major challenges in the RNA 3D structure modeling.
A novel sensitive semi-quantitative virus detection technique was developed using the respiratory syncytial virus(RSV) as an example, through dark-field light scattering imaging of the surface state of the virusinvaded host cells. In this method, anti-RSV-antibody modified gold nanoparticles(Au NPs) could bind with the invading virus on the cell membrane of the infected host cells through the specific antibody-antigen binding. Then,the host cells could be imaged by the localized surface plasmon resonance light scattering properties of Au NPs under a dark-field light scattering microscopy, which could be further used to semi-quantify the invading virus.
