Sensitive detection of respiratory syncytial virus based on a dual signal amplified plasmonic enzyme-linked immunosorbent assay.

The timely detection of infectious pathogen is critical in clinical early diagnosis and treatment of infectious diseases. Plasmonic enzyme-linked immunosorbent assay (ELISA), by means of enzyme-mediated growth or aggregation of AuNPs, has received considerable attention because it allows a naked-eye detection of target in very low numbers. In this work, a dual-signal amplified plasmonic ELISA combined the high loading capacity of magnetic beads with the establishing stimulation effect of zinc ion has been developed to detect RSV as a model pathogen based on alkaline phosphatase-triggered dispersion of aggregated AuNPs. In ideal conditions, the proposed immunoassay can conveniently distinguish the concentration of RSV in a range of 0.1-30 pg/mL. In addition, the limit of detection of RSV of this immunoassay exceeds that of conventional ELISA by about 50 times. The high sensitivity makes this approach a good alternative to existing colorimetric immunoassays for pathogen detection.

Label-free and selective sensing of uric acid with gold nanoclusters as optical probe.

Clinically, the amount of uric acid (UA) in biological fluids is closely related to some diseases such as hyperuricemia and gout, thus it is of great significance to sense UA in clinical samples. In this work, red gold nanoclusters (AuNCs) with relatively high fluorescence quantum yield and strong fluorescence emission were facilely available using bovine serum albumin (BSA) as template. The fluorescence of BSA-protected AuNCs can be sensitively quenched by H2O2, which is further capable of sensing UA through the specific catalytic oxidation with uricase, since it generates stoichiometric quantity of H2O2 by-product. The proposed assay allows for the selective detection of UA in the range of 10-800 µM with a detection limit of 6.6 µM, which is applicable to sense UA in clinical samples with satisfactory results, suggesting its great potential for diagnostic purposes.

DNA-AuNP networks on cell membranes as a protective barrier to inhibit viral attachment, entry and budding.

Viral infections have caused numerous diseases and deaths worldwide. Due to the emergence of new viruses and frequent virus variation, conventional antiviral strategies that directly target viral or cellular proteins are limited because of the specificity, drug resistance and rapid clearance from the human body. Therefore, developing safe and potent antiviral agents with activity against viral infection at multiple points in the viral life cycle remains a major challenge. In this report, we propose a new modality to inhibit viral infection by fabricating DNA conjugated gold nanoparticle (DNA-AuNP) networks on cell membranes as a protective barrier. The DNA-AuNPs networks were found, via a plaque formation assay and viral titers, to have potent antiviral ability and protect host cells from human respiratory syncytial virus (RSV). Confocal immunofluorescence image analysis showed 80 ± 3.8% of viral attachment, 91.1 ± 0.9% of viral entry and 87.9 ± 2.8% of viral budding were inhibited by the DNA-AuNP networks, which were further confirmed by real-time fluorescence imaging of the RSV infection process. The antiviral activity of the networks may be attributed to steric effects, the disruption of membrane glycoproteins and limited fusion of cell membrane bilayers, all of which play important roles in viral infection. Therefore, our results suggest that the DNA-AuNP networks have not only prophylactic effects to inhibit virus attachment and entry, but also therapeutic effects to inhibit viral budding and cell-to-cell spread. More importantly, this proof-of-principle study provides a pathway for the development of a universal, broad-spectrum antiviral therapy.

In situ labelling chemistry of respiratory syncytial viruses by employing the biotinylated host-cell membrane protein for tracking the early stage of virus entry.

An in situ labelling strategy was proposed to produce quantum dot-labelled respiratory syncytial viruses (RSVs) by incorporating the biotinylated membrane protein of the host cells into mature virions, followed by conjugation with streptavidin modified quantum dots (SA-QDs), which has the advantages such as convenience, efficiency and minor influence on viral infectivity and thus could be successfully applied to track the early stage of virus entry.

A colorimetric immunoassay for respiratory syncytial virus detection based on gold nanoparticles-graphene oxide hybrids with mercury-enhanced peroxidase-like activity.

A novel colorimetric immunoassay for highly sensitive detection of respiratory syncytial virus (RSV), one of the leading causes of severe lower respiratory tract infections in all age groups, has been proposed based on Hg(2+)-stimulated peroxidase-like activity of gold nanoparticles-graphene oxide (AuNPs-GO) hybrids. This metal ion-enhanced immunoassay shows high promise in the field of biomedical sciences.

A surfactant-assisted redox hydrothermal route to prepare highly photoluminescent carbon quantum dots with aggregation-induced emission enhancement properties.

Highly PL carbon quantum dots (CQDs) were successfully prepared from C60 by introducing CTAB and H2O2 in aqueous NaOH under hydrothermal conditions. The CQDs displayed a nanoparticle aggregation-induced emission enhancement (NP-AIEE).