Imaging of Viral Genomic RNA Replication with Nanoprobes.

Viruses are a great threat to human life and health. Different viruses have its unique mechanism to efficiently infect cells, and the entry process and the nucleic acid replication using cell machine are two critical processes related to the fate of virus progeny. Real-time and long-term imaging techniques can be used to thoroughly investigate the viral infection events.

Chiral nanoprobes for targeting and long-term imaging of the Golgi apparatus.

The Golgi apparatus is an essential subcellular organelle. Targeting and monitoring the Golgi change at the single-cell level over a long time scale are critical but are challenges that have not yet been tackled. Inspired by the precise Golgi positioning ability of galactosyltransferase and protein kinase D, due to their cysteine residues, we developed a method for long-term Golgi imaging.

Surface-engineered quantum dots/electrospun nanofibers as a networked fluorescence aptasensing platform toward biomarkers.

A membrane-based fluorescent sensing platform is a facile, point-of-care and promising technique in chemo/bio-analytical fields. However, the existing fluorescence sensing films for cancer biomarkers have several problems, with dissatisfactory sensitivity and selectivity, low utilization of probes encapsulated in films as well as the tedious design of membrane structures. In this work, a novel fluorescence sensing platform is fabricated by bio-grafting quantum dots (QDs) onto the surface of electrospun nanofibers (NFs).

A dynamic cell entry pathway of respiratory syncytial virus revealed by tracking the quantum dot-labeled single virus.

Studying the cell entry pathway at the single-particle level can provide detailed and quantitative information for the dynamic events involved in virus entry. Indeed, the viral entry dynamics cannot be monitored by static staining methods used in cell biology, and thus virus dynamic tracking could be useful in the development of effective antiviral strategies. Therefore, the aim of this work was to use a quantum dot-based single-particle tracking approach to monitor the cell entry behavior of the respiratory syncytial virus (RSV) in living cells.

Color resolution improvement of the dark-field microscopy imaging of single light scattering plasmonic nanoprobes for microRNA visual detection.

Imaging of light scattering plasmonic nanoparticles (PNPs) with the aid of the dark-field microscopy imaging (iDFM) technique has attracted wide attention owing to its high signal-to-noise ratio, but to improve the color resolution and contrast of dark-field microscopy (DFM) images of single light scattering PNPs in a small spectral variation environment is still a challenge. In this study, a new color analytical method for resolving the resolution and contrast in DFM images has been developed and further applied for colorimetric analysis using the digital image processing technique. The color of single light scattering PNP images is automatically coded at first with the hue values of the HSI color model, and then amplified using the MATLAB program even for marginal spectral changes, leading to significant improvement of the color resolution of DFM images and easy detection with the naked eye.

His-tag based in situ labelling of progeny viruses for real-time single virus tracking in living cells.

Tracking virus infection events in live cells is useful for understanding the mechanism of virus infection, and fluorescent labelling is a critical step. Herein a noninvasive strategy for labelling viruses with His-tags was developed by in situ modifying the cell surface proteins with polypeptides containing His-tags during progeny virus assembly. The His-tagged viruses were further conjugated with Ni-nitrilotriacetate complex modified quantum dots, and retained their infectivity for real-time single virus tracking in living cells.

HSI colour-coded analysis of scattered light of single plasmonic nanoparticles.

Single plasmonic nanoparticles (PNPs) analysis with dark-field microscopic imaging (iDFM) has attracted much attention in recent years. The ability for quantitative analysis of iDFM is critical, but cumbersome, for characterizing and analyzing the scattered light of single PNPs. Here, a simple automatic HSI colour coding method is established for coding dark-field microscopic (DFM) images of single PNPs with localized surface plasmon resonance (LSPR) scattered light, showing that hue value in the HSI system can realize accurate quantitative analysis of iDFM and providing a novel approach for quantitative chemical and biochemical imaging at the single nanoparticle level.

A magnetic nanoparticle-based aptasensor for selective and sensitive determination of lysozyme with strongly scattering silver nanoparticles.

Qualitative and quantitative determination of lysozyme concentrations in urine and serum with high selectivity and sensitivity is important for diagnosing the progression of several diseases. In this report, we devised an improved method for specifically detecting lysozyme by combining magnetic nanoparticles (for separation and enrichment), an aptamer (for selective binding of lysozyme) and strongly scattering silver nanoparticles (AgNPs, for detection by light scattering, but also providing another level of selectivity due to their electrostatic binding with lysozyme). In this system, 0.

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.

Coomassie brilliant blue R-250 as a new surface-enhanced Raman scattering probe for prion protein through a dual-aptamer mechanism.

Surface-enhanced Raman scattering (SERS) spectra, which can provide large information about trace amount of chemical and biological species have been widely performed as a well-established tool in complex biological system. In this work, coomassie brilliant blue (R-250) with high affinity to proteins and high Raman activity was employed as a Raman reporter to probe prion protein (PrP) through a dual-aptamer mechanism, and thus an original strategy for PrP determination was proposed, which showed great potential to turn on the SERS response through specific recognition of anti-prion aptamers towards the target protein. Aptamers (Apt1 and Apt 2) recognizing distinct epitopes of PrP with high affinity were first conjugated to Ag@Si NPs, and Ag@Si-PrP/R-250-Ag@Si conjugates were obtained in the presence of PrP/R-250, inducing dramatically enhanced Raman signal.

Aptamer-mediated nanocomposites of semiconductor quantum dots and graphene oxide as well as their applications in intracellular imaging and targeted drug delivery.

Fluorescent semiconductor quantum dot-graphene oxide (QD-GO) nanocomposites with unique optical properties can be prepared by a facile decoration of aptamer-labelled CdSe@ZnS QDs on GO nanosheets. The formation of such nanocomposites is based on the π-π stacking between the DNA bases on the QD surfaces and the GO. TEM and AFM were used to study the morphologies and distribution of the QDs on the GO surfaces.

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.

Selective and sensitive colorimetric detection of stringent alarmone ppGpp with Fenton-like reagent.

Stringent alarmone, namely, guanosine 3'-diphosphate-5'-diphosphate (ppGpp), is a global regulator that plays a critical role in the survival, growth, metabolism, and many other vital processes of microorganisms. Because of its structural similarity to normal nucleotides, it is also a challenge for the selective and sensitive detection of ppGpp nowadays. Herein, we developed a colorimetric method for the selective detection of ppGpp by inhibiting the redox reaction between Fenton-like reagent (composed of Fe(3+) and H2O2) with 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS).

Real-time light scattering tracking of gold nanoparticles- bioconjugated respiratory syncytial virus infecting HEp-2 cells.

Real-time tracking of virus invasion is crucial for understanding viral infection mechanism, which, however, needs simple and efficient labeling chemistry with improved signal-to-noise ratio. For that purpose, herein we investigated the invasion dynamics of respiratory syncytial virus (RSV) through dark-field microscopic imaging (iDFM) technique by using Au nanoparticles (AuNPs) as light scattering labels. RSV, a ubiquitous, non-segmented, pleiomorphic and negative-sense RNA virus, is an important human pathogen in infants, the elderly, and the immunocompromised.

A general quantitative pH sensor developed with dicyandiamide N-doped high quantum yield graphene quantum dots.

A general quantitative pH sensor for environmental and intracellular applications was developed by the facile hydrothermal preparation of dicyandiamide (DCD) N-doped high quantum yield (QY) graphene quantum dots (GQDs) using citric acid (CA) as the carbon source. The obtained N-doped GQDs have excellent photoluminesence (PL) properties with a relatively high QY of 36.5%, suggesting that N-doped chemistry could promote the QY of carbon nanomaterials.

DNA-templated Ag nanoclusters as fluorescent probes for sensing and intracellular imaging of hydroxyl radicals.

We have developed a simple, rapid and label-free sensor for the essential biological OH radicals based on the fluorescence quenching of DNA-templated Ag nanoclusters (DNA-Ag NCs). The OH radicals generated from the Fenton reagent attack and cleave the DNA template, which disturbs the microenvironments around Ag NCs, resulting in spontaneous aggregation due to the lack of stabilization and further the quenching of the Ag NCs fluorescence. These changes in fluorescence intensity allow sensing of OH radicals with good sensitivity and selectivity under optimal conditions.

Metal-enhanced fluorescence of nano-core-shell structure used for sensitive detection of prion protein with a dual-aptamer strategy.

Metal-enhanced fluorescence (MEF) as a newly recognized technology is widespread throughout biological research. The use of fluorophore-metal interactions is recognized to be able to alleviate some of fluorophore photophysical constraints, favorably increase both the fluorophore emission intensity and photostability. In this contribution, we developed a novel metal-enhanced fluorescence (MEF) and dual-aptamer-based strategy to achieve the prion detection in solution and intracellular protein imaging simultaneously, which shows high promise for nanostructure-based biosensing.

A new type of pH-responsive coordination polymer sphere as a vehicle for targeted anticancer drug delivery and sustained release.

A new type of coordination polymer sphere prepared by combining 1,1'-(1,4-butanediyl)bis(imidazole) (bbi) and ferrous ions has been demonstrated as a targeted delivery system for in situ encapsulating anticancer drugs. These stable coordination polymer spheres can be fabricated simply by a deposition method. Drugs, doxorubicin hydrochloride (DOX·HCl) for example, can be easily in situ encapsulated by simply mixing the drug with bbi ligand through the deposition method and results in a high drug loading efficiency up to 98% and a drug loading content of nearly 40%, which is remarkably high for not only metal-organic but also other materials.