Hydrazide-containing bifunctional nanospheres were covalently coupled on the surface with IgG, avidin, and biotin, to generate novel fluorescent-magnetic-biotargeting trifunctional nanospheres, which can be used in a number of biomedical applications, including visual sorting and manipulation of apoptotic cells as demonstrated here.
Human respiratory tract epithelial cells are the portals of human infection with influenza viruses. However, the infection pathway of individual avian influenza viruses in human respiratory cells remains poorly reported so far. The single‐particle tracking technique (SPT) is a powerful tool for studying the transport mechanism of biomolecules in live cells. In this work, we use quantum dots to label avian influenza H9N2 virus and elaborate on the infection mechanism of the virus in human bronchial epithelial (HBE) cells using a three‐dimensional SPT technique. We have found that the H9N2 virus can infect HBE cells directly and the virus infection follows an actin filament‐ and microtubule‐dependent process with a three‐stage pattern. The transport behaviors show a high degree of consistency between the sialic acid receptors and the influenza virus. Real‐time SPT provides dynamic evidence of the sialic acid receptors‐related infection behavior of the avian influenza virus in live cells. The study of the influence of sialic acid receptors on virus infection may contribute to a better understanding of the cross‐species transmission of the avian influenza virus.
Nanoplastics, as a hot topic of novel contaminants, lack extensive concern in higher plants; especially the potential impact and mechanism of nanoplastics on legume crops remains elusive. In this study, the toxicity of polystyrene nanoplastics (PS-NPs, 200 nm) with diverse doses (control, 10, 50, 100, 200, 500 mg/L) to soybean and mung bean plants grown hydroponically for 7 d was investigated at both the macroscopic and molecular levels. The results demonstrated that the root length of both plants was markedly suppressed to varying degrees. Similarly, mineral elements (Fe, Zn) were notably decreased in soybean roots, consistent with Cu alteration in mung bean. Moreover, PS-NPs considerably elevated malondialdehyde (MDA) levels only in soybean roots. Enzyme activity data indicated mung bean exhibited significant damage only at higher doses of PS-NPs stress than soybean, implying mung bean is more resilient. Transcriptome analysis showed that PS-NPs stimulated the expression of genes associated with the antioxidant system in plant roots. Furthermore, starch and sucrose metabolism might play a key role in coping with PS-NPs to enhance soybean resistance, but the MAPK pathway was enriched in mung bean. Our findings provide valuable perspectives for an in-depth understanding of the performance of plants growing in waters contaminated by nanoplastics.
Exploring the virus infection mechanisms is significant for defending against virus infection and providing a basis for studying endocytosis mechanisms. Single-particle tracking technique is a powerful tool to monitor virus infection in real time for obtaining dynamic information. In this study, we reported a quantum-dot-based single-particle tracking technique to efficiently and globally research the virus infection behaviors in individual cells. It was observed that many influenza viruses were moving rapidly, converging to the microtubule organizing center (MTOC), interacting with acidic endosomes, and finally entering the target endosomes for genome release, which provides a vivid portrayal of the five-stage virus infection process. This report settles a long-pending question of how viruses move and interact with acidic endosomes before genome release in the perinuclear region and also finds that influenza virus infection is likely to be a "MTOC rescue" model for genome release. The systemic technique developed in this report is expected to be widely used for studying the mechanisms of virus infection and uncovering the secrets of endocytosis.
We herein used Ag2Se quantum dots (QDs) as a target-modulated sensitizer for upconversion nanoparticles (UCNPs) and the target thrombin as the sensitizing switch to construct a biosensor, circumventing the limited luminescence resonance energy transfer (LRET) efficiency of UCNPs, with enhanced signal-to-background ratio (SBR) and assay sensitivity.
Nanocarriers hold great promise for the controlled release of therapeutic payloads to target organs/tissues and extended duration of anticancer agents in the bloodstream. However, limited data on their in vivo pharmacokinetics and delivery process hamper clinical applications. Here we report a series of micellar nanocarriers self-assembled from new-generation thiophenthiadiazole (TTD)-based NIR-II fluorophores HLAnP (n = 1-4) for simultaneous bioimaging and drug delivery. The NIR-II HLA4P nanocarrier displays exceptional non-fouling performance, minimal immunogenicity, ultralong blood half-life, and high tumor accumulation even with different administration routes. When used as a drug carrier, HLA4P with encapsulated doxorubicin (DOX) realized accurate tumor targeting and continuous real-time in vivo NIR-II tracking of drug delivery and therapy, showing a sustained release rate, improved therapeutic effect, and diminished cardiotoxicity as compared to free DOX. This study provides a new perspective on the design of dual-functional NIR-II fluorophores for diagnostic and therapeutic applications.
Entry is the first critical step for the infection of influenza A virus and of great significance for the research and development of antiflu drugs. Influenza A virus depends on exploitation of cellular endocytosis to enter its host cells, and its entry behaviors in distinct routes still need further investigation. With the aid of a single-virus tracking technique and quantum dots, we have realized real-time and multicolor visualization of the endocytic process of individual viruses and comprehensive dissection of two distinct dynamin-dependent endocytic pathways of influenza A virus, either dependent on clathrin or not. Based on the sequential progression of protein recruitment and viral motility, we have revealed the asynchronization in the recruitments of clathrin and dynamin during clathrin-dependent entry of the virus, with a large population of events for short-lived recruitments of these two proteins being abortive. In addition, the differentiated durations of dynamin recruitment and responses to inhibitors in these two routes have evidenced somewhat different roles of dynamin. Besides promoting membrane fission in both entry routes, dynamin also participates in the maturation of a clathrin-coated pit in the clathrin-dependent route. Collectively, the current study displays a dynamic and precise image of the entry process of influenza A virus and elucidates the mechanisms of distinct entry routes. This quantum dot-based single-virus tracking technique is proven to be well-suited for investigating the choreographed interactions between virus and cellular proteins.
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