Streptavidin-conjugated Qd
Streptavidin-conjugated Qd - Related Videos
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Cited by 4 •
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We present a novel and powerful integration of nanophotonics (QD-FRET) and microfluidics to investigate the formation of polyelectrolyte polyplexes, which is expected to provide better control and synthesis of uniform and customizable polyplexes for future nucleic acid-based therapeutics.
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Analyzing Influenza Virus Internalization Using a Streptavidin Blocking Assay
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2026
Source: Pohl, M. O. & Stertz, S. Measuring Attachment and Internalization of Influenza A Virus in A549 Cells by Flow Cytometry. J. Vis. Exp. (2015)This video demonstrates the use of a streptavidin blocking assay to distinguish surface-bound from internalized influenza virus in human lung epithelial cells. Comparing fluorescence signals shows that a higher intensity after incubation indicates successful viral internalization.
02:46
Visualizing Dose-Dependent Spike Protein Uptake with Quantum Dot Conjugates
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2026
Source: Tran, B. N., et. al. High-throughput Confocal Imaging of Quantum Dot-Conjugated SARS-CoV-2 Spike Trimers to Track Binding and Endocytosis in HEK293T Cells. J. Vis. Exp. (2022)This video demonstrates the use of quantum dot–conjugated spike protein (QD-Spike) to visualize dose-dependent viral entry in ACE2-GFP–expressing cells. Confocal imaging captures the internalization of QD-Spike via receptor-mediated endocytosis, modeling early coronavirus entry.
02:50
Conjugated Proteins
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2020
Simple proteins and protein complexes contain only amino acids. In contrast, many other proteins, called conjugated proteins, covalently bond with non-protein moieties. Nucleoproteins are protein complexes that contain nucleic acids, categorized as deoxyribonucleoproteins (DNPs) or ribonucleoproteins (RNPs) respectively. The nucleosome is a typical example of a DNP where nuclear DNA is associated with histone proteins. The major antigen for the Covid-19 virus SARS-CoV is an RNP that is critical...
13:06
Solubilization and Bio-conjugation of Quantum Dots and Bacterial Toxicity Assays by Growth Curve and Plate Count
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Cited by 7 •
2012
Nanoparticles such as semiconductor quantum dots (QDs) can be used to create photoactivatable agents for anti-microbial or anti-cancer applications. This technique shows how to water-solubilize cadmium telluride (CdTe) QDs, conjugate them to an antibiotic, and perform a bacterial inhibition assay based upon growth curves and plate count.
FAQs
Specificity comes from the biotin–streptavidin interaction at the probe surface. A biotinylated antibody, protein, or other targeting molecule attaches through this affinity link, positioning the fluorescent QD near the selected target. In immunology and infection studies, the targeting molecule determines what is labeled, whereas the QD supplies the optical signal used to visualize that label.
Emission wavelength is a key design variable because quantum dots can produce different fluorescent signals. Using probes with distinct emission wavelengths allows several targets to be analyzed in the same sample, provided each targeting molecule is directed toward a different antigen, pathogen, or cellular marker. This multiplexing improves simultaneous spatial and phenotypic characterization.
Photostability helps preserve fluorescence during observation, making labeled targets easier to detect and compare in complex samples. Combined with bright emission, this property supports visualization of cellular structures, microbial targets, and immune markers without the signal rapidly diminishing during microscopy. More persistent fluorescence can therefore strengthen spatial analysis of host–microbe interactions.
A basic workflow begins by selecting a biotinylated antibody, protein, or other targeting molecule suited to the antigen, pathogen, or cellular marker of interest. The targeting molecule binds streptavidin on the QD surface, and the resulting probe is applied to the sample. Fluorescence detection then reveals the location of the selected target.
Researchers can use these probes when they need to visualize antigens, pathogens, immune-cell markers, or interactions between host and microbe. Their bright, photostable fluorescence and tunable emission support analysis in complex samples, while multiple emission wavelengths can facilitate simultaneous examination of several biological targets within the same experimental setting.
The approach can provide both spatial and phenotypic information. Spatial readouts show where labeled antigens, microbes, or immune-cell markers occur, while phenotypic characterization distinguishes samples according to the combination of detected targets. This makes the probes useful for examining how cellular and microbial features are arranged and associated in complex biological specimens.
In diagnostic assays, fluorescence from the QD can reveal selected targets after biotinylated recognition molecules bind them through streptavidin. In host–microbe research, the same strategy helps visualize microbial targets alongside immune-cell markers or other cellular features. Using distinct emission wavelengths can extend these analyses to several targets and clarify their spatial relationships.