Cd-based Core/shell Quantum Dots with Streptavidin
Alfa Chemistry offers quantum dots with strong lattice strength and stable performance. The internal pressure caused by the lattice defects of the quantum dots is effectively reduced, so the quantum dots have high luminescence efficiency and stability. Alfa Chemistry can provide customers with Cd-based core/shell quantum dots with streptavidin in the emission spectral range from 450 nm to 580 nm, with excellent chemical and optical stability, good quality stability and high quantum yield.
A one-dimensional plasma grating is a resonant electromagnetic wave absorber with characteristic wavelengths. The study focuses on one-dimensional plasma gratings fabricated from poly(glycidyl methacrylate) (PGMA) brushes and CdS quantum dots (CdQDs), as well as line arrays with PGMA chains grafted onto the host substrate by immobilizing biotin-modified CdQDs. Plasma gratings with PGMA brush line arrays (PBLA) exhibit absorption at 441 nm, while CdQDs immobilized on CdQDs on PBLA exhibit characteristic absorbance at 396 nm. The blue shift at 441 nm matches the absorption peak of the biotin-modified CdQDs, resulting in enhanced photoluminescence emission from the CdQDs. Incubation of 50 nM CdQDs assembled with streptavidin resulted in a significant decrease in grating height leading to a redshift of the absorbance peak to 536 nm. The intensity of PL emission gradually decreased with increasing streptavidin concentration due to the deviation in absorbance. In addition, the results of Lin et al. showed that the incubation of streptavidin also changed the color reflected from the surface due to an effective change in the refractive index of the layer as well. The detection limit of the grating for streptavidin was determined to be 50 nM. Thus, PBLA-CdQD has the potential to be used as a highly sensitive, label-free optical biosensor.
Fig. 1 Schematic illustration of the immobilization of CdQDs on PBLA on a surface. (Lin et al., 2019)
A simple aqueous synthesis of silica-coated highly fluorescent CdTe quantum dots was developed by Wolcott et al. CdTe quantum dots have the advantage that their emission can be tuned to the near-infrared region where tissue absorption is minimal, while the silica shell prevents leakage of toxic Cd2+ and provides a surface that is easy to bind to biomolecules such as proteins. Transmission electron microscopy and atomic force microscopy measurements have confirmed the presence of silica shells with thicknesses of 2-5 nm. Photoluminescence studies have shown that the silica shells lead to a significant increase in photostability in tris-borate-ethylenediaminetetraacetate and phosphate buffers. To further improve their biocompatibility, the silica-capped QDs were functionalized with polyethylene glycol and thiol-terminated bioconjugates. By using these linkers, the antibody proteins were successfully linked together. Streptavidin-maleimide and biotinylated polystyrene microbeads confirmed the biological activity and conjugation specificity of the thiolated QDs. These functionalized silica-capped QDs are ideal labels that are easy to synthesize, robust, safe, and readily bind to biomolecules while maintaining bioactivity. They have many potential uses in biolabeling and imaging.
Fig.2 Streptavidin-QD-biotinylated microbead pictures under white light (left) and UV illumination (right) on an ethanol-cleaned glass slide. (Wolcott et al., 2006)
Alfa Chemistry can provide a variety of complex and customized fluorescent quantum dot products. Our products involve perovskites precursors, perovskites quantum dots, quantum dot kit, single layer quantum dots, upconverting nanoparticles and other fluorescent quantum dots. Alfa Chemistry provides products with high fluorescence quantum yield, stable quality and relatively low price. Our products are constantly updated. If the product you need is not in our catalog, please feel free to contact us, we provide relevant custom services.
- Lin, Feng-Ping, et al. Surface lattice resonance of line array of poly (glycidyl methacrylate) with CdS quantum dots for label-free biosensing[J]. Colloids and Surfaces B: Biointerfaces, 2019, 179: 199-207.
- Wolcott, Abraham, et al. Silica-coated CdTe quantum dots functionalized with thiols for bioconjugation to IgG proteins[J]. The Journal of Physical Chemistry B, 2006, 110(11): 5779-5789.
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