Water-soluble CdTe/ZnS/CdS Quantum Dots
Product Description
CdTe/ZnS/CdS core-shell quantum dots have thorough ZnS and CdS shell material around CdTe core nanocrystals with emission in the range of 520 nm to 620 nm and 2 mg/mL in water. Quantum dots (QDs) are unique nanocrystalline semiconductors whose electronic and optical properties depend on the size and shape of the dots. The diameter of these particles can range from about 2-10 nm and the small size of the particles gives them a high surface-to-volume ratio, so their properties are intermediate between those of individual molecules and bulk semiconductors.
Features
High surface-to-volume ratio
Small size of the particles
Broad absorption spectrum
Applications
Photoluminescence (PL) Sensors
Photoluminescence (PL) sensors of quantum dots (QDs) are difficult to achieve accurate detection in sample waters. Wang et al. built a ratiometric PL sensor by using polyvinyl alcohol (PVA) CdTe/ZnS/CdS QDs and fluorescein isothiocyanate (FITC) fluorophores. In combination with the PL electronic eye of a homemade smartphone, precise detection of Cd2+ can be achieved. PVA was used to connect the QDs and FITC fluorophores without unnecessary ligand exchange and purification. For QDs fluorophores, ethylenediaminetetraacetic acid (EDTA) is used on their surface to induce specific Cd2+ recognition sites. The change in PL can be visualized as a color change on the smartphone as the Cd2+ concentration increases. the R/G ratio is linear with Cd2+ concentration in the range of 1-2000 µg/L, with LOD as low as 0.057 µg/L (S/N). The PL ratio method using PL E-eye is portable, fast, visible and highly selective compared to conventional analytical methods, especially in distinguishing Cd2+ from Zn2+.
Fig. 1 (a) Synthesis of the QDs nanocomposites (FPQ) with CdTe/ZnS/CdS QDs and FITC. (b) Process for detecting Cd2+ with FPQ and PL E-eye. (c) A smartphone-based portable instrument named PL E-eye. (Wang et al., 2020)
Fluorescence Sensor
Heavy metal pollution in the aqueous environment has an increasingly serious impact on human health and the environment, especially cadmium ions (Cd2+). Quantum dots (QDs) are a kind of inorganic fluorophores with unique optical and electrical properties. Wang et al. creatively proposed to combine PVA with CdTe/ZnS/CdS QDs and FITC fluorophores to form stable nanocomposites (FPQ). PVA is a biodegradable hydrophilic polymer that can easily interact with QDs without unnecessary ligand exchange. FPQ is then added to ethylenediaminetetraacetic acid (EDTA) solutions, causing PL quenching due to the creation of specific Cd2+ recognition sites. These sites can then be recognized by the addition of Cd2+ with PL recovery. During this process, the PL of FITC remains essentially unchanged for reference purposes.
Fig.2 (a)Synthesis of the FPQ nanocomposites. (b)Schematic view of Cd2+ detection with FPQ. (Wang et al., 2020)
Alfa Chemistry can provide a variety of complex and customized core-shell fluorescent quantum dot products. Our products involve a variety of fluorescent quantum dot products. 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.
References
- Wang, X. , et al. A QDs Nanocomposites-Based Photoluminescence Ratiometric Method for Selective and Visual Cadmium Detection Combining with Smartphone-Based PL E-Eye[J]. Journal of The Electrochemical Society, 2020, 167(14):147520.
- He, Y. , et al. Microwave Synthesis of Water-Dispersed CdTe/CdS/ZnS Core-Shell-Shell Quantum Dots with Excellent Photostability and Biocompatibility[J]. Advanced Materials, 2008.
- Wang, X. , et al. A QDs Nanocomposites-Based Ratiometric Fluorescence Sensor for Detection of Trace Cadmium Ions[J]. ECS Meeting Abstracts, 2020, MA2020-01(27):1986-1986.
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