Core/shell Quantum Dots
Core/shell quantum dots are the product of further engineering in quantum dot (QD) structures. Due to the shell surrounding the core of QDs, they exhibit better optical properties than simple QDs, leading to improved stability and photoluminescence efficiency. QDs have a high surface area-to-volume ratio, and there are unsaturated or dangling bonds on the surface. These undercoordinated atoms make them more active than atoms in most QD materials. Coating QDs with appropriate materials to form core/shell QDs enables them to exhibit higher quantum yields and higher stability than core QDs; the growth of the shell both limits the excitation of the core and protects the core from Oxidation and chemical degradation.
Alfa Chemistry offers a variety of core-shell quantum dots, both oil-soluble and water-soluble. Including CdSeS/ZnS alloyed Quantum Dots, CdSeTe/ZnS Quantum Dots, CdTe/CdSe/ZnS Quantum Dots, Cu:ZnCdS/ZnS Quantum Dots, Cu:ZnlnS/ZnS Quantum Dots, CulnS/ZnS Quantum Dot, Mn Doped Quantum Dots , ZnSe/ZnS Quantum Dots, CdZnS/ZnS Quantum Dots, etc., the wavelength range is 460-850 nm.
Core/shell quantum dots have various applications in various industrial fields including lasers, light-emitting diodes, and photovoltaic devices. Core/shell quantum dots can also be used in biological applications because they are less toxic than uncoated quantum dots.
Solid-phase Luminescence Sensor
Novel solid-phase luminescence sensors (SPLS) based on molecularly imprinted polymers (MIPs) as recognition elements and semiconducting CdSeS/ZnS alloy quantum dots (QDs) as phosphors have been synthesized and developed for the determination of sulfadiazine. Surface-modified quantum dots are attached to the surface of the glass sheet. MIPs and non-imprinted polymers (NIPs) with sulfadiazine (SSZ) recognition sites were synthesized and attached to immobilized QDs. Ahmadpour et al. used fluorescence spectroscopy to determine trace amounts of sulfadiazine, which is based on the quenching effect of sulfadiazine on the emission of QDs and the fluorescence resonance energy transfer (FRET) mechanism. Compared with the NIP-QDs-based sensor, the MIP-QDs-based sensor showed high recognition ability for sulfadiazine. Various experimental parameters affecting the fluorescence intensity such as reaction time and pH were studied and optimized. Under optimal conditions, the MIP-QDs sensor exhibited good linearity for sulfadiazine in the range of 0.02-1.5 µmol L-1 with a coefficient of determination (R2) of 0.9986. The detection limit (S/N=3) and quantification limit (S/N=10) were 0.0071 and 0.024 µmol L-1, respectively.
Fig. 1 Schematic illustration of the synthesis procedure of fluorescence MIP-QDs-glass slide sensor. (Ahmadpour et al., 2019)
Mohamed et al. can well prepare bright, near-infrared (NIR) emission by direct incorporation of as-prepared hydrophobic CuInS2/ZnS quantum dots (QDs) into lipophilic silane micelles followed by the formation of stable CuInS2/ZnS@SiO2 nanoparticles. The obtained CuInS2/ZnS@SiO2 nanoparticles uniformly contain single-core and multi-core prominent CuInS2/ZnS quantum dots, while the silica shell thickness can be controlled within 5-10 nm, and the overall size is 17-25 nm. Furthermore, functionalized CuInS2/ZnS quantum dots encapsulated in silica spheres accelerated their bioconjugation to holographic transferrin (Tf) for further cancer cell imaging. CuInS2/ZnS@SiO2 nanoparticles not only show dominant near-infrared band-edge luminescence at 650-720 nm, quantum yields (QY) between 30% and 50%, and no recognized photoluminescence (PL) red shift , and exhibited excellent PL and colloidal stability in aqueous media.
Fig.2 Schematic illustration of the silica coating procedures for single-core hydrophobic CuInS2/ZnS QDs. (Mohamed et al., 2011)
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.
- Ahmadpour, Hamidreza, and Seyed Mohamadreza Milani Hosseini. A solid-phase luminescence sensor based on molecularly imprinted polymer-CdSeS/ZnS quantum dots for selective extraction and detection of sulfasalazine in biological samples[J]. Talanta, 2019, 194: 534-541.
- Mohamed, et al. Biocompatible and Highly Luminescent Near-Infrared CuInS2/ZnS Quantum Dots Embedded Silica Beads for Cancer Cell Imaging[J]. ACS Applied Materials & Interfaces, 2014, 6(3):2011-2017.
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