Perovskite Quantum Dots Supplier - Alfa Chemistry

PDDA Cd Quantum Dots

Product Description

Alfa Chemistry can provide customers with PDDA Cd quantum dots in the wavelength range of 450-665 nm. In this case, the surface of the polydiallyldimethylammonium chloride (PDDA) coated Cd-based quantum dots (QDs) do not contain any linkable reactive groups and exhibit a zeta potential of more than +50 mV. These positively charged quantum dots have applications in cell tracking.


ECL Immunosensor

The electrochemiluminescence (ECL) of CdSe quantum dots (QDs) is greatly enhanced by the binding of carbon nanotubes (CNTs) and poly(diallyldimethylammonium chloride) (PDDA) in CdSe QDs films and can be successfully used to develop sensitive ECL immunosensors for the detection of human IgG (Ag). The novel CdSe QDs-CNTs composites exhibit high ECL strength, good biocompatibility and high stability, which hold great promise for the fabrication of ECL biosensors with higher sensitivity. The ECL signal was significantly enhanced after conjugation of PDDA as a binding linker to the CdSe QDs-CNTs composite membrane on the electrode. Subsequently, gold nanoparticles (GNPs) assembled on the CdSe QDs-CNTs/PDDA-modified electrode could amplify the ECL signal again. The ECL immunosensor was successfully fabricated after immobilizing the antibody (Ab) on the electrode by GNPs. This is the first time that the unique features of PDDA-enhanced QDs ECL were explored and used to develop an ECL biosensor. The principle of ECL detection of target Ag is based on the increase of steric hindrance after the immune response, which leads to a decrease in ECL intensity. Silver concentrations were measured over a linear range of 0.002-500 ng L-1 with a detection limit of 0.6 pg mL-1.

The fabricating procedures for CdSe QDs–CNTs conjugates (A), and the ECL immunosensor (B).Fig. 1 The fabricating procedures for CdSe QDs–CNTs conjugates (A), and the ECL immunosensor (B). (Jie et al., 2009)

Photoelectrochemical Sensors

Liu et al. synthesized water-soluble hydrophobic acetic acid-modified pot sulfide (CdS) quantum dots using a simple method. CdS was modified onto steel tin oxide (ITO) electrodes by electrostatic adsorption with polydimethyldiallyl chlorinated bells (PDDA). In the presence of the electron donor triethanolamine (TEA), the CdS-modified ITO electrode has a stable anodic photocurrent. P-type semiconductor HgS formed by the in situ adsorption of Hg2+ on the surface of CdS forms a p-n junction with n-type semiconductor CdS, which can promote the electron-hole separation and charge transport, resulting in an increase in the photocurrent of CdS quantum dots. The effects of Cd,S molar ratio in the reaction precursor, pH of the reaction solution and reflux time on the interaction of the synthesized quantum dots with Hg2+ were investigated. In addition, the effects of pH of the electrolyte solution, applied voltage and reaction time on the photocurrent of Hg2+-enhanced CdS quantum dots were also investigated. Based on this, a photoelectrochemical sensor for sensitive detection of Hg2+ was constructed. The linear range of the sensor response to Hg2+ was 4.0x10-8~2.0x10-5 mol/L, the detection limit was 2.4x10-8 mol/L, and the recoveries were 98.3%~103.5%.

TEM image of TGA-capped CdS QDs.Fig. 2 TEM image of TGA-capped CdS QDs. (Liu et al., 2014)

Alfa Chemistry can provide a variety of complex and customized 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.


  1. Jie, G. , et al. Enhanced electrochemiluminescence of CdSe quantum dots composited with CNTs and PDDA for sensitive immunoassay[J]. Biosensors & Bioelectronics, 2009, 24(11):3352-3358.
  2. Liu, K. L. , et al. A Novel Photoelectrochemical Sensor for Hg~(2+) Detection Based on In-situ Formation of p-n Junction[J]. Journal of Instrumental Analysis, 2014.
* It should be noted that our service is only used for research, not for clinical use.


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