Perovskite Quantum Dots Supplier - Alfa Chemistry

PbS Quantum Dot End-capping Services


PbS capping technology refers to the wet chemical synthesis of Pb QDs, such as L-methionine (Meth), using different biomolecules as capping agents. The biomolecule can coordinate with metal ions or metal oxides in various ways. At the same time, Meth can be effectively used as a stabilizer to produce nanostructures with controllable size and shape. Methylated PbS QDs can be well dispersed in water and show strong fluorescence emission and high quantum yield.

Schematic of the aqueous synthesis of Meth-capped PbS QDsSchematic of the aqueous synthesis of Meth-capped PbS QDs (Rahimi et al. 2021)

How does capping technology work?

The surface chemical properties of quantum dots can be changed by the modification of the end of quantum dots, which can be applied in different fields according to the different surface ligands. L-methionine (Meth) is one of the amino acids containing sulfur and is almost always found on the interior of proteins. It contains several reactive groups (e.g., -SCH3, -NH2, and –COOH) that can act as electron donors for effective chelation with metal ions. In the first step, Pb2+ ions can be covered with the Meth capping agent and form a stable complex with a protective layer on the nano-particles surface. Next, the sulfide ion starts to bond with the capped metal ion forming PbS QDs precursor, with visual indication of PbS QDs nucleation with changing color, from white to brown color. Finally, when additional energy (heat) is applied, the reaction boosts up and QDs sizes grow. Furthermore, by using methionine (amino acid) as a capping agent, PbS QDs can be synthesized at pH = 8.0, which is close to the physiological pH. This is very significant for both biomedical and environmental applications.

Available Services

Alfa Chemistry offers comprehensive quantum dots modification services to meet any research need. Our scientific team is dedicated to helping our customers choose and optimize the quantum dots, as well as modification approach for each project. Our services include, but are not limited to the following:

  • End-capping of PbS Quantum Dots
  • Capping of other Quantum Dots (CdS, CdTe/ZnS, CdS/ ZnS and so on)

Advantages of End-capping Technology Services

  • State-of-the-art techniques and a wealth of successful experience.
  • Guaranteed quality, quantity, purity, and consistency.
  • Scalable platform and customized services for specific needs.
  • Fast turnaround time and competitive price.

Quality assurance and control

As a supplier of quantum dots, Alfa chemistry have a great deal of experience and product quality assurance system, starting from the quality of products, relying on advanced instruments and technology, to bring customers reliable products.

Standard Service Process

Standard Service Process

  • Email us with your requirements
  • Plan and experiment according to your needs
  • We will monitor the quality of the products you need to ensure that your requirements can be met
  • After ensuring the quality, we will carry out mass production to meet your demand
  • Finally, we deliver our products to our customers

Alfa Chemistry provides comprehensive and flexible quantum dots and quantum dot modification services. Our innovative techniques coupled with our large collection of products allow us to tackle your project to save your time and effort. If you require any further information, please feel free to contact us. We look forward to working together to meet your goals.

* It should be noted that our service is only used for research, not for clinical use.


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