Novel strategy for designing tiny semiconductor particles for wide-ranging applications

MoS2 quantum dots synthesised with the new approach can potentially generate cancer-killing properties.


Engineers at the National University of Singapore (NUS) have developed a non-expensive and scalable way to synthesize transition metal dichalcogenides quantum dots (TMD QDs). This new strategy help engineers to alter the properties of TMD QDs specifically for different applications.

Engineers have developed a novel bottom-up synthesis strategy that can consistently construct TMD QDs of a specific size, a cheaper and more scalable method than the conventional top-down approach. The TMD QDs are synthesized by responding to progress metal oxides or chlorides with chalogen precursors under mild watery and room temperature conditions. Utilizing the bottom-up methodology, the group effectively incorporated a little library of seven TMD QDs and could modify their electronic and optical properties likewise.

Associate Professor David Leong from the Department of Chemical and Biomolecular Engineering at NUS Faculty of Engineering said, “Using the bottom-up approach to synthesize TMD QDs is like constructing a building from scratch using concrete, steel and glass component; it gives us full control over the design and features of the building.”

“Similarly, this bottom-up approach allows us to vary the ratio of transition metal ions and chalcogen ions in the reaction to synthesize the TMD QDs with the properties we desire. In addition, through our bottom-up approach, we are able to synthesize new TMD QDs that are not found naturally. They may have new properties that can lead to newer applications.”

Engineers synthesized MoS2 QDs to demonstrate proof-of-concept biomedical applications. Through their investigations, the group demonstrated that the defect properties of MoS2 QDs can be engineered with accuracy utilizing the bottom-up way to deal with create fluctuating dimensions of oxidative stress, and can along these lines be utilized for photodynamic therapy, a rising cancer growth treatment.

Assoc Prof Leong added, “Photodynamic therapy currently utilizes photosensitive organic compounds that produce oxidative stress to kill cancer cells. These organic compounds can remain in the body for a few days and patients receiving this kind of photodynamic therapy are advised against unnecessary exposure to bright light.”

“TMD QDs such as MoS2 QDs may offer a safer alternative to these organic compounds as some transition metals like Mo are themselves essential minerals and can be quickly metabolized after the photodynamic treatment. We will conduct further tests to verify this.”

“The potential of TMD QDs, however, goes far beyond just biomedical applications. Moving forward, the team is working on expanding its library of TMD QDs using the bottom-up strategy, and to optimize them for other applications such as the next generation TV and electronic device screens, advanced electronic components, and even solar cells.”

The findings of the study were published in prestigious scientific journal Nature Communications on 3 January 2019.

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