New quantum dot study reveals implications for biological imaging

Graphic abstract. Credit: Nano-letters (2022). DOI: 10.1021/acs.nanolett.2c03563

A new study involving researchers at the University of Illinois at Chicago has taken an important step in the synthesis of multifunctional photonic nanomaterials.

In an article published in the journal Nano-letters, they report the synthesis of “giant” core-shell semiconductor quantum dots with record emissive lifetimes. Additionally, lifetimes can be adjusted by making a simple change to the internal structure of the material.

The group, which included collaborators from Princeton University and Pennsylvania State University, demonstrated a new structure-property concept that confers the ability to spatially locate electrons or holes in a core/shell heterostructure by adjusting the kinetic energy of the charge carrier to a parabolic potential energy surface. .

According to UIC chemist Preston Snee, this separation of charge carriers results in extended radiative lifetimes and continuous emission at the single nanoparticle level.

“These properties enable new applications for optics, facilitate new approaches such as timed single-particle imaging, and create breakthroughs for the development of other new advanced materials,” said Snee, associate professor of chemistry at UIC. and co-lead author of the study.

Snee and the study’s first author, Marcell Pálmai, a UIC postdoctoral research associate in chemistry, teamed up with Princeton’s Haw Yang and others to excite the quantum dot particle with light to put it into the exciton state. The exciton is an electron/hole charge pair, and in new materials, the electron travels from the center to the shell, where it is trapped for more than 500 nanoseconds, which is the record for such nanomaterials.

“As emissive materials, quantum dots promise to create more energy-efficient displays and can be used as fluorescent probes for biomedical research due to their very robust optical properties. They are 10 to 100 times more absorbent than dyes organic and are almost impervious to photobleaching, which is why they are used in the new Samsung QLED-TV,” they write.

These new particles have great efficacy for basic biological discovery, the researchers say.

The quantum dots presented in their paper emit at red wavelengths, which minimizes scattering, while the long lifetimes allow biological imaging to be performed with less background noise. At the single-particle level, the new quantum dots emit continuously, so a researcher can label cancer-relevant proteins and track biological dynamics without losing signal trace, which is currently a common problem with many such studies.

In future research, the group plans to demonstrate that the materials make good components for optical devices such as microscale lasers.