Categorization of Quantum Dots, Clusters, Nanoclusters, and Nanodots

Abstract

Recently, various studies related to the photophysical properties of various nanoscale and subnanoscale particles have been actively carried out in the chemical and biological fields. However, the terminology of these nanoparticles has not been clearly defined, which causes confusion among research groups and students. This article aims to clarify the definitions of four terms: quantum dots (QDs), nanodots (NDs), nanoclusters (NCs), and clusters. The historical usage of these terms and research trends over the last five years will be presented. On the basis of the size and photophysical properties of these particles, we propose clear and transferrable definitions that can be used across multiple disciplines.

Detection of Lead(II) in Living Cells by Inducing the Transformation of a Supramolecular System into Quantum Dots

“…These particles showed strong fluorescence emission in LSCM (Figure b). These results indicated that under the control of the H–G–S supramolecular system, the S 2– was not leached into the solution and Pb 2+ could not form PbS precipitates with S 2– ; however, Pb 2+ bound to S 2– in the H–G–S supramolecular system to in situ form nanocrystals, which induces the in situ transformation of H–G–S nanorods into PbS QDs. , Meanwhile, the obtained PbS QDs complexed with H–G . The unexpected strong bright blue fluorescence emission at 475 nm is emitted from the H–G –PbS QD complexes because in certain conditions when PbS QDs form a complex with other organic compounds, they could emit visible fluorescence under suitable exciting lights. , …”

“…These results indicated that under the control of the H−G−S supramolecular system, the S 2− was not leached into the solution and Pb 2+ could not form PbS precipitates with S 2− ; however, Pb 2+ bound to S 2− in the H−G−S supramolecular system to in situ form nanocrystals, which induces the in situ transformation of H−G−S nanorods into PbS QDs. 57,58 Meanwhile, the obtained PbS QDs complexed with H−G.…”

Assessing the environmental effects related to quantum dot structure, function, synthesis and exposure

“…The term, "quantum dots", was initially used to describe zerodimensional, metallic semiconductor nanoparticles with quantum confinement, which is the change in optical properties directly related to nanoparticle diameter. 1,2 Currently, QDs refer to small-sized (typically 2-20 nm) fluorescent metallic and non-metallic nanoparticles (e.g., carbon-based) that possess quantum confinement effects 3,4 (Fig. 1).…”

Semiconductor clusters: Synthetic precursors for colloidal quantum dots

“…Semiconductor clusters have been identified as reaction intermediates in the formation of CQDs. They contain tens to hundreds of inorganic atoms, where the surface is coordinated with molecular ligands (Park et al, 2021). Their unique photophysical properties originate from smaller entities than conventional CQDs, which have recently intrigued this field of study.…”