Semiconductor quantum dots as fluorescent probes for in vitro and in vivo bio-molecular and cellular imaging

Abstract

Over the years, biological imaging has seen many advances, allowing scientists to unfold many of the mysteries surrounding biological processes. The ideal imaging resolution would be in nanometres, as most biological processes occur at this scale. Nanotechnology has made this possible with functionalised nanoparticles that can bind to specific targets and trace processes at the cellular and molecular level. Quantum dots (QDs) or semiconductor nanocrystals are luminescent particles that have the potential to be the next generation fluorophores. This paper is an overview of the basics of QDs and their role as fluorescent probes for various biological imaging applications. Their potential clinical applications and the limitations that need to be overcome have also been discussed.

Toxicity assessment of repeated intravenous injections of arginine–glycine–aspartic acid peptide conjugated CdSeTe/ZnS quantum dots in mice

“…1,2 Quantum dots (QDs) with unique optical properties are a class of novel nanomaterials and have been widely used in medical research. 3,4 QDs are nanocrystals (diameter ranges from 2-10 nm) consisting of elements belonging to group 2-6 or group 3-5. When coated with water-soluble bioactive material, they form core-shell nanostructures that are water soluble and biocompatible.…”

Near-infrared quantum dots for HER2 localization and imaging of cancer cells

“…For example, QDs can potentially be used as agents for photodynamic therapy in the management of cancer, when conjugated with photoactive dyes that can be activated with light to generate free radicals leading to localized cell death. 15 Bioconjugated targeted NIR-QDs visible in deep tissues would be ideal for this purpose because they would accumulate at the site of the cancer which can then be ablated by light activation under image guidance.…”

“…15 QDs can be size-tuned to emit at near-infrared (NIR, 650-1,000 nm) wavelengths, which are ideal for deep tissue imaging because the biological window is transparent to these wavelengths. This is based on the fact that tissue chromophores like hemoglobin absorb light in the visible spectrum (400-700 nm), leading to scattering, diffraction, and poor penetration through the skin.…”

Advances in the application of nanotechnology in the diagnosis and treatment of gastrointestinal tumors

“…Another potential problem with using QDs in vivo is whether injection poses a toxic risk. Modifications have been made to decrease potential toxicity; however, further research is required to determine appropriate clinical adaptability (26). As cadmium ions released from the QDs are associated with cytotoxicity, polyethylene glycol (PEG) was developed to reduced the toxicity of uncoated QDs.…”