Dextran-Functionalized Super-nanoparticle Assemblies of Quantum Dots for Enhanced Cellular Immunolabeling and Imaging

Area of Science:

• Nanotechnology
• Biotechnology
• Materials Science

Background:

• Colloidal semiconductor quantum dots (QDs) are widely used in bioanalysis and imaging.
• Higher brightness materials are needed for advanced applications.
• Assembling individual QDs into super-nanoparticle (super-NP) structures can increase brightness.

Purpose of the Study:

• To develop and characterize dextran-functionalized super-NP assemblies of QDs (super-QDs).
• To evaluate the utility of super-QDs for bioimaging, particularly in overcoming smartphone-based imaging limitations.

Main Methods:

• Synthesized amphiphilic dextran for encapsulating hydrophobic QDs.
• Utilized an emulsion-based method to form super-QD assemblies.
• Characterized super-QDs at ensemble and single-particle levels.
• Conjugated antibodies using tetrameric antibody complexes (TACs) for cellular labeling.

Main Results:

• Super-QD assemblies (90-160 nm hydrodynamic diameter) exhibited orders-of-magnitude higher brightness and were non-blinking compared to individual QDs.
• Prepared super-QDs in RGB colors, including difficult-to-achieve shades like magenta.
• Demonstrated successful cellular immunolabeling and imaging using both epifluorescence microscopy and a smartphone platform.
• Super-QDs enhanced imaging performance on the smartphone platform, overcoming its technical limitations.

Conclusions:

• Dextran-functionalized super-QDs are a highly promising material for bioanalysis and imaging.
• The superior brightness of super-QDs is crucial for applications demanding high sensitivity.
• Super-QDs enable advanced bioimaging, even with resource-limited platforms like smartphones.