Compact quantum dot surface modification to enable emergent behaviors in quantum dot-DNA composites

Area of Science:

• Nanotechnology
• Bioconjugation Chemistry
• Materials Science

Background:

• Quantum dots (QDs) require surface modification with single-stranded DNA (ssDNA) for biological imaging, sensing, and photonic applications.
• Current ssDNA-QD conjugation methods face limitations including thick coatings, poor control over labeling density, and reduced stability.
• Developing stable and compact ssDNA-QD conjugates is crucial for advanced DNA-based nanodevices.

Purpose of the Study:

• To develop a robust and controlled method for ssDNA conjugation to QDs.
• To enhance the stability of ssDNA-QDs across a wide pH range and high ionic strength.
• To enable the integration of ssDNA-QDs into higher-order DNA nanostructures for photonic applications.

Main Methods:

• Combined thin, multidentate phytochelatin-3 (PC3) QD passivation with strain-promoted copper-free alkyne-azide click chemistry.
• Applied the method to various QD sizes (540-600 nm), ssDNA lengths (10-16 base pairs), and sequences.
• Evaluated fluorescence quenching efficiency upon hybridization with ssDNA-functionalized gold nanoparticles (AuNPs).

Main Results:

• Achieved stable ssDNA-QD conjugates with compact coatings across diverse QD and ssDNA parameters.
• Demonstrated high fluorescence quenching efficiency (up to 89%) with complementary ssDNA-AuNPs.
• Successfully incorporated the functionalized ssDNA-QDs into DNA origami nanostructures.

Conclusions:

• The PC3 passivation and click chemistry approach provides a versatile and effective strategy for creating stable ssDNA-QDs.
• This method overcomes limitations of existing conjugation techniques, enabling precise control and enhanced stability.
• The developed ssDNA-PC3-QDs facilitate emergent properties in DNA-based devices and photonic applications.