Light-Induced Oxidase Activity of DNAzyme-Modified Quantum Dots

Area of Science:

• Nanotechnology
• Bioconjugation Chemistry
• Biochemistry

Background:

• Quantum dots (QDs) offer unique optical properties for biosensing.
• DNAzymes are catalytic DNA molecules with diverse applications.
• Developing stable and efficient enzyme-mimicking systems is crucial for bioassays.

Purpose of the Study:

• To synthesize a covalent conjugate of quantum dots (QDs) and DNAzyme.
• To investigate the oxidase activity of the QD-DNA conjugate under visible light irradiation.
• To evaluate the potential of this system for developing novel cellular bioassays.

Main Methods:

• Amino-coupling conjugation of amino-modified oligonucleotides (CatG4-NH2) with carboxylated QDs (CdTe@COOH).
• Characterization using UV-Vis, fluorescence, circular dichroism (CD), IR spectroscopy, and transmission electron microscopy (TEM).
• Assessing catalytic activity using Amplex Red and ABTS indicators with light-induced reactive oxygen species (ROS) generation.

Main Results:

• Successfully synthesized a stable QD-DNA conjugate with low polydispersity in aqueous solutions.
• The QD-DNAzyme conjugate demonstrated enhanced catalytic activity compared to a mixture of QDs and DNAzyme.
• Light irradiation induced oxidase activity in the QD-DNAzyme system.

Conclusions:

• Covalent attachment of DNAzyme to QDs beneficially enhances catalytic activity.
• The QD-DNAzyme system enables light-induced signal generation.
• This system holds promise for developing advanced cellular bioassays, such as for determining oxygen radical scavengers.