Sugar-quantum dot conjugates for a selective and sensitive detection of lectins

Area of Science:

• Bioconjugation Chemistry
• Nanotechnology
• Carbohydrate Chemistry

Background:

• Quantum dots (QDs) offer unique optical properties but require stabilization in aqueous solutions.
• Neoglycoconjugates can be used to functionalize nanoparticles for specific biological interactions.
• Lectins are proteins that bind carbohydrates, playing roles in cell recognition and disease.

Purpose of the Study:

• To synthesize and characterize neoglycoconjugates for stabilizing and functionalizing cadmium selenide-zinc sulfide (CdSe-ZnS) quantum dots.
• To develop a novel agglutination assay for selective lectin detection using carbohydrate-functionalized QDs.
• To evaluate the sensitivity and selectivity of the developed assay for specific carbohydrate-lectin interactions.

Main Methods:

• One-pot synthesis of neoglycoconjugates with reactive thiol groups for QD functionalization.
• Characterization of synthesized sugar-QDs using transmission electron microscopy (TEM), fluorescence, and absorption spectroscopy.
• Development of a light scattering-based agglutination assay for lectin detection, monitoring scattered light at 600 nm.

Main Results:

• Successfully synthesized and characterized sugar-QDs with lactose, melibiose, and maltotriose.
• Demonstrated specific multivalent carbohydrate-lectin interactions leading to agglutination.
• Achieved selective binding, with soybean agglutinin (SBA) showing higher affinity for melibiose-QD than lactose-QD.
• Showcased specific deagglutination using alpha-d-galactose, while alpha-d-mannose had no effect.
• Detected as little as 100 nM of Concanavalin A (ConA) using maltotriose-QD, with enhanced sensitivity due to QD fluorescence.

Conclusions:

• The synthesized neoglycoconjugate-functionalized QDs are effective for stabilizing QDs in aqueous solution.
• The developed agglutination assay provides a highly selective and sensitive method for lectin detection.
• This platform enables specific identification of carbohydrate-lectin interactions and holds potential for diagnostic applications.