Thiolate-Capped CdSe/ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose

Area of Science:

• * Nanotechnology and Materials Science
• * Analytical Chemistry
• * Biochemistry

Background:

• * Development of sensitive and selective methods for glucose detection is crucial for clinical diagnostics.
• * Quantum dots (QDs) offer unique optical properties for biosensing applications.
• * Core-shell quantum dots provide enhanced stability and tunable fluorescence.

Purpose of the Study:

• * To synthesize and characterize semiconducting water-soluble core-shell quantum dots (CdSe/ZnS) for glucose detection.
• * To functionalize QDs with thiolated ligands for improved water solubility and stability.
• * To establish a fluorescence quenching-based assay for sensitive glucose determination using enzyme conjugation.

Main Methods:

• * Synthesis of CdSe/ZnS core-shell quantum dots via hot injection and SILAR techniques.
• * Ligand exchange with various thiolated compounds, including thio-glycolic acid (TGA), to achieve water solubility.
• * Characterization using transmission electron microscopy (TEM) and spectrofluorescence.
• * Glucose detection assay based on the fluorescence quenching of QDs upon reaction with glucose oxidase (GOx) and horseradish peroxidase (HRP).

Main Results:

• * Synthesized CdSe/ZnS QDs with a particle size of 10-12 nm and optimal emission at 620 nm.
• * CdSe/ZnS QDs capped with TGA (CdSe/ZnS-TGA) exhibited the strongest fluorescence.
• * The developed GOx:HRP/CdSe/ZnS-TGA QDs system demonstrated a fluorescence quenching effect correlated with glucose concentration.
• * Successful application for fluorescence-based glucose determination in aqueous samples.

Conclusions:

• * The synthesized CdSe/ZnS-TGA core-shell quantum dots are effective for sensitive glucose detection.
• * The enzyme-conjugated QD system provides a robust platform for fluorescence-based glucose assays.
• * This approach holds potential for the development of novel diagnostic tools for glucose monitoring.