Fluorescence detection of Pb(2+) based on the DNA sequence functionalized CdS quantum dots

Area of Science:

• Nanotechnology
• Biochemistry
• Environmental Science

Background:

• Quantum dots (QDs) offer unique optical properties for biosensing.
• Lead (Pb2+) is a toxic heavy metal requiring sensitive detection methods.
• DNA-based sensors leverage specific molecular interactions for analyte recognition.

Purpose of the Study:

• To develop a simple, rapid, and label-free fluorescent sensor for Pb2+ detection.
• To utilize DNA-capped cadmium sulfide quantum dots (CdS QDs) for enhanced sensing capabilities.
• To investigate the mechanism of Pb2+ detection based on fluorescence recovery.

Main Methods:

• Synthesis of guanine (G)-rich DNA sequence (PS2.M) capped CdS QDs.
• Formation of G-quadruplex/hemin complex with K+ leading to fluorescence quenching of CdS QDs via photoinduced electron transfer.
• Detection of Pb2+ by observing the recovery of quenched fluorescence.

Main Results:

• The synthesized DNA-capped CdS QDs exhibited fluorescence quenching in the presence of the G-quadruplex/hemin complex.
• Pb2+ induced conformational changes in the complex, releasing hemin and recovering CdS QD fluorescence.
• The fluorescence recovery demonstrated a clear correlation with Pb2+ concentration, indicating successful detection.

Conclusions:

• A novel fluorescent sensing platform for Pb2+ detection was successfully developed using DNA-capped CdS QDs.
• The method is simple, rapid, and label-free, offering a promising approach for environmental monitoring.
• The G-quadruplex/hemin complex plays a crucial role in the fluorescence quenching and recovery mechanism for Pb2+ detection.