A highly sensitive and selective optical sensor for Pb2+ by using conjugated polymers and label-free oligonucleotides

Area of Science:

• Analytical Chemistry
• Biotechnology
• Environmental Science

Background:

• Lead (Pb2+) detection is crucial but often hindered by mercury (Hg2+) interference in DNA biosensors.
• Existing methods for mercury masking are often complex or use toxic agents.

Purpose of the Study:

• To develop a rapid, sensitive, and selective label-free sensor for Pb2+ detection.
• To overcome the interference of Hg2+ in Pb2+ determination using a novel biosensing strategy.

Main Methods:

• Utilized a specific DNA sequence (TBAA) that forms G-quadruplex structures upon Pb2+ binding.
• Employed a cationic water-soluble conjugated polymer (PMNT) as a "polymeric stain" for optical signal transduction.
• Developed a simple "mix-and-detect" optical sensor based on distinguishable optical properties of PMNT-DNA complexes.

Main Results:

• Achieved naked-eye detection of micromolar Pb2+ concentrations within 5 minutes.
• Improved the detection limit to the nanomolar range using fluorometric analysis.
• Successfully applied the biosensor for Pb2+ determination in real tap water samples.

Conclusions:

• The developed G-quadruplex-based biosensor offers a promising alternative for Pb2+ determination in the presence of Hg2+.
• This label-free, rapid, and sensitive method simplifies Pb2+ analysis without requiring masking agents.
• The biosensor demonstrates practical applicability for environmental monitoring of lead contamination.