Label-free Pb²⁺ detection on the layer-by-layer platform using real-time dual polarization interferometry.

Area of Science:

• Environmental Science
• Biotechnology
• Analytical Chemistry

Background:

• Lead ion (Pb²⁺) contamination is a significant environmental and health concern.
• Sensitive and reliable detection methods for Pb²⁺ are crucial for water pollution management.
• Existing biosensors often require complex nanomaterials or labeling.

Purpose of the Study:

• To develop a simple, sensitive, and label-free biosensor for Pb²⁺ detection.
• To utilize the conformational changes of guanine-rich (G-rich) oligonucleotides upon Pb²⁺ binding for sensing.
• To establish a robust sensing platform using layer-by-layer assembly.

Main Methods:

• Direct conformational changes of G-rich oligonucleotides upon Pb²⁺ binding were monitored using dual polarization interferometry (DPI).
• A sensing platform was constructed via layer-by-layer assembly using polyethyleneimine and polythymine as media layers.
• G-rich DNA was immobilized on the DPI chip without sophisticated nanomaterial synthesis.

Main Results:

• The binding of Pb²⁺ induced a conformational transition from single-stranded DNA to G-quadruplex structures.
• Real-time monitoring of these conformational changes by DPI enabled quantitative detection of Pb²⁺.
• A label-free biosensor with high sensitivity and specificity for Pb²⁺ was successfully established.

Conclusions:

• The developed DPI-based biosensor offers a simple and sensitive method for detecting lead ions.
• This approach demonstrates the potential of combining surface techniques with biosensing applications.
• The study highlights the relationship between DNA structure and function in biosensor development.