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Updated: May 31, 2026
14:53
A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis
Published on: September 10, 2014
Sequence-Engineered G-Triplex/Methylene Blue System as a Label-Free Electrochemical Signal Module for Biosensor
Ling-Li Zhao1, Jia-Le Li2, Ruo-Yao Cui3
1Department of Chemistry, Zhejiang University, Hangzhou 310027, China.
Analytical Chemistry
|May 28, 2026
Summary
Researchers optimized guanine triplex (G-triplex) DNA sequences for enhanced interaction with methylene blue (MB). The best G-triplex sequence was used in an electrochemical biosensor for sensitive melamine detection.
Area of Science:
- Biochemistry
- Nanotechnology
- Analytical Chemistry
Background:
- G-triplexes are noncanonical DNA structures with unclear sequence design rules for small-molecule binding.
- Optimizing G-triplex sequences is crucial for developing novel biosensing applications.
- Methylene blue (MB) is a redox indicator often used in electrochemical assays.
Purpose of the Study:
- To systematically screen and optimize G-triplex DNA sequences for improved binding with methylene blue (MB).
- To develop an electrochemical biosensor utilizing the optimized G-triplex sequence for sensitive melamine detection.
- To provide a framework for G-triplex sequence design in molecular recognition and sensing.
Main Methods:
- Systematic sequence screening of over 80 candidate G-triplex sequences with variations in loop nucleotides, flanking bases, and strand length.
- Evaluation of sequences using square wave voltammetry and circular dichroism spectroscopy.
- Construction of a hairpin probe (MelaPin) integrating the optimal G-triplex sequence with a melamine recognition region for biosensor development.
Main Results:
- The optimal G-triplex sequence (F9) demonstrated significantly higher current suppression upon MB binding compared to other G-triplex and G-quadruplex sequences.
- F9 formed a stable parallel G-triplex with a melting temperature of 65.1 °C, increasing to 70.0 °C with MB binding.
- The developed electrochemical biosensor exhibited a linear response to melamine from 1-100 μM with a low detection limit (0.74 μM) and high recovery in infant formula.
Conclusions:
- A practical framework for designing G-triplex sequences with enhanced small-molecule binding properties was established.
- The optimized G-triplex/MB system serves as an effective, label-free signal module for electrochemical biosensing.
- This approach offers a promising strategy for developing sensitive and reliable biosensors for various analytes.
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