Aptasensor Using G-Quadruplex DNAzyme for Sensitive Detection
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Solution Overview
Problem
Current biosensors for early disease diagnosis, such as breast cancer, face challenges in sensitivity and complexity due to reliance on expensive antibodies and enzymes, and time-consuming procedures, even when using aptamers and HRP-mimicking G-quadruplex DNAzymes, which require multiple incubations and washings.
Innovation Solution
An aptasensor comprising a first aptamer capable of binding with hemin, a second aptamer targeting a specific material, and a nucleotide linker, utilizing 1,1′-oxalyldiimidazole chemiluminescence to detect target materials like carcinoembryonic antigen (CEA) with enhanced sensitivity and reduced procedural complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional enzyme immunoassay with HRP-conjugated detection antibody is used, then sensitivity is improved, but cost and device complexity increase
Solution Approach 1:
The patent replaces expensive natural enzymes (HRP) with artificial enzyme-mimicking compounds (G-quadruplex DNAzymes) that copy the catalytic function of HRP. These DNAzymes can be synthesized chemically and perform similar chemiluminescence reactions, achieving comparable sensitivity without requiring animal-derived enzymes or complex conjugation procedures
Solution Approach 2:
The patent uses short-lived, easily synthesized DNA aptamers and DNAzymes that can be produced through SELEX and chemical synthesis rather than requiring expensive, stable protein-based antibodies and enzymes. These nucleic acid-based reagents are cost-effective and can be rapidly regenerated through synthesis
2Ease of manufacture
If aptasensor with fluorescent dye-conjugated detection aptamer is used, then cost is reduced, but detection sensitivity decreases
Solution Approach 1:
The patent changes the detection parameter from fluorescence to chemiluminescence. By using HRP-mimicking G-quadruplex DNAzymes that catalyze chemiluminescence reactions, the system achieves enhanced sensitivity comparable to enzyme immunoassay while maintaining the cost advantages of aptamer-based detection. The chemiluminescence signal provides higher signal-to-noise ratio than fluorescence
Solution Approach 2:
The patent creates a composite system combining DNA aptamers (for specific binding) with G-quadruplex DNAzymes (for catalytic chemiluminescence). This composite nucleic acid structure integrates both recognition and signal amplification functions, achieving high sensitivity without requiring external enzyme conjugation
3Measurement precision
If nanoparticles and microspheres are used to enhance aptasensor sensitivity, then detection sensitivity is improved, but procedural complexity and time consumption increase
Solution Approach 1:
The patent extracts and eliminates the time-consuming steps of nanoparticle modification, multiple incubations, and extensive washings from the detection procedure. By using free-standing G-quadruplex DNAzymes that directly catalyze chemiluminescence reactions upon target binding, the system achieves rapid detection without requiring complex nanoparticle-based signal amplification protocols
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The aptasensor achieves rapid and sensitive detection of target materials with reduced procedural complexity, offering a cost-effective and efficient method for early disease diagnosis by forming HRP-mimicking G-quadruplex DNAzyme and utilizing chemiluminescence for quantification, outperforming conventional methods in sensitivity and ease of use.
Implementation Method 1
adding a substrate for 1,1'-oxalyldiimidazole (ODI) chemiluminescence (CL); and measuring intensity of CL
Implementation Method 2
Hemin (FIG. 1(a)) is known as a HRP-mimicking compound. Also, the efficiency of hemin bound with DNA hemin aptamers, called HRP-mimicking G-quadruplex DNAzyme (FIG. 1(b)), is as good as that of HRP in enzyme immunoassay
Implementation Method 3
a second aptamer capable of binding with a target material
Data Source
AI summary
A method detects a target material in a sample, and includes: providing an aptasensor having a first aptamer capable of binding with hemin; a second aptamer capable of binding with the target material; and a nucleotide linker connecting the first aptamer and the second aptamer, adding hemin to the sample, contacting the aptasensor with the sample including hemin to bind the first aptamer with hemin and the second aptamer with the target material; adding a substrate for 1,1′-oxalyldiimidazole (ODI) chemiluminescence (CL), and measuring intensity of CL.