Dimeric Fluorescent Nucleic Acid Dyes for qPCR Sensitivity
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Solution Overview
Problem
Current fluorescent nucleic acid dyes used in quantitative real-time PCR (qPCR) face challenges such as low sensitivity, chemical instability, PCR inhibition, and limited compatibility with existing instrumentation, particularly with SYBR Green I, which has inhibitory effects and decomposes under alkaline conditions.
Innovation Solution
Development of dimeric or trimeric fluorescent nucleic acid dyes with a flexible neutral linker that form a hairpin structure, allowing for a 'release-on-demand' mechanism, reducing background fluorescence and PCR inhibition, and enhancing sensitivity by shifting equilibrium towards a nucleic acid-bound state, thereby increasing DNA detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SYBR Green I is used for DNA detection, then fluorescence signal is obtained, but PCR inhibition occurs and chemical stability deteriorates under alkaline conditions
Solution Approach 1:
The patent modifies the chemical structure of SYBR Green I by changing parameters such as the sulfur atom substitution (creating SYBR Green II) and linker chain length (creating analogs with 2-6 carbon chains). These parameter changes improve chemical stability under alkaline conditions while maintaining DNA binding affinity and fluorescence properties, resolving the contradiction between detection sensitivity and chemical stability.
Solution Approach 2:
The invention creates composite dye structures by combining modified cyanine dye cores with specific linker groups and terminal functionalities. The composite structure integrates stable chemical moieties (such as sulfonium groups and optimized linker chains) with DNA-binding functional groups, achieving both high stability and high sensitivity simultaneously.
2Measurement precision
If fluorescent dye concentration is increased to improve detection sensitivity, then signal strength increases, but PCR inhibition worsens
Solution Approach 1:
The patent optimizes the dye structure by modifying the linker chain length (2-6 carbons) and terminal group configurations, which changes the physical parameters of the dye molecule. These modifications reduce the dye's affinity for PCR components while maintaining DNA binding, allowing higher concentrations to be used without inhibition. For example, SYBR Green II and its analogs show reduced PCR inhibition compared to parent SYBR Green I at equivalent concentrations.
3Measurement precision
If existing fluorescent dyes are used, then DNA detection is achieved, but background fluorescence limits sensitivity
Solution Approach 1:
The patent modifies fluorescent dye structures by changing parameters such as the core cyanine structure, linker composition, and terminal groups to reduce intrinsic fluorescence while enhancing DNA-binding-induced fluorescence. The optimized dyes exhibit lower background fluorescence signals in the absence of DNA, improving the signal-to-noise ratio and detection sensitivity.
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 new dyes exhibit reduced background fluorescence, improved stability, and increased sensitivity, enabling higher concentrations to be used without inhibiting PCR, leading to enhanced DNA detection capabilities compared to existing dyes like SYBR Green I.
Implementation Method 1
Fluorescent dyes have been used for the detection and analysis of biological samples. As fluorescent dyes are highly sensitive, they can be used to detect a very small number of fluorescent molecules.
Implementation Method 2
Fluorescent nucleic acid dyes that specifically bind to nucleic acids and form highly fluorescent complexes are useful tools for such study.
Implementation Method 3
Several fluorescent probes having different fluorescent wavelengths may be used to perform multi-color imaging in live cells or tissue samples.
Implementation Method 4
Fluorescent probes are highly sensitive, of relatively low toxicity, and easy to dispose of relative to radioactive probes.
Implementation Method 5
Development of dimeric or trimeric fluorescent nucleic acid dyes with a flexible neutral linker that form a hairpin structure, allowing for a 'release-on-demand' mechanism, reducing background fluorescence and PCR inhibition
Data Source
AI summary
Dimeric and trimeric nucleic acid dyes, and associated systems and methods are provided. Such a dye may form a hairpin-like structure that enables it to stain nucleic acids via a release-on-demand mechanism, for example. Such a dye may have low background fluorescence in the absence of nucleic acids and high fluorescence in the presence of nucleic acids, upon binding therewith, for example. A dye provided herein may be useful in a variety of applications, such as in DNA quantitation in real-time PCR, for example.