Two-Stage Nucleic Acid Amplification via Hybridization Chain Reaction
Solution Overview
Problem
Current nucleic acid amplification techniques, such as PCR, face limitations in distinguishing between multiple nucleic acids from the same sample and are inconsistent due to sample purity and complexity, particularly in quantitating RNA, where enzyme-dependent methods like QPCR struggle with base modifications and secondary structures.
Innovation Solution
A two-stage amplification method using amplification oligomers that are non-enzymatically amplified and then used as substrates for a second amplification assay, allowing for the detection and quantitation of multiple nucleic acids from the same sample by hybridizing unique sequences to capture and label probes, enhancing sensitivity and specificity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If enzyme-dependent amplification techniques (QPCR) are used to quantitate nucleic acids, then amplification sensitivity is improved, but consistency and reliability deteriorate due to sample purity and complexity issues
Solution Approach 1:
The patent replaces enzyme-dependent amplification (QPCR) with a non-enzymatic isothermal amplification system using hybridization chain reaction (HCR). This substitution eliminates the need for polymerase enzymes, thereby avoiding the inconsistency issues caused by enzyme activity variations in complex or degraded samples while maintaining high amplification sensitivity through cooperative hybridization mechanisms.
Solution Approach 2:
The patent changes the fundamental parameter of amplification mechanism from enzymatic to non-enzymatic, and from thermal cycling to isothermal conditions. This parameter change allows the system to operate reliably in complex samples without requiring high nucleic acid purity or sophisticated temperature control, thereby improving both sensitivity and consistency simultaneously.
2Productivity
If QPCR is used for RNA quantification, then amplification capability is improved, but measurement precision deteriorates due to reverse transcription inefficiencies and base modifications
Solution Approach 1:
The patent eliminates the reverse transcription step by using DNA-based HCR amplification that can directly hybridize to RNA targets or to DNA copies generated without reverse transcription. This substitution removes the source of quantitation errors related to reverse transcription efficiency and base modification sensitivity, thereby improving measurement precision while maintaining amplification capability.
Solution Approach 2:
The patent introduces DNA-based intermediary probes and amplification oligomers that mediate between the RNA target and the detection system. These intermediaries avoid direct enzyme-mediated conversion of RNA to cDNA, thereby preserving quantitation accuracy by eliminating reverse transcription-related losses and artifacts while still enabling amplification.
3Adaptability or versatility
If multiple pooled gene-specific primers are used in QPCR to detect multiple nucleic acids, then detection versatility is improved, but device complexity and measurement precision deteriorate
Solution Approach 1:
The patent segments the detection system into multiple distinct HCR probe sets, each with unique barcode sequences that can be individually tracked. This segmentation allows simultaneous detection of multiple nucleic acid targets without requiring pooled primers, thereby maintaining multiplex versatility while reducing the complexity associated with primer design and optimization.
Solution Approach 2:
The patent uses barcode sequences that are copied and amplified along with the target nucleic acids through the HCR process. This copying mechanism enables the detection system to simultaneously track multiple targets through their unique barcodes, achieving multiplex versatility without the complexity of managing multiple pooled primers, as each target is independently amplified and detected.
4Measurement precision
If QPCR amplification cycles are increased to detect rare nucleic acids, then detection sensitivity is improved, but measurement precision deteriorates due to error accumulation
Solution Approach 1:
The patent replaces thermal cycling-based PCR amplification with isothermal HCR amplification. This substitution eliminates the repeated denaturation, annealing, and extension cycles that accumulate errors in QPCR. The isothermal HCR process maintains higher fidelity by using cooperative hybridization without thermal stress, thereby improving detection sensitivity for rare nucleic acids while maintaining reliability through reduced error accumulation.
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
This method significantly increases the sensitivity of nucleic acid assays, enabling the identification and quantitation of rare nucleic acids in complex mixtures and allowing for simultaneous analysis of multiple nucleic acids, improving upon the limitations of existing techniques by reducing non-specific binding and enhancing signal amplification.
Implementation Method 1
hybridizing a first amplification multimer to the first nucleic acid of interest; hybridizing the amplification multimer to one or more first amplification oligomers
Data Source
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AI summary
This invention provides methods, compositions and systems to detect a nucleic acid of interest in a two-stage amplification. The two-stage amplification begins with a first non-enzymatic accumulation of an amplification oligomer that is the target substrate for a second nucleic acid amplification or assay. Two or more amplification oligomers can be used to allow multiplexed amplifications of two or more nucleic acids of interest with deconvolution based on unique detection signals or unique signal locations.