Digital Warm-Start CRISPR Assay for SARS-CoV-2 Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for detecting SARS-CoV-2, such as TaqMan probe-based RT-PCR and isothermal nucleic acid amplification techniques, face challenges in sensitivity, specificity, and cost-effectiveness, particularly in small clinics or community health settings, with isothermal methods often experiencing nonspecific amplification issues.
Innovation Solution
A digital warm-start CRISPR (WS-CRISPR) assay using a one-pot reaction mixture containing Cas12a-crRNA complex, DAMP primers, reverse transcriptase, and pyrophosphatase, partitioned into sub-nanoliter microreactions, which enables sensitive and specific detection of SARS-CoV-2 RNA without premature amplification, utilizing phosphorothioated primers and pyrophosphatase to stabilize magnesium ions for efficient CRISPR-Cas12a activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TaqMan probe-based RT-PCR is used for SARS-CoV-2 detection, then sensitivity and specificity are improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the complex mechanical real-time PCR instrument system with a simplified isothermal CRISPR-Cas12a detection system. The CRISPR-Cas12a assay uses a one-pot reaction that can be performed without expensive thermal cyclers, substituting the mechanical complexity of RT-PCR instrumentation with a biochemically simpler isothermal amplification approach that achieves comparable sensitivity and specificity.
Solution Approach 2:
The patent changes the reaction temperature parameter from variable temperature cycling (RT-PCR) to constant isothermal conditions (50-55°C for CRISPR-Cas12a). This parameter change eliminates the need for complex thermal cycling instruments while maintaining detection sensitivity, and the isothermal condition simplifies the device requirements for point-of-care settings.
2Device complexity
If isothermal nucleic acid amplification methods are used for SARS-CoV-2 detection, then device complexity is reduced, but measurement precision deteriorates due to nonspecific amplification
Solution Approach 1:
The patent introduces CRISPR-Cas12a as an intermediary detection layer that follows isothermal amplification. The Cas12a enzyme specifically recognizes and cleaves target sequences with high precision, acting as a mediator that eliminates nonspecific amplification signals. This two-step approach (amplification followed by specific CRISPR recognition) maintains measurement precision while keeping the overall system simple and isothermal.
Solution Approach 2:
The patent performs preliminary isothermal amplification to generate sufficient target copies, then follows with CRISPR-Cas12a specific recognition to ensure accurate detection. This preliminary amplification step ensures that even low-abundance targets are amplified to detectable levels before the specific CRISPR recognition step, improving quantitation accuracy without requiring complex instruments.
3Measurement precision
If digital partitioning is applied to CRISPR assay, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the reaction mixture into numerous sub-nanoliter microreactions using digital microfluidics or partitioning into microwells. Each microreaction independently processes a small aliquot of the sample, and the collective results provide statistically robust quantitation. This segmentation improves measurement precision by reducing well-to-well variability and enabling absolute quantification without standard curves, while the modular nature of digital partitioning allows for scalable implementation.
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 digital WS-CRISPR assay achieves high sensitivity and specificity, capable of detecting down to 50 copies/μl SARS-CoV-2 RNA, with improved detection accuracy and reduced nonspecific signals, facilitating quantitative detection and direct saliva testing without RNA extraction, making it suitable for various healthcare settings.
Implementation Method 1
The CRISPR-Cas12a complex specifically binds the target sequence and induces selective cleavage, which generates a fluorescent signal that can be detected and/or measured to determine the presence and/or amount of target within the sample
Implementation Method 2
utilizing phosphorothioated primers and pyrophosphatase to stabilize magnesium ions for efficient CRISPR-Cas12a activity
Implementation Method 3
A digital warm-start CRISPR (WS-CRISPR) assay using a one-pot reaction mixture containing Cas12a-crRNA complex, DAMP primers, reverse transcriptase, and pyrophosphatase
Data Source
AI summary
The disclosure provides materials and methods for detection of pathogens. In particular, the disclosure provides primers and compositions for detection of viral pathogens, such as SARS-CoV-2. In addition, the disclosure provides a warm-start digital CRISPR assay for detection of viral pathogens, including SARS-CoV-2.