CRISPR-Cas13a Diagnostic System for Malaria Detection
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Solution Overview
Problem
Current nucleic acid detection methods face challenges in achieving high sensitivity and specificity while being cost-effective and suitable for point-of-care settings, often requiring complex instrumentation or sacrificing sensitivity for portability.
Innovation Solution
A CRISPR-based system comprising an effector protein, guide RNAs, and an RNA-based masking construct, optionally with nucleic acid amplification reagents, designed to detect target molecules with high specificity and sensitivity, capable of amplifying RNA or DNA targets and generating detectable signals for diagnostic purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If qPCR approaches are used for nucleic acid detection, then sensitivity is improved, but device complexity and cost increase due to expensive instrumentation and complex操作流程
Solution Approach 1:
The patent replaces complex mechanical/optical detection systems (qPCR instrumentation) with a biochemical detection system based on CRISPR-Cas13a collateral cleavage activity. The system uses a simple fluorescence readout from a masked construct that is cleaved by activated Cas13a, eliminating the need for expensive thermal cyclers and complex optical detection systems while maintaining high detection sensitivity
Solution Approach 2:
The patent introduces an intermediary RNA-based masked construct that translates the specific CRISPR-Cas13a target recognition event into a measurable fluorescence signal. This masked construct acts as a mediator between the specific molecular recognition (guide RNA-target RNA binding) and the simple fluorescence readout, enabling complex detection capability with simple instrumentation
2Device complexity
If isothermal nucleic acid amplification with portable platforms is used, then device complexity is reduced for point-of-care use, but detection sensitivity decreases
Solution Approach 1:
The patent merges isothermal amplification (RPA) with CRISPR-Cas13a detection in a single integrated assay system. The RPA amplification step generates sufficient target RNA from minimal input, and the Cas13a collateral cleavage provides signal amplification, achieving high sensitivity (detecting as few as 10 copies of target RNA) in a portable format without requiring thermal cyclers
Solution Approach 2:
The patent changes the detection parameter from direct target quantification to collateral cleavage activity measurement. By measuring the non-specific RNAse activity of activated Cas13a on a masked construct rather than directly detecting the target, the system achieves signal amplification that maintains high sensitivity while enabling simple fluorescence-based readout suitable for point-of-care devices
3Ease of manufacture
If conventional nucleic acid detection methods are used, then cost is reduced, but detection specificity for single-base differences deteriorates
Solution Approach 1:
The patent uses preliminary isothermal amplification (RPA) to enrich target sequences before detection, ensuring that even single-copy targets are amplified to detectable levels. This preliminary amplification step, combined with the high specificity of CRISPR-Cas13a recognition, enables detection of single-base differences at low cost without requiring expensive sequencing or complex hybridization assays
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 system enables attomolar sensitivity in detecting nucleic acids and differentiating targets from non-targets based on single base pair differences, suitable for various healthcare applications, including viral detection and disease-associated cell-free DNA, with potential for point-of-care use.
Implementation Method 1
a CRISPR system comprising an effector protein and one or more guide RNAs designed to bind to corresponding target molecules
Implementation Method 2
Activating the CRISPR effector protein via binding of the one or more guide RNAs to one or more target molecules, wherein activating the CRISPR effector protein results in modification of the RNA-based masking construct such that a detectable positive signal is produced
Implementation Method 3
nucleic acid amplification reagents to amplify target RNA molecules in a sample
Implementation Method 4
The nucleic acid may be RNA and amplified by a reverse transcription method as described herein
Data Source
AI summary
The embodiments disclosed herein utilized RNA targeting effectors to provide a robust CRISPR-based diagnostic with attomolar sensitivity. Embodiments disclosed herein can detect broth DNA and RNA with comparable levels of sensitivity and can differentiate targets from non-targets based on single base pair differences. Moreover, the embodiments disclosed herein can be prepared in freeze-dried format for convenient distribution and point-of-care (POC) applications. Such embodiments are useful in multiple scenarios in human health including, for example, viral detection, bacterial strain typing, sensitive genotyping, and detection of disease-associated cell free DNA.