Universal Quantum Dot Probes for Closed-Tube LAMP Detection
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Solution Overview
Problem
Existing isothermal nucleic acid amplification techniques face challenges with organic fluorophores' poor photostability and the need for target-specific oligonucleotide-modified quantum dots, leading to susceptibility to carryover contamination and high costs.
Innovation Solution
A universal fluorescent probing system using surface-modified semiconductor quantum dots (CdSeS/ZnS) that form coprecipitates with magnesium pyrophosphate crystals during isothermal amplification, enabling closed-tube detection without target-specific oligonucleotide attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If organic fluorophores are used for real-time monitoring of amplification reactions, then detection capability is improved, but photostability deteriorates leading to poor storage and handling
Solution Approach 1:
The patent replaces photostable but expensive target-specific oligonucleotide-modified QDs with simple, unmodified QDs that are inexpensive and can be used in a disposable closed-tube format. The QDs themselves are not consumed but the closed-tube reaction mixture is discarded after use, eliminating carryover contamination risks while maintaining detection capability through coprecipitation with Mg2P2O7 crystals.
Solution Approach 2:
The patent introduces Mg2P2O7 crystals as an intermediary that mediates between the QDs and the target nucleic acid amplification products. The crystals coprecipitate with the QDs in a target-dependent manner, providing a visual signal without requiring direct interaction between the QDs and the target sequence, thus enabling universal detection.
2Object-affected harmful factors
If target-specific oligonucleotide-modified quantum dots are used for closed-tube detection, then contamination resistance is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes QDs universal by removing target-specific oligonucleotide modifications. The same unmodified QDs can be used with any LAMP or RT-LAMP reaction by relying on the coprecipitation mechanism with Mg2P2O7 crystals, which are produced in all successful amplification reactions regardless of the specific target sequence.
Solution Approach 2:
The patent eliminates the need for expensive oligonucleotide-modified QDs by using simple, unmodified QDs in a disposable closed-tube format. The closed-tube reaction mixture is discarded after use, preventing carryover contamination, while the QDs themselves remain inexpensive and can be reused if needed.
3Measurement precision
If postamplification open-tube addition of QD detection probes is used, then detection sensitivity is improved, but contamination susceptibility worsens
Solution Approach 1:
The patent merges the detection function with the amplification reaction by adding QDs to the closed tube before amplification. The QDs coprecipitate with Mg2P2O7 crystals produced during the reaction, providing real-time detection without requiring separate detection steps or opening the tube, thus preventing contamination while maintaining sensitivity.
Solution Approach 2:
The patent uses Mg2P2O7 crystals as an intermediary that forms during the amplification reaction and coprecipitates with QDs. This intermediary enables detection sensitivity by providing a visible signal while keeping the system closed throughout the process, eliminating contamination risks associated with open-tube postamplification addition.
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 provides stable, cost-effective, and contamination-free real-time monitoring of nucleic acid amplification reactions, with sensitivity to low copy numbers of target sequences and compatibility with LAMP and RT-LAMP reactions.
Implementation Method 1
a plurality of functionalized fluorescent nanoprobes capable of forming coprecipitates in the presence of positive isothermal amplification reaction products along with a target sequence amplification
Implementation Method 2
Fluorescent semiconductor nanocrystals (quantum dots; QDs) have been proved to be promising substitutes for organic fluorophores by virtue of their superior photostability and brightness
Data Source
AI summary
The present invention provides a universal fluorescent probing system and method for result readout of loop-mediated isothermal amplification (LAMP) or reverse transcription-loop-mediated isothermal amplification (RT-LAMP) in a closed-tube manner using at least three different types of universal quantum dot probes, including sulfonate-, carboxyl-, and amine-modified quantum dots (QDs). Detection mechanism of the present system and method relies on a co-precipitation of the modified QDs with magnesium pyrophosphate crystals (one of the positive LAMP/RT-LAMP reaction products) formed during the reaction. The present system and method are advantageous over the existing technologies in terms of simple preparation, low cost, as well as excellent universality, specificity and sensitivity.