Digital Nuclease Detection With Picodroplet Bead-Bound Probes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting and quantifying nuclease concentrations are non-linear and require standard curves, leading to inaccuracies and difficulties in precise quantification, especially for single nuclease molecules.
Innovation Solution
A detection method using picodroplets with quenched fluorescent oligonucleotide probes immobilized on magnetic beads, where nuclease digestion separates fluorophore and quencher, allowing for digital detection of nuclease molecules without a standard curve, utilizing a Poisson distribution for quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional nuclease detection methods are used, then quantification can be performed, but standard curves are required and measurement precision deteriorates
Solution Approach 1:
The invention divides the detection system into discrete digital units (presence/absence of signal in individual droplets) rather than continuous analog measurement. By segmenting the sample into multiple droplets and scoring each as positive or negative, the method achieves precise quantification without requiring standard curves, directly resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The assay system performs self-quantification through digital counting of positive droplets. The method uses the sample itself as the reference, eliminating the need for external standard curves. The Poisson distribution mathematics provides the self-service quantification function, allowing accurate nuclease concentration determination directly from the digital data without additional calibration materials.
2Measurement precision
If linear detection methods are used, then quantification is possible, but single-molecule sensitivity is insufficient
Solution Approach 1:
By segmenting the reaction into thousands of individual droplets, the invention enables single-molecule sensitivity through statistical accumulation. Each droplet acts as an independent detection unit, and the collective digital count provides both high sensitivity and rapid quantification, resolving the contradiction between single-molecule detection capability and quantification speed.
Solution Approach 2:
The invention replaces conventional linear signal accumulation with digital counting mechanics. Instead of measuring continuous signal intensity that requires sensitive amplification, the method uses binary presence/absence detection in discrete droplets, achieving single-molecule sensitivity through statistical methods rather than signal amplification mechanics.
3Ease of manufacture
If FRET-based quenching is used, then fluorescent quenching occurs, but spectral overlap requirements complicate probe design
Solution Approach 1:
The invention changes the quenching mechanism from FRET-based (requiring spectral overlap) to collisional/ground-state quenching. By using quenchers that operate through non-FRET mechanisms, the method eliminates spectral overlap requirements, greatly simplifying probe design and expanding the range of compatible fluorophore-quencher pairs while maintaining ease of manufacture.
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
Enables precise quantification of nuclease molecules with single-molecule sensitivity and a binary output, eliminating the need for standard curves and providing a simple, sensitive method for nuclease detection.
Implementation Method 1
Chemical moieties that quench fluorescent light operate through a variety of mechanisms, including fluorescence resonance energy transfer (FRET) processes and ground state quenching. FRET is one of the most common mechanisms of fluorescent quenching and can occur when the emission spectrum of the fluorescent donor overlaps the absorbance spectrum of the quencher and when the donor and quencher are within a sufficient distance known as the Forster distance.
Implementation Method 2
Ground-state quenching can occur in the absence of spectral overlap if the fluorophore and quencher are sufficiently close together to form a ground state complex.
Implementation Method 3
Endonucleases (e.g., certain ribonucleases and deoxyribonucleases) are enzymes that cleave the phosphodiester bond within a polynucleotide (DNA or RNA) chain
Implementation Method 4
substrate probe operably linked to a magnetic microbead
Data Source
AI summary
In certain embodiments, the present invention provides a detection composition comprising a picodroplet comprising (a) an aqueous solution, and (b) a substrate probe comprising (i) an oligonucleotide of 2 to 75 nucleotides in length, (ii) a fluorophore operably linked to the oligonucleotide, and (iii) a quencher operably linked to the oligonucleotide. As used herein, the term “picodroplet” comprises a liquid droplet that has a volume of 0.014 to 2.6 picoliters. In certain embodiments, the present invention provides a method of detecting at least one individual nuclease molecule present in a sample, comprising contacting an aqueous sample suspected of containing at least one nuclease with at least one detection composition comprising a picodroplet comprising (a) an aqueous solution, and (b) a substrate probe comprising (i) an oligonucleotide of 2 to 75 nucleotides in length, (ii) a fluorophore operably linked to the oligonucleotide, and (iii) a quencher operably linked to the oligonucleotide to form an aqueous reaction mixture; emulsifying the aqueous mixture in oil to form picoliter-scale droplets in an emulsion, (c) incubating the picoliter-scale droplets in the emulsion in order for the nuclease, if present, to digest the substrate probes linked to the microbeads; recovering the microbeads; and detecting fluorescence emitting from the microbeads.