cfDNA Reference Material Generation via Chromatin Crosslinking
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Solution Overview
Problem
There is a need for synthetic cell-free DNA (cfDNA) reference materials that can be reproducibly made and have known properties to verify the accuracy of diagnostic tests detecting and monitoring cfDNA in biological samples, as existing methods lack standardization and reliability.
Innovation Solution
A method involving the generation of cfDNA reference material by providing chromatin with DNA wrapped around histones, treating it with formaldehyde to form crosslinks, and then using acoustic energy and enzymes to shear and digest the chromatin into fragments that mimic native cfDNA, ensuring predictable interaction with diagnostic tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If synthetic cfDNA reference material is created without standardized methods, then manufacturing flexibility is maintained, but manufacturing precision and reliability deteriorate
Solution Approach 1:
The chromatin preparation process is divided into discrete, standardized steps: chromatin extraction from defined cell sources, controlled crosslinking with formaldehyde at specific concentrations and times, standardized acoustic shearing parameters to achieve consistent fragment sizes (100-500 bp), and controlled enzymatic digestion. Each step uses defined parameters that can be reproduced across different manufacturing batches.
Solution Approach 2:
The invention establishes specific parameter ranges for cfDNA reference material production: formaldehyde concentration (0.1-1% v/v), crosslinking time (5-30 minutes), acoustic shearing energy levels and duration, and enzymatic digestion conditions. These parameter specifications transform the manufacturing process from flexible but inconsistent to standardized with controlled variability, achieving manufacturing precision while maintaining reasonable process complexity.
2Measurement precision
If cfDNA reference material is produced with unknown properties, then production simplicity is maintained, but measurement precision and diagnostic verification reliability deteriorate
Solution Approach 1:
The manufacturing process incorporates quality control feedback loops where cfDNA fragment size distribution is measured using gel electrophoresis or sequencing after each major step (chromatin extraction, shearing, digestion). Concentration is monitored using fluorometric assays. This feedback allows real-time adjustment of process parameters to ensure consistent, known properties in the final product, achieving measurement precision without significantly complicating manufacturing through automated control systems.
Solution Approach 2:
The invention creates cfDNA reference material that copies the essential properties of native cfDNA (fragment size distribution, sequence content from known cell lines, chemical modifications) through standardized production methods. By using well-characterized cell lines as templates and replicating their cfDNA properties in controlled conditions, the reference material achieves known, measurable properties while maintaining ease of manufacture through repeated copying of the same proven protocol.
3Reliability
If diagnostic tests are verified without standardized reference materials, then test development speed is maintained, but reliability of diagnostic accuracy verification deteriorates
Solution Approach 1:
The invention provides cfDNA reference material with pre-defined, characterized properties (known fragment size distributions, sequences from authenticated cell lines, controlled concentration ranges) before diagnostic tests are developed or verified. This preliminary characterization allows multiple diagnostic tests to be verified against the same standardized reference, improving reliability of accuracy verification while maintaining productivity through efficient reuse of the reference material across different test validations.
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 method produces cfDNA reference material with controlled fragment sizes and properties, enhancing the accuracy and reliability of diagnostic tests by mimicking natural cfDNA, thus addressing the need for standardized verification of diagnostic tools and protocols.
Implementation Method 1
the chromatin may be treated with formaldehyde to generate crosslinks between DNA and histones
Implementation Method 2
the sheared chromatin may be treated with an enzyme to digest DNA in linker regions of the chromatin between nucleosomes
Data Source
AI summary
cfDNA reference material, for example, for use in verifying the accuracy and effectiveness of a diagnostic test, is generated from chromatin which may be sourced from whole cells. The chromatin may be treated with formaldehyde to form crosslinks between DNA and histones, for example, while the chromatin is contained within nuclear and/or plasma membranes. The fixed chromatin may be sheared by acoustic energy, which may also be used to lyse cell membranes within which the fixed chromatin may be contained. The sheared chromatin may be treated with an enzyme, such as micrococcal nuclease, to digest chromatin in linker regions of the DNA between nucleosomes and generate nucleosome material for use as cfDNA reference material.