Catalysts for Reversing Formaldehyde Cross-Links in Biological Samples
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Solution Overview
Problem
Formaldehyde treatment of biological samples leads to chemical cross-linking, making nucleic acids and proteins inaccessible for detection and analysis, particularly hindering methods like PCR, as existing solutions only degrade proteins or use detergents without altering covalent bonds.
Innovation Solution
Contacting formaldehyde cross-linked biological samples with specific catalysts, such as aminophenylboronic acids, cyclic boronic acid esters, and bismuth salts, to release cross-linked components, thereby improving their accessibility for analysis, and optionally using proteases to further degrade proteins and enhance nucleic acid availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If formaldehyde treatment is applied to preserve biological samples, then tissue preservation and cellular feature preservation are improved, but nucleic acid and protein accessibility for detection is worsened
Solution Approach 1:
The patent uses formaldehyde as an intermediary substance that initially serves to preserve tissue by cross-linking proteins and nucleic acids. Later, specific reagents (such as hydroxylamine or boronic acid derivatives) are introduced as intermediary agents to reverse the cross-linking by forming alternative bonds with the formaldehyde-modified groups, thereby releasing the nucleic acids while preserving the tissue structure for detection
Solution Approach 2:
The patent changes the chemical parameters of the system by introducing reagents with specific chemical properties (nucleophilic character, pH conditions) that alter the stability of formaldehyde cross-links. By adjusting parameters such as pH, temperature, and reagent concentration, the cross-linking is reversed under controlled conditions, making nucleic acids accessible for detection while maintaining tissue integrity
2Stability of the object's composition
If formaldehyde cross-linking is used to fix tissue, then cellular structure preservation is improved, but PCR amplification effectiveness is worsened
Solution Approach 1:
The patent introduces specific chemical reagents (hydroxylamine, boronic acid derivatives) as intermediary substances that selectively react with formaldehyde cross-linked nucleic acids. These intermediaries form reversible or cleavable bonds with the cross-linked nucleic acids, releasing them from protein associations while leaving the overall cellular structure intact, thereby enabling subsequent PCR amplification
Solution Approach 2:
The patent modifies reaction parameters including pH (typically alkaline conditions for hydroxylamine), temperature (elevated temperatures to facilitate cross-link reversal), and reagent concentration to optimize the balance between maintaining cellular structure stability and enabling nucleic acid release for PCR amplification
3Difficulty of detecting and measuring
If protein degradation is used to improve nucleic acid accessibility, then nucleic acid availability is improved, but sample integrity and protein detection capability are worsened
Solution Approach 1:
The patent uses chemical reagents (hydroxylamine, boronic acid derivatives) as intermediaries that specifically target and reverse formaldehyde cross-links involving nucleic acids. These intermediaries selectively release nucleic acids without requiring broad-spectrum protein degradation, thereby maintaining sample integrity and preserving proteins for parallel detection and analysis
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
This approach increases the accessibility of biological components by 2- to 10-fold, allowing for effective detection and quantification of nucleic acids and proteins, even in samples embedded in paraffin, by reversing the cross-linking process without damaging the molecules.
Implementation Method 1
contacting the sample with a sufficient amount of a catalyst to release at least a portion of the cross-linked component
Implementation Method 2
contacting the sample with a protease to degrade the protein in the sample
Data Source
AI summary
Catalysts act to release formaldehyde cross-linking that occurs in biological samples. Thus, contacting catalysts to formaldehyde fixed samples is a useful way to render biological components of the samples, including nucleic acids or proteins, more accessible to detection and characterization.