Ionic Liquid NIR Dye Composition for DNA-Safe Bloodstain Detection
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Solution Overview
Problem
Current presumptive bloodstain tests, such as luminol, are unreliable in the presence of cleaning agents, require dark conditions, and can damage DNA, making it difficult to accurately detect and analyze bloodstains in forensic investigations.
Innovation Solution
A composition comprising an ionic liquid and a near-infrared (NIR) dye, specifically choline glycolate with a 1:1 ratio and SO3SQ, which selectively binds to human serum albumin in blood, enhancing fluorescence in the NIR range and providing a stable, long-lasting detection method that does not damage DNA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If luminol test is used for bloodstain detection, then blood can be detected through chemiluminescence, but the test requires dark conditions and the luminescence is short-lived
Solution Approach 1:
The patent employs a fluorescent dye that changes its emission properties upon binding to blood components. Instead of relying on chemiluminescence that requires dark conditions, the invention uses fluorescence excitation and emission at different wavelengths, allowing detection under various lighting conditions including ambient light. The dye's selective binding to hemoglobin or blood proteins produces a distinct spectral signature for accurate bloodstain identification.
Solution Approach 2:
The invention transitions from temporal measurement (short-lived luminescence) to spectral measurement (fluorescence emission at specific wavelengths). By using a dye with excitation and emission spectra that can be measured with standard forensic equipment, the test duration is extended and can be performed under normal lighting conditions, resolving the contradiction between detection accuracy and ambient light compatibility.
2Measurement precision
If luminol test is used for bloodstain detection, then blood can be detected, but DNA present in suspected bloodstains may be damaged
Solution Approach 1:
The patent introduces a fluorescent dye as an intermediary substance that selectively binds to blood components (hemoglobin or blood proteins) without requiring the harsh chemical conditions of luminol. This intermediary approach allows blood detection through fluorescence while avoiding the strong oxidizing agents and extreme pH conditions that damage DNA, thus preserving genetic material for subsequent analysis.
Solution Approach 2:
The invention replaces the chemical oxidation mechanism of luminol with a fluorescence-based detection mechanism. Instead of using strong oxidants that can damage biological molecules, the patent employs a dye that fluoresces upon binding to blood components, providing a gentler detection method that preserves DNA integrity while maintaining bloodstain detection capability.
3Ease of manufacture
If newer cleaning products with active oxygen are used, then cleaning effectiveness is improved, but they completely circumvent the luminol test by disfiguring hemoglobin
Solution Approach 1:
The patent changes the detection parameter from chemiluminescence (which relies on intact heme iron for catalysis) to fluorescence based on dye binding to blood proteins. This parameter change makes the detection method insensitive to cleaning products that modify heme structure, as the dye can still bind to other blood protein components that remain after cleaning, restoring test reliability.
4Measurement precision
If NIR-emitting dyes are used for blood detection, then increased resolution and emission output are achieved, but the dyes are less fluorescent in whole blood compared to pure albumin solution
Solution Approach 1:
The patent applies local quality enhancement by using ionic liquids that specifically interact with the dye-blood protein complex at the molecular level. The ionic liquid modifies the local microenvironment around the bound dye, enhancing its fluorescence quantum yield in the complex matrix of whole blood. This localized modification compensates for the quenching effects of the blood matrix while preserving the high resolution benefits of NIR detection.
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 offers a highly specific and durable blood detection method, with enhanced fluorescence in the presence of blood, allowing for accurate identification even after exposure to cleaning products and without damaging DNA, and can be used in various forensic applications.
Implementation Method 1
NIR-emitting dyes are garnering a lot of attention due to their uniquely high emission output in a spectral region with relatively few biological species absorbing light
Implementation Method 2
some undergo a sharp increase in fluorescence quantum yield (ΦF) upon an interaction with specific biomolecules
Implementation Method 3
Ionic liquids (ILs) are a class of compounds that are viscous salts at less than 100° C. or, in many cases, at room temperature
Data Source
AI summary
In one aspect, the disclosure relates to compositions comprising an ionic liquid and a near infrared (NIR) dye. In some aspects, the ionic liquid can be choline glycolate with the cation and anion present in a 1:1 ratio and the NIR dye can be SO3SQ. Also disclosed are methods of making the compositions and methods of using the compositions to positively identify substances as blood. In one aspect, the compositions are shelf-stable, do not damage DNA present in suspected bloodstains, and are highly specific for human blood.