"Technical Note:" Optimisation of Diamond™ Nucleic Acid Dye preparation, application, and visualisation, for latent...

Area of Science:

• Forensic Science
• Molecular Biology

Background:

• Latent DNA sampling is crucial but challenging in forensic investigations.
• Current methods often rely on subjective expert judgment.
• Diamond™ Nucleic Acid Dye (DD) offers a potential rapid screening tool.

Purpose of the Study:

• To evaluate Diamond™ Nucleic Acid Dye (DD) for latent DNA visualization on non-porous substrates.
• To optimize DD application methods for improved DNA fingerprint detail.
• To assess different visualization tools for latent DNA.

Main Methods:

• DD was applied to various non-porous substrates (polypropylene, acrylic, aluminum, PVC, glass, silicon).
• Methods involved micropipette application of DD in ethanol-water solutions.
• Spray application and altered ethanol-water ratios were tested to mitigate crystal formation.
• Visualization was performed using portable fluorescence microscopes (Dino-Lite, Zeiss Widefield).

Main Results:

• Micropipette application resulted in crystal formation, impairing DNA visualization.
• Spray application of DD eliminated crystal formation on all tested substrates.
• Changes in ethanol-water ratio did not significantly improve drying time or crystal mitigation.
• Zeiss Widefield microscope proved efficient for whole print imaging in a lab setting.

Conclusions:

• Spray application of Diamond™ Nucleic Acid Dye (DD) is superior to micropipette methods for latent DNA visualization on non-porous surfaces.
• Optimized DD application enhances DNA fingerprint detail by preventing crystal artifacts.
• The Zeiss Widefield microscope is a valuable tool for forensic latent DNA analysis.