Development of a modified p-dimethylaminocinnamaldehyde solution for touch DNA analysis and its application to STR...

Area of Science:

• Forensic Science
• Molecular Biology
• Analytical Chemistry

Background:

• Traditional methods for visualizing biological samples on textiles can be cumbersome.
• p-dimethylaminocinnamaldehyde (DMAC) is a reagent used for detecting biological traces.
• Optimizing DMAC application for forensic field use, particularly for touch DNA, is crucial.

Purpose of the Study:

• To develop and evaluate an acid-free DMAC spray formulation containing silicone oil for visualizing biological samples on clothing.
• To assess the impact of this DMAC solution and blue light-emitting diode (LED) irradiation on subsequent short tandem repeat (STR) DNA analysis.
• To determine the suitability of the method for touch DNA analysis in forensic investigations.

Main Methods:

• An acid-free DMAC solution with silicone oil was developed for spray application.
• Biological samples (saliva, sweat, touch DNA) were deposited on various surfaces (T-shirts, glass slides).
• Samples were treated with DMAC solution, exposed to blue LED light, and analyzed for DNA extraction, quantification, and STR profiling.

Main Results:

• The acid-free DMAC solution effectively visualized saliva, sweat, and fingerprints on T-shirts for up to 3 days under blue LED light.
• No significant differences in fluorescence intensity were observed between acid-added and acid-free DMAC solutions.
• The DMAC solution and blue LED irradiation did not adversely affect DNA extraction, quantification, or STR analysis.
• Addition of acid to DMAC showed minimal impact on DNA integrity and STR analysis outcomes.

Conclusions:

• The developed acid-free DMAC spray is a viable and effective tool for visualizing biological samples on clothing for forensic applications.
• The combination of DMAC solution and blue LED light is compatible with downstream STR analysis, including touch DNA.
• This method offers a promising, non-destructive approach for enhancing evidence detection in forensic investigations.