Duration of in situ fluorescent signals within hairs follicles

Nuclei within anagen hair follicles can be viewed using fluorescent microscopy after staining with a nucleic acid binding dye. Anagen hairs are still in the growth phase and generally only removed by force such as pulling, plucking or trauma and can be important evidentiary items at a crime scene. Staining of the hairs can be a fast, easy, method to determine if hair samples have DNA present making it worthwhile to attempt to obtain a DNA profile for evidentiary purposes. SYBR^® Green I and Diamond™ Nucleic Acid Dye are two such dyes. The duration of the in situ fluorescent signal of both these nucleic acid dyes was studied to determine how long the samples can be kept in storage after staining yet still be capable of producing a fluorescent signal. Our results show that when stained with Diamond™ Nucleic Acid Dye the fluorescent signal could be viewed months after initial staining period. However when the hair was stained with SYBR^® Green I there was a significant reduction in the fluorescent signal within 7 days of initial staining. Our conclusion is that Diamond™ Nucleic acid dye was a viable dye for staining hair and keeping the samples in storage for later analysis.