Azo-based food colours as cost-effective and safe tracking dyes for qualitative electrophoretic analysis of nucleic acids and proteins

Synthetic organic colours that contain the azo group (-N=N-) are a major component of dyes widely used in the textile and food processing industries. Given the ready availability of food colours, their modest cost and established safety profiles, we evaluated their suitability as tracking dyes for the gel electrophoresis of nucleic acids and proteins. We have tested 3 azo-based food colours, viz., Orange Red, Lemon Yellow and Bright Green, procured from local grocery stores for this purpose. The results are qualitatively comparable to those obtained using established methods of loading proteins and nucleic acids with the widely used dyes, bromophenol blue and xylene cyanol. This method entails no modification of current protocols for sample loading and gel electrophoresis. Use of these reagents that are 'commonly considered safe' and available at a fraction of the cost of equivalent analytical grade reagents would be advantageous in routine molecular biology procedures, especially in resource limited contexts.