A green method of staining DNA in polyacrylamide gel electrophoresis based on fluorescent copper nanoclusters synthesized in situ

The safety of nucleic acid staining dyes has long been recognized to be a problem. Extensive efforts have been made to search for alternatives to the most popular but toxic staining dye, ethidium bromide （EtBr）. However, so far no staining method that can be guaranteed to be suffidently safe has been developed. In this paper, we report a green staining method of DNA in polyacrylamide gel electrophoresis, where in situ synthesis of DNA-templated fluorescent copper nanoclusters （CuNCs） in the gel is achieved to make the DNA bands visible under UV light. Moreover, a comprehensive study of the performance of this staining method has been conducted and the experimental results show that it has favorable sensitivity, stability, and usability. Meanwhile, in our animal experiments, the two reagents （copper sulfate and ascorbic acid） as well as the synthesized CuNCs have been proven to be non-toxic in contact with skin. In addition, all the reagents employed in this work are readily available and low cost, and the procedure is simple to carry out. Therefore, this novel staining method based on the in situ synthesis DNA-templated fluorescent CuNCs has many potential applications.