A simple lateral flow biosensor for the rapid detection of copper(II) ions based on click chemistry

Copper(II) ions (Cu2+) at a high concentration are harmful to human health. Herein a simple and enzyme-free lateral flow biosensor for the rapid detection of Cu2+ based on copper(I) ion (Cu+)-catalyzed click chemistry has been constructed for the first time. In the presence of sodium ascorbate, Cu2+ was reduced to Cu+, which could catalyze the cycloaddition between azide-DNA and alkyne/biotin-DNA in aqueous solution. The ligated DNA product could then be immobilized onto the test zone of the lateral flow biosensor to form a red band which could be unambiguously read by the naked eye. Taking advantage of the optical properties of gold nanoparticles (AuNPs) and high efficiency and selectivity of Cu+-catalyzed click chemistry, this assay enabled the visual detection of Cu2+ as low as 100 nM with excellent specificity. In comparison with conventional methods, this biosensor is more simple to operate and more cost-effective to use, and therefore has great potential in point-of-care diagnosis and environmental monitoring.