Magnetically separable and recyclable bamboo-like carbon nanotube-based FRET assay for sensitive and selective detection of Hg

The global occurrence of toxic hazards in aquatic ecosystems has aroused concern about the potential impacts on the ecological environment and human health in recent decades. Mercury(II) ions that originate from widespread sources including the mining industry, fossil fuel consumption, and industrial wastes are now well known as a highly toxic pollutant. Despite various detection methods which have been reported to sense Hg2+, it still poses a great challenge for us to develop a new effective sensing platform to replenish current fluorescent detection techniques. Here, we report a novel fluorescent biosensor using bamboo-like magnetic carbon nanotubes (BMCNTs) and FAM-labeled T-rich ssDNA for efficient detection of Hg2+ in aqueous solution. The proposed biosensor shows a good response toward Hg2+ detection over a linear response range of 0.05~1 μM (R2 = 0.98) with a detection limit of 20 nM. It also exhibits the capability to discriminate Hg2+ ions with negligible response to other metal ions, such as Ca2+, Cd2+, Cu2+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+. Interestingly, the BMCNTs could be separated and recycled easily by using an external magnet, which means a much more cost-effective, easy-to-operate, and eco-friendly method for Hg2+ ion detection.