Copper is an essential trace metal in living organisms, but excessive copper intake can pose significant risks to plant, animal, and human health through the food chain. Developing a sensitive, non-destructive, and real-time technology to evaluate plant uptake of copper is essential, but it remains a challenging task at present. Single walled carbon nanotubes (DNA CNTs) wrapped in DNA have been widely used in biosensing and imaging technologies due to their fluorescence properties in the near-infrared (NIR) region, as well as their good water solubility and biocompatibility. Although significant progress has been made in the application of DNA CNTs in sensing, the widely used varieties are still unpurified carbon nanotubes with multiple chirality (Figure 1a). The complex composition and unclear DNA structure in unpurified sensors seriously hinder our understanding of sensing mechanisms. In response to these issues, based on previous work (Science 2022377, 535-539;  ACS Nano 2022,16,  4705-4713;  ACS Nano 2025,  19, 2665–2676； Sci. Adv. 2025, 11, eadt9844）， Recently, the research group led by Lin Zhiwei from the School of Advanced Soft Materials at South China University of Technology has developed an ultra sensitive and highly selective Cu2+sensing platform based on periodic ordered DNA wrapped single chiral CNTs (Figure 1b). This platform clarifies the sensing mechanism of DNA CNTs for Cu2+and achieves real-time and quantitative detection of Cu2+in living plants. The research findings were recently published in the internationally renowned journal ACS Nano. PhD student Chen Jianying is the first author of this article, and Professor Lin Zhiwei is the corresponding author.

The author used aqueous two-phase technology to separate five different chiral single chiral CNTs (DNA scCNTs). Based on previous research, the DNA decomposition sequences on these five purified scCNTs exhibited periodic ordered encapsulation structures (Sci. Adv. 2025, 11, eadt9844). By observing the fluorescence response of these five different DNA scCNT sensors to Cu2+, it was found that the fluorescence response of CNTs to Cu2+is highly dependent on chirality, and C3GC6GC4- (7,5) has the best sensing performance. In addition, non purified CNTs have weak optical response to Cu2+and it is difficult to quantify the sensitivity of each chirality due to their spectral overlap. By evaluating the performance of the (7,5) sensor in detecting Cu2+, the (7,5) sensor demonstrated excellent sensitivity, specificity, and stability.