3D-printed colorimetric copper ion detection kit and portable fluorescent sensing device using smartphone based on ratiometric fluorescent probes.

Copper ion (Cu) is not only a transition metal ion but also a significant environmental pollutant. The imbalance of Cu content will threaten the safety of the environment and even life. The portable detection devices based on ratiometric fluorescent probes have garnered increasing attention and acclaim because of their reliable analysis parameters. Therefore, two Cu ratiometric fluorescent probes (RH-1 and RH-2) were developed, which exhibit pronounced fluorescence changes, high sensitivity, excellent selectivity, and large Stokes shift. Both probes are capable of detecting Cu in water and milk samples. It is worth noting that a 3D-printed fluorescence sensing device was constructed using RH-1, and a new 3D-printed copper ion detection kit was developed based on RH-2, enabling on-the-spot estimation of Cu concentration. These devices significantly facilitate Cu detection in daily life. RH-2 has been successfully employed for imaging Cu in living cells and zebrafish. In conclusion, this work provides, for the first time, the 3D-printed ideal tools for detecting Cu. It also provides valuable insights for the establishment of on-site portable detection methods for other important substances.